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Residential Photovoltaic Systems


Alice Solar City

Final report


Published by the Alice Springs Town Council, lead proponent of the Alice Solar City Consortium

July 2013

Residential Photovoltaic Systems i

Table of Contents

1. Context .............................................................................................................................................................................. 1

1.1 Background and Aims ........................................................................................................................................................... 1

1.2 BP Solar as ASC Sole PV Provider .......................................................................................................................................... 1

1.3 ASC Target for PV System Installation .................................................................................................................................. 2

1.4 Financial Aspects of the BP Residential PV Systems ............................................................................................................. 2 1.4.1 Financial incentives for the purchase of BP-PV systems ............................................................................................... 3 1.4.2 Cost reflective and buyback tariffs for BP-PV systems .................................................................................................. 3

2. Design, Technical and Data Aspects for Rooftop BP-PV Systems ........................................................................................ 5

2.1 Technical Information ........................................................................................................................................................... 5 2.1.1 Roof mounting - performance requirements ................................................................................................................ 5 2.1.2 Roof mounting system and regulation .......................................................................................................................... 5 2.1.3 Inverter selection .......................................................................................................................................................... 6 2.1.4 Metering arrangement .................................................................................................................................................. 6 2.1.5 Meter reading and billing .............................................................................................................................................. 7

2.2 Explanations and Assumptions Associated with the BP-PV Data ......................................................................................... 7

2.3 Reporting Requirements ....................................................................................................................................................... 9

3. Residential PV Performance ............................................................................................................................................... 9

3.1 Number, Capacity and Costs of PV Systems Installed ........................................................................................................... 9

3.2 Tenures, Transitions and Idiosyncrasies for BP-PV Installations......................................................................................... 11

3.3 Generation of Kilowatt Hours per Kilowatt Installed .......................................................................................................... 12 3.3.1 Theoretical outputs ..................................................................................................................................................... 12 3.3.2 Actual and theoretical outputs using systems with available data ............................................................................. 13 3.3.3 Estimated outputs for all installed BP-PV systems (277) ............................................................................................. 15 3.3.4 Changes in annual electricity use in households with BP-PV ...................................................................................... 16 3.3.5 Household electricity generation compared to electricity consumption .................................................................... 17

3.4 Effects of Orientation and Other Variables ........................................................................................................................ 17 3.4.1 Actual performance compared to theoretical including shading ................................................................................ 18 3.4.2 Solar exposure, temperature and Monthly PV output ................................................................................................ 18

3.5 Total GHG Savings from Residential PV .............................................................................................................................. 20

3.6 Direct PV Costs per Output Units ........................................................................................................................................ 21

3.7 Performance of Inverter Upgrade....................................................................................................................................... 21

4. Residential PV buyback .................................................................................................................................................... 22

4.1 PV System Uptake and the Influence of the Elevated Buyback Tariff ................................................................................. 22 4.1.1 Relevant results from the BP-PV survey ...................................................................................................................... 23 4.1.2 Conclusions from the BP-PV survey ............................................................................................................................ 26

4.2 Success and Cost of PV Buyback Tariff ............................................................................................................................... 26

5. Learnings and Issues ........................................................................................................................................................ 27

Program Design ........................................................................................................................................................................ 27

5.1 Decision to Purchase PV ..................................................................................................................................................... 27

5.2 Installation of PV ................................................................................................................................................................ 27

5.3 Operation and Maintenance of PV ..................................................................................................................................... 28

Residential Photovoltaic Systems ii

6. Appendices ...................................................................................................................................................................... 29

Figures

Figure 1: BP-PV monthly installations and capacity ..................................................................................................................... 11 Figure 2: Solar exposure, temperature and monthly PV output .................................................................................................. 20

Tables

Table 1: ASC BP-PV, targets and actual installations ...................................................................................................................... 2 Table 2: BP-PV residential packages ............................................................................................................................................... 2 Table 3: BP-PV costs and incentives ............................................................................................................................................... 3 Table 4: PWC electricity tariffs during the ASC Program ................................................................................................................ 4 Table 5: Gross generation buyback tariffs for BP-PV ..................................................................................................................... 4 Table 6: Components of BP-PV systems ......................................................................................................................................... 5 Table 7: ASC PV reporting requirements ........................................................................................................................................ 9 Table 8: Summary of ASC BP-PV installations ................................................................................................................................ 9 Table 9: BP-PV monthly installations and capacity ...................................................................................................................... 10 Table 10: BP-PV owner-occupiers, landlords and new builds ...................................................................................................... 11 Table 11: BP-PV terminations ....................................................................................................................................................... 12 Table 12: BP-PV theoretical annual outputs ................................................................................................................................ 13 Table 13: BP-PV systems with two years of generation data ....................................................................................................... 13 Table 14: BP-PV monthly generation data – system type averages ............................................................................................. 14 Table 15: BP-PV total annual generation, 2011-12 ...................................................................................................................... 14 Table 16: BP-PV system type annual average outputs ................................................................................................................. 15 Table 17: BP-PV extrapolated output for all systems ................................................................................................................... 16 Table 18: BP-PV ADC before & after installation .......................................................................................................................... 16 Table 19: BP-PV monthly gross generation and gross consumption over two years ................................................................... 17 Table 20: BP-PV actual and closest theoretical outputs ............................................................................................................... 18 Table 21: Solar exposure, temperature and monthly PV output ................................................................................................. 19 Table 22: BP-PV greenhouse reductions ...................................................................................................................................... 21 Table 23: PV costs per unit kWh and GHG savings ....................................................................................................................... 21 Table 24: Analysis of performance of Energizer 2000 by inverter type (2012 data) .................................................................... 22 Table 25: Number of ASC BP-PV installations per period ............................................................................................................. 23 Table 26: Survey responses - understanding of the buyback tariff .............................................................................................. 24 Table 27: Survey responses -reasons for installation of BP-PV .................................................................................................... 24 Table 28: Survey Responses - Satisfaction with BP-PV ................................................................................................................. 25 Table 29: Survey responses - consideration of PV for new property ........................................................................................... 25 Table 30: Electricity bills in credit ................................................................................................................................................. 26 Table 31: Actual and potential cost to ASC of the elevated buyback tariff .................................................................................. 27

Residential Photovoltaic Systems iii

Acronyms

The following acronyms are used throughout the Alice Solar City reports:

Acronym Meaning Acronym Meaning

ABS Australian Bureau of Statistics KRR key results reporting

ADC average daily consumption kW kilowatt

AS Alice Springs kWh kilowatt hour

ASC Alice Solar City kWh/yr kilowatt hour per year

ASTC Alice Springs Town Council LBEA Large business energy audit

BMS building management system LBEEP large business energy efficiency

program

BP BP Solar LEDs light emitting diodes

CAT Centre for Appropriate Technology LGA Local Government

CEA commercial energy audit MER monitoring, evaluation and reporting

CEC Clean Energy Council MWh megawatt hour

CES commercial energy survey NB new build

CFL compact fluorescent lamp NT Northern Territory

CG Control Group OSB one shot booster switch

CO2 carbon dioxide OTP over temperature protection

CRT cost reflective trial PTR pressure and temperature Relief

DB database PV photovoltaic

DCCEE Department of Climate Change and

Energy Efficiency PWC Power and Water Corporation

Deg C degrees celsius REC Renewable Energy Certificate

EC electricity consumption RET Renewable Energy Target

EEM energy efficiency measure SBEEP small business energy efficiency

program

EEV energy efficiency voucher SD Sunny Design

FUS follow up survey SHW solar hot water

GHG green house gases SHWS solar hot water system

GIS geographic information system SLA statistical local area

GSM global system mobile communication SLC Smart Living Centre

HEA home energy audit SMA SMA Pty LTD

HES home energy survey SME small to medium enterprise

HVAC heating, ventilation and air conditioning SRES Small Renewable Energy Scheme

HW hot water STC Small Scale Technology Certificate

HWS hot water system V volt

ID's Identities VFD variable frequency drive

IGUs insulated glass units W watt

IHD in house display WELS water efficiency labelling and standards

KAB knowledge attitude and behaviour

Residential Photovoltaic Systems 1

Introduction

This document reports on the photovoltaic (PV) systems component of the residential element in the Alice Solar City

(ASC) program. It includes, and is structured around, the key reporting requirements for the Australian Government,

which was the major funder through the national Solar Cities program. It provides relevant contextual and technical

information, as well as documenting assumptions and rationales associated with information and data management. It

also incorporates other aspects of relevance and interest.

The primary audiences are the program sponsors, and although the report is quite detailed, it is not highly technical and

is suitable for interested readers.

1. Context

1.1 Background and Aims

At the commencement of the ASC project in March 2008, only two existing rooftop grid-connected PV systems were

identified on homes in Alice Springs, despite both the climatic suitability and the uptake of such systems elsewhere in

Australia1. This apparent anomaly can be largely explained by two factors:

1 The Alice Springs Solar City expression of interest bid was shortlisted in December 2005 and the success of the final

bid was announced in April 2007. Residents contemplating PV installation during this period and up to the official

ASC launch were likely to await the availability of an incentivised option through the ASC project, and so not initiate

PV installation.

2 Until the ASC program commenced, the promotion and installation of residential grid-connect PV systems was not

part of the service offered by electrical contracting businesses in Alice Springs.

The ASC incentivised PV systems were only available in the Alice Springs greater municipality, and to households that

were connected to the local electricity grid and had registered as an ASC customer.

The aims of the ASC Residential PV component were to:

increase the uptake of household PV

increase household and community awareness of the PV technology, and to demonstrate that PV is a viable

option for households in Alice Springs

reduce demands on the local electricity generation system, a service provided by the sole local utility, the NT

Power and Water Corporation (PWC)

reduce greenhouse emissions due to household electricity consumption

trial the influence of a cost reflective tariff linked with the installation of residential PV.

1.2 BP Solar as ASC Sole PV Provider

During the initial ASC program planning (2007/2008), ASC established a funded sole-provider agreement with BP Pty Ltd

(BP) at an agreed unit price, (subject to limited variations based on changes in market conditions). For residential ASC

customers who applied to install a grid-connected PV system as an ASC incentivised measure, BP undertook to:

conduct residential site assessments for PV suitability

provide quotations for the installation of specified PV systems

employ an accredited PV system installer.

1 5493 PV systems had been installed throughout Australia between 2001-2007, http://cleanenergyaustraliareport.com.au/2011-

technologies/photovoltaic-solar-panels

http://cleanenergyaustraliareport.com.au/2011-technologies/photovoltaic-solar-panels

http://cleanenergyaustraliareport.com.au/2011-technologies/photovoltaic-solar-panels


If the quotation was accepted by the residential customer, and approved by ASC, BP undertook to:

complete the requisite application and compliance forms for PWC

install the PV system, complete the grid connection, and provide an in-house display (IHD)

notify PWC to replace the existing electricity meter with a smart meter that records gross consumption and gross

generation at 30 minute intervals, can be read remotely via a phone modem, and that can communicate locally

with the IHD

provide suitable manuals for customer use

provide a warranty of 25 years for the PV modules and 10 years for the inverter

undertake a 12 month system maintenance check.

BP engaged a qualified and experienced installer to provide quotes, do the installations and the first year system check,

and to undertake any warranty work.

1.3 ASC Target for PV System Installation

The project targets (initial and revised) for the installation of ASC subsidised BP-PV systems are shown in the table below

together with the actual number of project installations:

Targets Actual

Initial - March 2008

(from Business

Case)

Revised - May

2009 Achieved

Total nominal kWp 250 300 535

Number of 1 kW systems 175

Not specified

14

Number of 1.5 kW systems 50 9

Number of 2 kW systems 254

Table 1: ASC BP-PV, targets and actual installations

In terms of customer commitment through signed purchase agreements based on installer quotations, the revised target

(of May 2009) was reached and exceeded in December 2009 by approximately 80%, (target of 300 kWp, actual of 535

kWp). The ASC financial situation in 2009 enabled an increase in the original BP-PV budget to support the possibility of

demand exceeding the target of 300 kWp, and a decision was made to direct additional funds to support PV.

Installations were completed by June 2010. The 2kW systems were by far the most popular and, for most customers, the

most economic. Compared to a 1.5kW system, the increased cost of a 2kW system was more than offset by the increase

in the value of solar credits then available.

1.4 Financial Aspects of the BP Residential PV Systems

BP offered three residential PV packages of the ‘Energiser’ model:

Name Rating Panels Inverter Nominal estimated annual

electricity generation

Energizer 1000 990W 6 x 165W SB 1100 1600 kWh

Energizer 1500 1550W 10 x 155W* SB 1700 2500 kWh

Energizer 2000 1980W 12 x 165W SB 1700 3200 kWh

*This package changed to 10 x 165W later in the ASC project

Table 2: BP-PV residential packages


The packages included an IHD and smart meter that replaced the existing accumulation meter and recorded gross

consumption and gross generation at 30 minute intervals.

1.4.1 Financial incentives for the purchase of BP-PV systems

Customers paid somewhat less than half of the total cost of an installed system. The subsidies were:

1 a direct cash subsidy from the ASC project

2 a BP environmental cashback –‘envirocashback’- based on the value of the sale of certificates under the Australian

Government’s national Renewable Energy Target (RET) scheme.

Initially the BP envirocashback represented the purchase of Renewable Energy Certificates (RECs) at a fixed rate. After

changes were made to the RET it represented purchase of Small-scale Technology Certificates (STCs) under the Small-

scale Renewable Energy Scheme(SRES) including the new Solar Credits multiplier. ASC was required to reduce its capital

incentive by the value of the Solar Credits multiplier so that the net cost to customers for the system packages remained

the same after introduction of the SRES. Due to uncertainty over both the legislation and likely market price for STCs,

and the consequent impact on the BP PV system quotations, the ASC subsidy and the envirocashback were generally

combined into a single figure that represented the actual cost to the customer if the RECs/STCs were assigned to BP.

Customer acceptance of a quote that included the BP envirocashback meant that BP received the RECs/STCs for the PV

installation. Customers could however choose not to receive the BP environmental cashback, thereby assuming

ownership of the RECs/STCs and increasing the net upfront cost of the system.

In addition to these upfront rebates, customers were also entitled to an elevated buy-back tariff for electricity generated

by their PV systems (see 1.4.2).

Through worldwide reductions in the cost of PV equipment, the standard fixed package price (GST inclusive) provided by

BP decreased after June 2009 (see table below). Thus ASC customers installing PV systems after June 2009 paid around

20% less than those who installed before that month. The table below shows these differences in cost, but does not

include the value of the BP envirocashback.

Before June 2009 After June 2009 Reduction

in total cost Name Total cost ASC

incentive Total cost

ASC

incentive

Energizer 1000 $14,900.00 $7,920.00 $13,981.99 $7,920.00 $918.01

Energizer 1500 $20,208.00 $10,104.00 $18,394.68 $9,197.34 $1,813.32

Energizer 2000 $25,042.00 $12,521.00 $21,157.95 $10,578.97 $3,884.05

Table 3: BP-PV costs and incentives

The dollar amounts for individual residential systems recorded in the ASC database are the total system cost and the

ASC incentive. The value of the BP envirocashback was not recorded, in part because some customers elected to forego

this incentive, and also for consistency with some other residential energy-efficiency incentives, for which additional

rebates may have applied but were not recorded in the database voucher information (e.g. Solar Hot Water (SHW)

installations).

1.4.2 Cost reflective and buyback tariffs for BP-PV systems

The tariff arrangements until June 2013 for customers who installed an ASC-incentivised BP-PV system were:

1 Electricity consumption – as a condition of receiving ASC financial support to purchase a BP-PV system, customers

moved onto the cost reflective tariff (CRT). The CRT was created as part of the ASC program and based on the 30

minute gross consumption data as recorded by the Smart Meter - with peak and off-peak periods and tariffs defined

as follows:

Peak: 9am – 6pm weekdays;

Off-peak: all other times (i.e. 6pm – 9am weekdays, and all weekends).


Tariff

Cents per kWh

FY*

2008-

09

FY

2009-10

FY

2010-11

FY

2011-12

July 1 -Dec 31

2012

Jan 1 – June

30 2013

Standard (flat) rate 15.52 18.31 19.23 19.77 21.77 25.83

Peak rate 23.11 27.27 28.63 29.43 31.07 37.75

Off-peak rate 13.01 15.35 16.12 16.57 18.48 21.89

*FY: financial year

Table 4: PWC electricity tariffs during the ASC Program

A new NT Government was elected in August 2012 and increased electricity tariffs significantly from January 1 2013. The

implications of these tariff increases are not included herein as the relevant PV data collection for this report was

concluded on December 31 2012.

2 Electricity generation – the Smart Meters recorded gross PV generation, and an elevated PV gross generation

buyback tariff was provided to all the original BP-PV customers until the completion of the program. It had two

components:

the current PWC peak rate for electricity consumption, which increased in-line with PWC electricity price trends

(see below);

an ‘elevated buyback’ subsidy provided from ASC funds and fixed at 22.65 cents/kWh generated.

By the end of the program the buyback tariff was worth 60.4 cents per kWh for ASC BP-PV customers.

Table 5: Gross generation buyback tariffs for BP-PV

Purchasers of properties with an ASC BP-PV system already installed (i.e. second owners of the BP-PV), were not eligible

for the elevated buyback tariff, and did not have to adopt the CRT. The generation tariff for second owners was at the flat

rate consumption tariff, and if such owners wished to move onto the CRT they had to sign up as an ASC customer and

choose to maintain the CRT for their new property.

Buyback Tariff

Component

Gross generation buyback tariff - cents per kWh generated by BP-PV systems

FY 2008-09 FY 2009-10 FY 2010-11 FY 2011-12 July-Dec 2012 Jan-June 2013

PWC (CRT peak

rate) 23.11 27.27 28.63 29.43 31.07 37.75

ASC 22.65 22.65 22.65 22.65 22.65 22.65

Total buyback 45.76 49.92 51.28 52.08 53.72 60.40


2. Design, Technical and Data Aspects for Rooftop BP-PV

Systems

2.1 Technical Information

The three BP residential PV packages were designed by BP engineers, and consisted of the following components:

System Inverter PV module

type

Module

capacity

(W)

Number

of

modules

Capacity

(watts)

Roof

requirements

Energiser

1000 SB1100

BP3165/

BP 4165 165 6 990 7.8m2 / 150kg

Energiser

1500 SB1700

BP3155 /

BP3165 155 /165 10 1550 /1650 13.0m2 /250kg

Energiser

2000

SB1700

/

SB2500

BP3165 /

BP4165 165 12 1980 15.6m2 /300kg

Table 6: Components of BP-PV systems

In all cases the SMA inverters came with an extended warranty of 10 years, and the BP modules came with a 25 year

output warranty, guaranteeing 80% of name plate capacity at 25 years.

BP supplied their own aluminium rail mounting system in a 3 and 4 module kit for direct mounting onto custom orb

corrugated iron roofs, certified to the relevant wind load standards. The preponderance of flat roofs in Alice Springs was

not taken into account initially by BP and there was no existing array tilt kit available. A custom solution was decided

upon, using a galvanised Z purlin in place of one of the rails to provide a 10 degree tilt where necessary.

2.1.1 Roof mounting - performance requirements

The optimal installation of a fixed PV array for Alice Springs was determined as facing due north, with a tilt from

horizontal at or close to 23 degrees. No specific requirements on tilt and orientation were set by ASC. ASC required all

quotes for a BP installation to include a site assessment including tilt, orientation, and a Sun Eye or equivalent

measurement of shading, with a requirement for the loss estimate to be less than 20% to be eligible for funding.

2.1.2 Roof mounting system and regulation

Building regulation in the Northern Territory is encompassed by the NT Building Act and associated Regulations, and

administered by the Building Advisory Services Branch, utilising a Building Advisory Committee. The Act is aligned to the

Building Code of Australia. The solar PV industry in the Northern Territory operated with an assumed exemption from the

requirement to obtain a building permit for roof mounted solar PV up until late 2010, when advice was obtained that

there was no exemption and a full building permit was required.

ASC led the industry in seeking to establish an exemption from this requirement. As a result of this lobbying, on the

8/4/2011 the Building Advisory Committee adopted a policy for the installation of PV panels for non cyclonic regions to

facilitate the installation of PV panels on roofs without the requirement to obtain a building permit (Policy No

BAC2011/001). This policy applies to Class 1 and Class 10 structures in non-cyclonic regions of the Northern Territory

(Regions A and B as per AS/NZS1170.2).

The installation of PV panels in non-cyclonic areas is exempt from the requirement to obtain a building permit provided

that:

the installer is accredited with the Clean Energy Council of Australia (CEC)

the panels installed are approved by the CEC, and either


a) The roof is structurally sound, as certified by a structural engineer, building certifier or building contractor

registered with the NT Building Practitioners Board or

b) A building permit was issued for the building in question within five years of the proposed installation.

On completion of the installation, the accredited installer must issue a written declaration that all these conditions have

been met and provide full documentation to the property owner. The property owner is responsible for keeping the

documentation for future reference. PV panels shall not be installed in the local pressure exclusion zones for Region B,

unless otherwise determined by an engineer.

Certification of PV mounting structure for wind loading in accordance with AS/NZS 1170.2 is required by the CEC Grid

Connect Installation guideline in the form of an array frame engineering certificate and array frame installation

declaration. Under verification of AS/NZS1170.2 installers are required to "obtain from their frame supplier a copy of the

engineering certificate stating that the array frame is certified to AS/NZS 1170.2 for their location. They must also obtain

information on how the frame is to be mounted on the roof to maintain this certification."

2.1.3 Inverter selection

At the time of the design of the BP Energiser packages, careful research and modelling by BP and SMA Pty Ltd (SMA)

confirmed that the SB1700 inverter was the appropriate choice for use with the nominal 2kW system, despite its

maximum output being limited to 1.7kW peak (i.e. the peak/maximum output is 1.7kW). There was some concern

expressed by local installers, and subsequently by early customers, about the choice of inverter being inappropriate, in

part driven by the SMA supplied Sunny Design software showing a warning about the inverter selection. Written advice

was obtained from BP and SMA that the combination of 1980W of modules and the SB1700 inverter was appropriate for

Alice Springs conditions.

The next largest available inverter was the SMA SB 2500, which had a maximum AC power rating of 2500W. At the time,

the considerable price differential between the SMA SB1700 and SB2500 inverters, combined with the cost and

difficulty of accessing the higher voltage DC isolators required for the SB2500’s string arrangement meant that the price

difference was over $1500. Over a fifteen year life, at an estimated long term feed-in tariff of 25c, the upgraded inverter

would need to generate 400kWh more per year than the SB 1700 in order to break even, which equates to a 12.5%

increase in output. Modelling of the system performance with the larger inverter estimated a 3 to 4% increase in output,

which did not justify support of the upgrade.

2.1.4 Metering arrangement

In order to meet the Solar Cities program data requirements, the BP systems were installed with gross metering, whereby

each customer’s full consumption was metered separately from the PV system’s gross generation. This required the AC

output of the inverter to be connected directly to the meter box.

For single phase supply, a dual element EDMI MK7A meter was installed with a GPRS modem for remote

communications by PWC staff over the cellular mobile phone network, and a Zigbee Pro Modem for wireless

communication with the In-House-Display (IHD) via the zigbee protocol. For three phase supply, an EDMI Mk10D meter

was used, with a satellite meter connected to the output of the solar PV inverter providing a pulse input to the Mk10D

meter for the recording of PV generation.

For many customers on large blocks in the rural suburbs of Alice Springs, the existing metering location was at the

boundary of the property but the desired location of the solar power system was on a dwelling or other structure at some

distance from the boundary. In order to meet the requirement for gross metering while avoiding the need to install a

direct AC connection from the inverter back to the boundary metering location, these properties instead had a new

additional meter box installed on the building hosting the solar PV system. This arrangement was also of benefit in

regards to the IHD which requires a relatively short distance (generally up to 50 meters) for its wireless communication

with the smart meter.

For a few customers whose internal wiring made this impractical, the alternative of a ground mount array at the boundary

was used. In this situation, the smart meter went into the existing meter box with the result that the IHD was unlikely to

communicate from the dwelling to the more distant boundary metering location. Signal boosters were available for these

situations, to enable the wireless signal to reach the residence.

Refer to Appendix 1 for examples of the wiring arrangements.


2.1.5 Meter reading and billing

At the launch of ASC, PWC already had systems in place to remotely read interval meters for their larger commercial

customers. Their pre-existing system involves downloading 15 minute interval data into a dedicated interval data system

at the end of each month. This data is then transferred to the PWC retail billing section where it is summarised for billing,

allowing for dynamic calculation of separate peak and off-peak period consumption amounts and avoiding the need for a

manual meter reading to be taken on site.

This method was adopted for the ASC trials, with adjustments made to handle 30 minute intervals instead of 15 minute.

This choice had a number of consequences for billing:

The change to remote reading meant that the customer’s electricity reading was taken on a different day to that

for the water meter, resulting in the electricity and water/sewerage accounts being separated and invoices

issued separately for each. With a number of customers finding their electricity accounts in credit, arrangements

had to be made for this credit to be periodically transferred to the water account for the same property.

A cumulative meter reading was not obtained for billing, which relied instead on the summation of interval data

for the period, with the result that the customer’s electricity account meter reading was equal to the

consumption amount for that period.

Reliance on the automated transfer of data from the interval data system into the billing system made dealing

with problems and applying corrections more complex.

PWC encountered a number of supply and programming issues during the rapid rollout of the 277 smart meters required

for this trial (as well as for the additional 600 meters required for the CRT trial and its control group). An initial result was

that a number of BP installations were allowed to be temporarily connected in a net metering arrangement with the

existing accumulation electricity meters. When the smart meter was installed, a reading was taken from the PV inverter,

and this was used to calculate a reimbursement for customers of the elevated buyback that was lost in the wait for full

metering. ASC then also applied this figure to correct the meter readings for the net metering period, so that ASC records

represented the customer’s gross electricity consumption rather than net.

Additional problems resulted in both difficulty establishing remote connection to the meters for obtaining interval data,

and the meters periodically resetting and losing stored data. As a result a large number of the meters lost data for a

period before remote reading could be successfully established and the issue resolved. This represents a gap both in

records of power generation by the solar PV installations as well as in the customer’s gross consumption.

A number of estimates and other manual invoicing processes were therefore required for this period, causing additional

complexity in the billing records and a significant workload for PWC staff in converting the customers back to manual

billing temporarily to allow corrections to be made. This also had consequences for ASC handling and cleansing of billing

data that was received for customers.

2.2 Explanations and Assumptions Associated with the BP-PV Data

1 The three systems as supplied by BP were rated at 0.99, 1.55 and 1.98 kW.

2 Clean Energy Regulator sets deemed generation amounts for installations around Australia as part of the Renewable

Energy Target legislation. The conversion multiplier for the Australian geographic area classified by Clean Energy

Regulator as zone 1 (highest annual levels of solar radiation), of 1622 (x rated kW) was used to calculate a theoretical

estimate of kWh/yr generated by the three operational systems: i.e. 1606, 2514, 3211 kWh/yr respectively. The Clean

Energy Regulator multiplier is applicable to zone 1, which includes postcode areas of Australia in WA, NT, SA, and Qld that

are largely in the arid zone. The multiplier is calculated using a figure for daily solar radiation kWh/m2, (applicable across

zone 1) and de-rating factors (which are system losses that must derive to an ‘average’ that is applicable across the

range of systems available, and a range of possible tilts/orientations).

3 As part of the site assessment for the preparation of a quotation (and hence prior to installation), measures of panel tilt

and orientation were recorded, and, together with Alice Springs location parameters and system technical specifications

(make, model etc of panels, inverter, cabling), were entered into the Sunny Design software package to give a theoretical

estimate of annual output (kWh/year) for each individual residential system installed. This was a second theoretical


estimate, using finer parameters than the Clean Energy Regulator estimates, and as such can be expected to be more

accurate.

4 The orientation, tilt and shading losses were provided as part of the site assessment (prior to installation) and were

recorded in the ASC database; they were not measured after installation. Thus if any actual physical installation differed

significantly from the original site assessment and plan, the orientation tilt and shading parameters may have varied from

those at assessment and in ASC records.

5 The expected percentage loss per installation due to shading was provided by the installer as part of the site/roof

assessment using the Suneye modelling system. If installation of the PV panel layout was different to that proposed at

site assessment, a revised shading loss assessment was not conducted.

6 The expected shading loss estimates were used to adjust individual system theoretical annual outputs, for both Clean

Energy Regulator and Sunny Design theoretical outputs; e.g. 6% shading loss for a 2kW system gives 3211 x 0.94 =

3018 kWh/yr output (Clean Energy Regulator based).

7 The total installed capacity and theoretical outputs (the latter being both optimum theoretical estimates and those with

shading losses applies), were calculated by summing individual system capacities/outputs.

8 The costs are those recorded in the ASC database and financial system.

9 Costs used in analyses are:

the total cost of system(s) and

The subsidy provided by ASC, which does not include the value of RECs/STCs (a federal government subsidy

provided indirectly to the consumer via the BP envirocashback). The total subsidy varied slightly over the course of

the installations due to changes in system costs and the value of the envirocashback. Total project costs are

aggregated from individual installations (2 of which were free to ASC – one as a gift from BP to the sustainable living

house). The actual cost to the customer (the total cost less ASC subsidy less value of the envirocashback) was not

recorded directly by ASC.

10 Two CO2 conversion factors were used; they are taken from the National Greenhouse Accounts Factors published by the

Australian Government, are suitable for use over the 5 years of the program and are specific to the Northern Territory.

The Scope 1, or direct emission factor for the burning of fossil fuel to produce electricity, is 0.68kg of CO2 (or equivalent)

released per kWh electricity consumed. Adding Scope 3 emissions (those for transport of the fuel to the generation

facility and losses in the transmission of electricity from the place of its generation to end users), for which the NT figure

is 0.11, results in a total of 0.79kg of CO2 released per kWh electricity consumed. Including Scope 3 emissions was not

standard practice for the majority of ASC reporting, but is appropriate in the context of distributed generation. The

conversions factors of 0.68 and 0.79 are also used for PV generation to calculate the savings in greenhouse gas (GHG)

emissions saved by effectively replacing power-station generated electricity with solar generated electricity, which has no

direct GHG emissions. Please refer to the Residential Overview report for further details about the conversions factors

decided upon from the National Greenhouse Accounts.

11 No attempt has been made to integrate data/calculations over the 2 years of the installations - all calculations are

nominal for the relevant time periods (e.g. six months) in data tables.

12 The Clean Energy Regulator deeming period for PV RECs is 15 yrs; i.e. Clean Energy Regulator calculates the value of

RECs/STCs for 15 years of PV system output. The BP system panels have an 80% output warranty over 25 years.

13 Dollar costs per units of measure (kWh/yr generated and kgCO2/yr saved) have been calculated over a 15 year period

from the time of the completion of the installation of all systems, ignoring performance losses over time as well as

potential maintenance and other operational costs. The deeming period for which RECs/STCs are calculated is 15 years.

14 The performance losses over time (0.5% per year based on the performance guarantee of 80% after 25 years for the BP

modules), have likewise been excluded in the long term amortised costs per output.


2.3 Reporting Requirements

The general reporting structure is shown below.

ASC-DCCEE Key Results reporting: Residential PV

3. PV performance

3.1 Number, capacity and costs of residential PV systems installed

3.2 kWhs generated per kW installed

3.3 Effects of orientation and other variables (e.g. weather)

3.4 Total GHG savings from residential PV

4. Residential PV

buyback

3.1 The impact of the elevated buyback rate for rooftop PV systems in

the first two years of the ASC project (2008 –2010) in terms of

influencing the investment decision by the customer to install PV 3.2 Success of PV buyback – understanding by customers,

integration/administration issues

Table 7: ASC PV reporting requirements

3. Residential PV Performance

3.1 Number, Capacity and Costs of PV Systems Installed

At the end of June 2010, ASC had provided financial incentives for, and facilitated the installation of 277 residential BP-

PV systems.

Parameter Mar-June

08

Jul-Dec

08

Jan-Jun

09 Jul-Dec 09

Jan-Jun

10 Totals

BP Energiser 1000 PV system -

count 4 5 5 14


count 1 5 1 2 9


count 2 23 25 78 126 254

Total number of systems

installed 2 24 34 84 133 277

Total capacity kW 3.96 47.09 61.21 160.94 257.53 530.73

Clean Energy Regulator

theoretical annual output (kWh) 6423.1 76380.0 99282.6 261044.7 417713.7 860844.1

Clean Energy Regulator

Theoretical annual (CO2)

reduction (Kg)

4367.7 51938.4 67512.2 177510.4 284045.3 585374.0

Cost of systems installed $ 50,084 615,182 766,617 1,761,186 2,815,898 6,008,967

ASC incentive amount $ 25,042 298,087 382,063 670,886 957,987 2,334,065

Other cost: Customer and

cashback $ 25,042 317,095 384,554 1,090,300 1,857,911 3,674,902

Table 8: Summary of ASC BP-PV installations


By far the most popular system was the Energiser 2000 (1.98 kW), of which 254 were installed; there were 14

installations of the Energiser 1000 (0.99 kW) system and 9 of the Energiser 1500 (1.55 kW). The total capacity of all

systems installed was 531 kW, and the total cost was a little over $6,000,000. ASC contributed a direct incentive

amount of $2,334,000 (38.9%), which does not include the ASC portion of the elevated buyback tariff.

The rate of installations by month is shown in the table below. The latter part of 2009 and the early part of 2010 were

the busiest periods, reflecting the relatively slow take-up by Alice Springs residents of the ASC incentivised BP-PV

opportunity during the first 15 months of the program.

Year Month Number of

installations

Cumulative

installations

Capacity

kW

Cumulative

capacity

2008 May 2 2 3.96 3.96

2008 Aug 2 4 3.96 7.92

2008 Sep 4 8 7.92 15.84

2008 Oct 8 16 15.41 31.25

2008 Nov 5 21 9.9 41.15

2008 Dec 5 26 9.9 51.05

2009 Jan 5 31 8.48 59.53

2009 Feb 5 36 8.48 68.01

2009 Mar 8 44 15.41 83.42

2009 Apr 9 53 15.97 99.39

2009 May 1 54 1.98 101.37

2009 Jun 6 60 10.89 112.26

2009 Jul 12 72 22.77 135.03

2009 Aug 10 82 19.8 154.83

2009 Sep 20 102 36.2 191.03

2009 Oct 12 114 22.77 213.8

2009 Nov 17 131 33.66 247.46

2009 Dec 14 145 27.72 275.18

2010 Jan 22 167 43.13 318.31

2010 Feb 37 204 73.26 391.57

2010 Mar 48 252 89.66 481.23

2010 Apr 13 265 25.74 506.97

2010 May 7 272 13.86 520.83

2010 Jun 5 277 9.9 530.73

Table 9: BP-PV monthly installations and capacity


The BP-PV installation rate is shown graphically below.

Figure 1: BP-PV monthly installations and capacity

3.2 Tenures, Transitions and Idiosyncrasies for BP-PV Installations

The distribution of BP-PV installations on existing premises and newly built homes in relation to the tenure of the

occupants is shown in the table below.

Numbers of ASC BP-PV Installations

Tenure Total On Existing Premises New Builds

Owner-occupier 271 264 7

Landlord ( with

tenant) 6 6 0

Total 277 270 7

Table 10: BP-PV owner-occupiers, landlords and new builds

At tenanted residences where the landlord installed a BP-PV system, the standard 30 minute gross consumption and

gross generation data was collected for the holder of the electricity account, normally the tenant. Prior to the time of PV

installation, the tenant was required to register with the ASC program, and after installation move onto the CRT in order

to receive the elevated buyback for PV generation. Subsequent tenants were eligible only for the standard buyback rate,

i.e. the flat rate consumption tariff.

Residential population turnover in Alice Springs is significant, estimated at 50% every 5 years. Hence changes in

ownership and tenancy of residential properties were common during the 5 year life of ASC. When an ASC registered

property was sold or a tenanted property vacated, the new owner/tenant may or may not have signed-up with ASC as a

new customer/registration. For properties on which BP-PV was installed, the turnover shown in ASC records as of

December 2012 is given in the table below.


Table 11: BP-PV terminations

After signing a new Power Purchase Agreement with PWC, purchasers of residences that had an existing ASC BP-PV

system received the flat rate consumption tariff for their gross PV generation. If they joined ASC they could choose to

remain on CRT, but were not eligible for the PV elevated buyback. After changes in occupancy, PWC continued to collect

PV generation data via remote access, unless precluded by changes to customer conditions.

The ASC BP-PV group of customers was a self-selected group from the Alice Springs population, who were motivated and

financially able to take up the ASC PV offer and were effectively ‘early-adopters’ of the technology in Alice Springs. They

were not a group selected on a set of uniform parameters that would enable them to be classified as a scientific or

quasi-scientific experimental group. Thus the BP-PV households exhibited a range of ongoing daily life situations that in a

few cases compromised the quality or suitability of the PV generation data available to ASC. Some examples were: a

property from which panels were transferred to a new residence that was wired for type 2 metering (net

consumption/generation); a new build that was connected to the grid a long time after the PV panels were installed, and

soon after was sold; a residence at which the system was installed with half the array facing east and the other half

facing west; and a property at which the PV panels were removed for a year while house renovations were undertaken.

3.3 Generation of Kilowatt Hours per Kilowatt Installed

The calculations for this section have been done using both theoretical and actual PV outputs summed by individual

system in two ways:

1 across all systems, and

2 by those systems for which valid PV generation data was available over a two-year period.

Optimum theoretical annual generation in kWh/year was calculated by two methods:

1 using the Clean Energy Regulator conversion multiplier of 1622 kWh/annum generated per kW installed for Zone 1,

and

2 using the Sunny Design software, in which a calculation was done for each system based on a range of parameters

(panel tilt and orientation, Alice Springs location and meteorology, and PV panel and inverter specifications). The

Sunny Design theoretical estimate is based on more specific individual system data than the Clean Energy

Regulator multiplier, so would be expected to provide a more accurate overall estimate than the Clean Energy

Regulator multiplier. Shading losses were variable and specific to individual installations, so were not included in

either the basic Sunny Design or Clean Energy Regulator estimates. However, an estimated shading loss (as an

average percentage of the panel shaded during a year) was calculated at installation for each system and was

applied to both the Clean Energy Regulator and Sunny Design theoretical outputs.

Potentially, a full year’s PV generation data for all systems only became available from July 2010 when all systems were

installed. The actual PV generation per system by month until December 2012 was compiled and analysed from the

available 30-minute interval data. This analysis provided valid monthly generation data for 262 systems for the 24-

month period from January 2011 to December 2012. Thus actual output calculations are based on the data from these

262 systems.

3.3.1 Theoretical outputs

Clean Energy Regulator and Sunny Design theoretical optimum annual generations with and without estimated shading

losses are shown for all systems (277), summed by individual systems, in the table below. The total cumulative capacity

Numbers of ASC BP-PV registrations/terminations

Tenure Total Not terminated (Dec 2012) Terminated

(Dec 2012)

New occupant signed

with ASC

Owner- occupier 271 228 43 8

Tenant (-landlord) 6 3 3 0

Total 277 241 46 8


of all units has been rounded up to 531kW (from 530.73). Average estimated shading losses were 5.7%, based on the

estimated shading losses for each individual system.

Theoretical annual output for 277 installed systems - 531kW capacity

Estimate type kWh/year kWh/kW/year

Clean Energy Regulator annual estimate 860,844 1,622

Clean Energy Regulator annual estimate with

shading 811,684 1,529

Sunny Design annual estimate 908,224 1,710

Sunny Design annual estimate with shading 856,519 1,613

Table 12: BP-PV theoretical annual outputs

3.3.2 Actual and theoretical outputs using systems with available data

Actual 30 minute interval data (kWh export) for the 2011-2012 calendar years was available, complete and considered

accurate for 262 of the 277 installed BP-PV systems. The number and type of systems providing this data, compared to

installations, is shown below.

Parameter Energiser

1000

Energiser

1500

Energiser

2000 Overall

System capacity (kW) 0.99 1.55 1.98

Number of units installed 14 9 254 277

Capacity of systems installed (kW) 13.9 14.0 502.9 530.7

Number of units with valid data 14 8 240 262

Capacity of systems with valid data (kW) 13.9 12.4 475.2 501.5

Table 13: BP-PV systems with two years of generation data

Two years of valid data were available from all 14 of the Energiser 1000 systems, 8 of the 9 Energiser 1500 systems,

and 240 of the 254 Energiser 2000 systems, with an overall capacity of 501.5 kW compared to the installed capacity of

530.7 kW. This data is shown in the table below.

Average Monthly Total Output per

System kWh

Average Daily Output per Month per

System kWh

Year Month Energiser

1000 (14)

Energiser

1500 (8)

Energiser

2000 (240)

Energiser

1000 (14)

Energiser

1500 (8)

Energiser

2000 (240)

2011 Jan 151.41 235.10 314.43 4.9 7.6 10.1

2011 Feb 118.85 198.11 250.60 4.2 7.1 8.9

2011 Mar 110.48 186.70 236.59 3.6 6.0 7.6

2011 Apr 131.88 219.73 281.42 4.4 7.3 9.4

2011 May 102.43 167.75 221.05 3.3 5.4 7.1

2011 Jun 93.32 148.22 203.19 3.1 4.9 6.8

2011 Jul 93.73 150.77 204.54 3.0 4.9 6.6

2011 Aug 124.72 205.44 271.13 4.0 6.6 8.7

2011 Sep 120.75 205.68 262.36 4.0 6.9 8.7


2011 Oct 126.69 211.56 268.98 4.1 6.8 8.7

2011 Nov 128.51 208.38 267.64 4.3 6.9 8.9

2011 Dec 142.31 228.43 296.89 4.6 7.4 9.6

2011 Avge 120.42 197.15 256.57 4.0 6.5 8.4

2012 Jan 142.31 228.67 297.97 4.6 7.4 9.6

2012 Feb 138.65 227.20 296.53 4.8 7.8 10.2

2012 Mar 129.02 220.94 280.70 4.2 7.1 9.1

2012 Apr 111.73 189.09 242.52 3.7 6.3 8.1

2012 May 116.71 195.04 255.12 3.8 6.3 8.2

2012 Jun 95.76 157.74 208.87 3.2 5.3 7.0

2012 Jul 107.38 180.50 238.97 3.5 5.8 7.7

2012 Aug 120.86 205.86 265.97 3.9 6.6 8.6

2012 Sep 125.00 215.37 274.08 4.2 7.2 9.1

2012 Oct 152.93 251.97 325.83 4.9 8.1 10.5

2012 Nov 138.05 223.05 291.68 4.6 7.4 9.7

2012 Dec 145.88 219.00 307.53 4.7 7.1 9.9

2012 Avge 127.02 209.54 273.81 4.2 6.9 9.0

2011-12 Avge 123.72 203.35 265.19 4.1 6.7 8.7

Table 14: BP-PV monthly generation data – system type averages

The actual annual outputs of the 262 systems per year, and averaged over the two years, are shown in the table below

together with the theoretical Clean Energy Regulator and Sunny Design estimates.

Energiser

1000

(14)

Energiser

1500 (8)

Energiser

2000

(240)

Overall (501.5 kW) %

variation

from

actual Parameter kWh/year kWh/kW/Yr

Total actual output (262 systems)

2011 20231 18927 738918 778076 1551.5

Total actual output (262 systems)

2012 21340 20116 788584 830039 1655.1

Total actual output per annum

2011-12 20785 19521 763751 804057 1603.3 0

Total Clean Energy Regulator

annual estimate 22481 20113 770774 813368 1621.9 + 1.16

Total Clean Energy Regulator

annual estimate with shading 20731 18700 727659 767090 1529.6 - 4.6

Total Sunny Design annual

estimate 23654 22753 811626 858033 1710.9 + 6.7

Total Sunny Design annual

estimate with shading 21809 21169 766334 809312 1613.8 + 0.65

Table 15: BP-PV total annual generation, 2011-12


For the 1000 and 1500 systems the actual two-year average outputs are closest to the Clean Energy Regulator estimate

with shading, but for the 2000 systems, and overall, the actual two-year average output is closest to the Sunny Design

estimate with shading.

Over the 262 systems for two years, the output per installed kW is 1603 kWh/kW/Year, and is closest to the Sunny

Design estimate (with shading) of 1614 kWh/kW/Year (which is only 0.65% higher than the recorded average annual

output). It also compares favourably with the standardised Clean Energy Regulator predictor for zone 1 of 1622

kWh/kW/Year without shading losses.

The results expressed as averages per individual system across the 262 systems are shown below.

Parameter Energiser

1000

Energiser

1500

Energiser

2000

Overall 262

systems

System capacity (kW) 0.99 1.55 1.98 1.91


Total capacity (kW) 13.9 12.4 475.2 501.5

Per system average actual annual output: 2011-12

(kWh/year) 1485 2440 3182 3069

Per system average Clean Energy Regulator annual

estimate (kWh/year) 1606 2514 3212 3104

Per system average Clean Energy Regulator annual

estimate with shading (kWh/year) 1481 2337 3032 2928

Per system average Sunny Design annual estimate

(kWh/year) 1690 2844 3382 3275

Per system average Sunny Design annual estimate

with shading (kWh/year) 1558 2646 3193 3089

Table 16: BP-PV system type annual average outputs

These results provide an acceptable level of confidence in both the operation of these systems and the PV generation

interval data provided by the PWC. The results also indicate that estimates based on the Sunny Design calculator, with

estimated shading losses applied, are the closest to the actual outputs. Although the average outputs for the 1000 and

1500 systems are closer to the Clean Energy Regulator estimates, they are for small numbers of systems, and the

results for the Energiser 2000 systems are considered more reliable, due to the larger number of systems (240). Thus it

is reasonable to conclude that over both a number of systems and a number of years the Sunny Design estimates with

shading losses applied provide a very good estimate of anticipated output from PV systems.

3.3.3 Estimated outputs for all installed BP-PV systems (277)

There were 15 systems for which data was not used in calculations of actual output. For a few of these systems there

were technical issues (e.g. extra panels had been installed during 2011-12, panels had been removed for a period

during renovations), but for the majority there was not 2 full years of data available. Examination of the data for these 15

systems indicated that PV output was within expected parameters, so it is valid to extrapolate the average results to the

15 systems. In the following table, the actual output data for 262 systems is extrapolated to the 277 installed systems.


Parameter Energiser

1000

Energiser

1500

Energiser

2000 Overall

System capacity (kW) 0.99 1.55 1.98


Average actual annual output 2011-12 (kWh/year) 1,485 2,440 3,182 3,069

Number of units installed 14 9 254 277

Extrapolated total actual annual output (kWh/year) 20,785 21,961 808,303 851,050

Total Sunny Design annual estimate with shading

(kWh/year) 856,519

Table 17: BP-PV extrapolated output for all systems

Based on actual generation data, the average annual output of the 277 BP-PV systems, as originally installed, is

expected to be 851,050 kWh/year, only slightly less than the Sunny Design estimate with shading.

3.3.4 Changes in annual electricity use in households with BP-PV

Using quarterly electricity consumption records from the ASC database, average daily consumption (ADC) per registration

was calculated for annual periods before and after the installation date of each BP-PV system. This was achieved using

an innovative reporting tool built in to the database – ‘the ADC analyser’. The steps in the analysis were as follows:

The ADC analyser was run for installed BP-PV system type for one year intervals, for periods of one year before

and two years after the installation date of the system. The resultant data file included the total consumption

and the number of days for which data was available in each year period, and the ADC for each year period

based on these two numbers.

For any one-year period before or after installation, only customers with a minimum of 300 days of data per

period were considered in the analysis. .

For the 2-year period [one year before (BP1) and one year after (AP1) installation], there were 246 customers

with valid data.

For the 3-year period [one year before (BP1) and two years after (AP1 and AP2) installation], there were 239

customers with valid data.

The averages of the individual ADCs across all customers with valid consumption data were calculated.

The results of the ADC calculations for BP-PV customers are shown below

Number of

customers with

valid data

Annual average ADC

across all customers, kWh

Change in annual

average ADC across all

customers kWh

Percentage changes

in ADC

BP1 AP1 AP2 AP1-BP1 AP2-BP1 AP1-BP1

%

AP2-BP1

%

246 23.64 22.69 -0.96 -4.04

239 23.44 22.47 22.15 -0.97 -1.30 -4.13 -5.53

Table 18: BP-PV ADC before & after installation

In the first year after BP-PV installation, on average, there was a 4% decrease in electricity use, and, in the second year a

5.5% decrease, compared to the year prior to installation. No adjustment has been made to take into account other

measures known to have been undertaken by these customers (which may have contributed to a decrease in ADC).

There are two implications from these results:

1 use of the IHD may have contributed to positive behavioural modifications and hence to the decrease; and


2 there was no evidence of a ‘rebound effect’ (i.e. an increase in electricity consumption) as a result of PV installation.

This may relate to their PV installation being one of several energy efficiency measures undertaken.

3.3.5 Household electricity generation compared to electricity consumption

In the CRT Trial report, the interval data used for electricity consumption analyses was for the two year period April 2011

to March 2013. This same two year period has been used for the BP-PV cohort to compare monthly gross generation to

gross consumption aggregated across all the systems for which full monthly datasets were available. The results of this

analysis are shown in the table below.

Year Month

Number of

systems

with data

Gross

generation

kWh

Gross

consumption

kWh

Generation as

percentage of

consumption

2011 April 255 69281.63 125047.2 55.4

2011 May 254 54027.72 160669.7 33.6

2011 June 255 49746.51 200670.7 24.8

2011 July 253 49745.31 191555.5 26.0

2011 August 252 65881.03 138674.9 47.5

2011 September 252 63863.14 127658.8 50.0

2011 October 251 65388.65 148605.2 44.0

2011 November 252 65224.83 164807.9 39.6

2011 December 251 71995.92 208202.9 34.6

2012 January 249 71626.12 225771.6 31.7

2012 February 246 70369.26 183262.9 38.4

2012 March 246 66221.27 148598.6 44.6

Year Total 763371.4 2023526 37.7

2012 April 246 57581.5 144909.2 39.7

2012 May 246 60597.18 153739.9 39.4

2012 June 246 49547.57 188994.6 26.2

2012 July 243 56176.66 203722.5 27.6

2012 August 243 62651.88 153751.3 40.8

2012 September 243 64277.98 127872.4 50.3

2012 October 242 76379.17 149821.2 51.0

2012 November 243 68552.39 194020 35.3

2012 December 240 71658.92 219214.6 32.7

2013 January 241 78349.46 242823.8 32.3

2013 February 241 62584.92 183414.4 34.1

2013 March 239 68216.02 188982 36.1

Year Total 776573.7 2151266 36.1

Table 19: BP-PV monthly gross generation and gross consumption over two years

Over the two years gross generation was 36-37% of gross consumption.

3.4 Effects of Orientation and Other Variables

PV system output may be influenced by a range of interrelated non-system variables, including:

daily solar insolation (affected by level of cloud cover and other aerosols, length of day and position of the sun)

ambient temperature and humidity

wind speed


shading from obstacles present

accumulation of dust and other debris on panels.

System variables that can influence output are:

manufacturing tolerances and panel characteristics

tilt and orientation of panels

cabling/junction factors

inverter factors/performance.

The effects of system variables, including tilt and orientation, were taken into account in both the Clean Energy Regulator

and Sunny Design estimates and are an inherent part of the data. The only non-system variable that was measured as

part of installation was the potential shading losses. This has been discussed earlier and averages 5.7%. However, it

typically represents an estimate from a single point within the area covered by the PV array, and is not static over time,

as trees may grow and increase shading, or may be removed by home owners. In addition, the potential shading losses

were estimated at the time of site assessment and system price quotation, and were not repeated at installation; thus, if

installation was not consistent with site assessment, the shading loss may not be accurate. A survey of actual installation

parameters was not conducted, however anecdotally it is known that at least a few systems were installed at different

orientations to that provided in the quote. Overall, the average shading loss will be considered as reasonably accurate for

the first two to three years after installations were completed.

3.4.1 Actual performance compared to theoretical, including shading

As the Sunny Design estimates appear to be more locally relevant than the Clean Energy Regulator estimates, the actual

annual average generation (January 2011–December 2012) for the 262 systems is compared to theoretical Sunny

Design output including estimated shading losses. This shows that the actual generation is 5,255 kWh per year less than

the Sunny Design estimate. This is only a variation of 0.65% from the Sunny Design estimate.

Theoretical Sunny Design annual generation with

estimated shading losses (Sunny Design ) 809,312 kWh/yr

Actual annual generation January 2011-December 2012 804,057 kWh/yr

Actual annual difference (reduction) - 5,255 kWh/yr

% variation of actual compared to Sunny Design -estimate - 0.65%

Table 20: BP-PV actual and closest theoretical outputs

This variation can be considered within the acceptable error range of the theoretical and actual values, and is a positive

result since the estimated and actual outputs across the 262 systems are so close. However as the Sunny Design

estimate considers location, system specifications, tilt, orientation, and shading losses, it is possible that other

environmental variables may be responsible the approximate 0.65% loss based on the Sunny Design estimated output.

Solar exposure and maximum temperatures for Alice Springs are considered below.

3.4.2 Solar exposure, temperature and monthly PV output

For the 262 systems with data, the average daily outputs per month were normalised by system capacity (kW) across the

three system types, and normalised average daily outputs per month with units of kWh/kW/day were calculated. Average

total monthly outputs per system were also calculated. Solar exposure is the total amount of solar energy falling on a

defined horizontal surface area, per specified time period. Normalised average daily PV generation per month

(kWh/kW/day), and average kWh exported per system per month for the 262 PV systems are provided below, together

with the monthly means for daily global solar exposure and daily maximum temperature – both long-term and for the

months that have PV generation data.


Month

-Year

Average kWh

exported per

System

Normalised

average daily

PV generation

per month

Monthly mean daily

solar exposure

kWh/square

metre/day

Monthly mean daily

maximum

temperature

OC

kWh/kW/day

Average

Long

Term

2011-

2012

Long

Term

2011-

2012

Jan-11 303.30 5.11 7.7 8.4 36.4 37.2

Feb-11 241.96 4.51 7.1 7.5 35.1 33.5

Mar-11 228.33 3.84 6.7 6.1 32.6 28.9

Apr-11 271.54 4.72 5.8 6.5 28.2 27

May-11 213.08 3.58 4.6 4.9 23 21

Jun-11 195.64 3.40 4.1 4.5 19.8 19.5

Jul-11 196.97 3.31 4.4 4.3 19.7 20.5

Aug-11 261.30 4.39 5.3 5.6 22.6 25.4

Sep-11 253.06 4.40 6.2 6.6 27.2 27.9

Oct-11 259.62 4.37 7.1 6.4 30.9 31.5

Nov-11 258.40 4.50 7.6 7.6 33.6 32.7

Dec-11 286.54 4.82 7.7 8.1 35.4 36.4

Jan-12 287.54 4.84 7.7 7.1 36.4 37.6

Feb-12 285.98 5.14 7.1 7.1 35.1 35.6

Mar-12 270.77 3.93 6.7 5.8 32.6 29.8

Apr-12 233.90 4.27 5.8 4.9 28.2 27.9

May-12 245.89 4.13 4.6 4.6 23 23.3

Jun-12 201.27 3.50 4.1 3.8 19.8 19.9

Jul-12 230.15 3.87 4.4 4.2 19.7 19.1

Aug-12 256.38 4.31 5.3 5.2 22.6 24.9

Sep-12 264.33 5.47 6.2 6.1 27.2 29.5

Oct-12 314.34 5.29 7.1 7.6 30.9 33.4

Nov-12 281.38 4.89 7.6 8.1 33.6 36.7

Dec-12 296.19 4.98 7.7 8.3 35.4 37.5

Table 21: Solar exposure, temperature and monthly PV output

For interest, the graph below plots the normalised average daily PV export per month (kWh/kW/day) for the 262 systems

with the monthly means for daily solar exposure, for the period January 2011-December 2012. The period October 2011-

February 2012 was a significant fire season in the Alice Springs district; consequently there were more than normal

levels of airborne particulate matter and periods of reduced visibility.


Figure 2: Solar exposure, temperature and monthly PV output

There is generally a good congruence in the trends of PV generation and solar exposure, which provides further

confidence in the quality of the data. Although the vertical graph scales are set to suit the data, nevertheless on a

relative basis, PV generation trends above solar exposure during the cooler months and below solar exposure in the

hotter months. Panel temperature will generally vary with ambient temperature, which is assumed to represent panel

temperature. It is established that, all other factors being equal, the output of PV panels declines as panel temperature

increases, with the temperature coefficient rating for power output of the BP panels in question being -0.5%/degC.

However solar exposure is generally considered the more relevant factor. Nevertheless for the two-year data series, the

correlations for both solar exposure and mean daily maximum temperature with normalised PV generation were

essentially the same, the coefficients being 0.79 and 0.81 respectively. The correlation coefficient of solar exposure with

mean daily maximum temperature is 0.95 for the two years of data.

3.5 Total GHG Savings from Residential PV

GHG emission reductions produced by the installation of residential PV systems may be calculated by using the

theoretical annual outputs and actual annual output for 2011 and 2012. Based on systems with PV generation data

available (262 systems extrapolated to 277 systems) the theoretical and actual GHG saving are shown in the table

below, using the factors of 0.68 and 0.79 kg CO2 per kWh generated.

If the annual grid electricity consumption at the 277 households that installed BP-PV systems does not increase after the

PV installation (i.e. there is no rebound affect in which overall electricity consumption increases as a result of the PV

generation ‘buffer’), then there would be a reduction in demand on power generation by the PWC (of 850,000

kWh/year), with a consequent annual reduction in GHG emission in the order of 579,000 kg/year, or if fossil fuel

transport and transmission losses (scope 3) are taken into account, 672,330 kg/year.


Total installed capacity - 277 systems -

530.7 kW

Annual

generation

kWh/Yr

Potential GHG

emission

reduction Kg/Yr

(0.68 kg/kWh)

Potential GHG

emission

reduction Kg/Yr

(0.79 kg/kWh)

Clean Energy Regulator theoretical

optimum annual generation 860,844 585,374 680,067

Clean Energy Regulator theoretical annual

generation with estimated shading losses 811,684 551,945 641,230

Sunny Design theoretical optimum annual

generation 908,224 617,592 717,497

Sunny Design theoretical annual

generation with estimated shading losses 856,519 582,433 676,650

Actual annual generation: Jan 2011 – Dec

2012 extrapolated to 277 systems 851,050 578,714 672,330

Table 22: BP-PV greenhouse reductions

3.6 Direct PV Costs per Output Units

The total cost of PV installations and the direct cost to the ASC are related to the annual kWhs saved and to the GHG

emissions reduced, for one year and for 15 years, the latter being the deeming period for PV systems. For example the

total cost per kWh saved over 15 years was $0.47, and the ASC cost was $0.18.

Per year initially Per 15 years

Total cost ASC cost Total cost ASC cost

Annual parameter

Annual

Savings

$6,008,967 $2,334,065 $400,597.80 $155,604.33

Cost per unit – one year Cost per unit – 15 years

kWh generated/saved 851,050kWh 7.06 2.74 0.47 0.18 $/kWh

GHG emissions Scope 1

saved 578,714kg 10.38 4.03 0.69 0.27 $/kg

GHG emissions Scope 1 and

3 saved 672,330kg 8.94 3.47 0.60 0.23 $/kg

Table 23: PV costs per unit kWh and GHG savings

3.7 Performance of Inverter Upgrade

A number of customers chose to upgrade the size of the standard packaged inverter, from the SMA SB1700 to the SMA

SB2500. This was either on the basis of having the option to add additional capacity at a later date, or on the advice

from other sources that the inverter was undersized for the capacity of the panels being provided (the nominal capacity

of the Energizer 2000 package was 1980W, and the maximum AC output rating of the SB1700 is 1700W). The upgrade

price for the larger inverter was $1000 to $1500 (representing inverter, warranty, cabling and circuit breaker cost

increases), and was not eligible for ASC incentive.

Analysis of the performance of systems operating in 2012 is presented below. 2012 was chosen because of the

minimum number of data issues in that year. There were 24 systems recorded as having the SB2500 inverter, and these

generated on average 3427 kWh per annum, 5.5% more output on average than systems with the SB1700 inverter. In


addition, six of the systems marked as SB1700 had a peak output record during the year that was noticeably higher than

the theoretical limit of the SB1700. These averaged 3505 kWh per annum, 8% higher than the standard SB1700

installs. Assuming these 6 were in fact SB2500 installations (this was confirmed verbally for one customer), then the

generation by SB2500 installations was on average 6.1% above the average for the SB1700.

Customers who upgraded to the SB2500 inverter were therefore generating approximately 200 kWh per annum more

than the standard install.

Inverter Number of

Systems

Total Annual

Generation

Average

Annual

Generation

Highest

maximum

export reading

Average

maximum

export reading

% of

SB1700

inverter

SMA SB1700 213 690987 3244 1.764 1.69 100.0%

SMA SB1700? 6 21031 3505 1.91 1.85 108.0%

SMA SB2500 24 82240 3427 1.88 1.73 105.6%

Grand Total 243 794258 3269 1.91 1.70 100.7%

Table 24: Analysis of performance of Energizer 2000 by inverter type (2012 data)

4. Residential PV buyback

To gain feedback about customers’ experiences with, and views about, their BP-PV systems, and to provide data for

reporting, a short survey was circulated to all customers who had installed BP-PV. The survey was made available at the

end of the first week in October 2011 and the return period closed on October 31 2011 – the survey was conducted

approximately 15 months after the final PV system was installed, so the majority of participants would have had

operational systems in place for at least 18 months. For all customers who had an email address, the survey was made

available on line, and those without email were posted a printed copy with a reply paid envelope. From the original 277

participants, the return rate was 40% (110 responded, a small number of whom had moved out of their residences. The

survey is available in Appendix 2.

In formulating the survey, it was decided not to ask questions directly about the influence of the elevated buyback on the

decision to purchase BP-PV. The wording and structure of the questions aimed to avoid leading respondents on this

factor. In analysing open response questions, categories were generated and response elements allocated accordingly.

4.1 PV System Uptake and the Influence of the Elevated Buyback Tariff

There were a number of factors both technical and social that related to the uptake of the BP-PV systems, the target for

which (as peak kW output) was exceeded by nearly 80%, (target: 300 kWp, actual: 535 kWp). The relevant technical

factors influencing uptake were:

an informative quotation

the high quality of all the components of the BP system, and the associated long-term warranties

for the relevant period (2008-2009), the reasonable net cost to the purchaser, given the associated subsidies

(approximately $8000 upfront for a quality 2kW system with a then market value of approximately $20,000)

the elevated buyback tariff for the gross electricity generation from the system until May 2013

the inclusion of an IHD as part of the package

a one year post-installation system check.

In initial discussions with customers and in the associated provision of print information, the elevated buyback tariff was

just one of the factors described or discussed for consideration by potential purchasers. It was not afforded special

prominence among the factors outlined above, and as such customer awareness of its specific details was expected to

be varied.


After a very slow initial uptake during 2008 and early 2009, there was a sudden increase in demand for ASC BP-PV

systems, which became somewhat of a social phenomenon in Alice Springs during the latter part of 2009. Through

quotations and ASC approvals, the funds available to incentivise BP-PV systems were committed by the end of 2009.

With only one installer engaged by BP, there was a lag-time between approval and installation, but the installations per 6

month periods show the slow initial uptake and the subsequent surge.

Number of ASC BP-PV installations per period

Mar-Jun 2008 Jul-Dec 2008 Jan-Jun 2009 Jul-Dec 2009 Jan-Jun 2010 Total

2 24 34 84 133 277

26 118 133

Table 25: Number of ASC BP-PV installations per period

It is likely that two factors contributed to this surge:

1 from mid 2009, part of the ASC marketing campaign for ASC BP-PV highlighted the fact that limited incentive funds

were available and that the PV program was coming to a close; and

2 it also appeared that the number of residents with awareness and knowledge about the value and benefits of

rooftop PV had reached a critical mass, and hence ‘word of mouth’ was a significant factor. The demand exceeded

the available funds, and a large number of motivated ASC customers missed out on installing a BP-PV system. Many

of these customers, (together with non-ASC customers), installed PV systems at a later date through contractors

working outside the ASC program.

4.1.1 Relevant results from the BP-PV survey

Relevant questions and their responses are provided in this section together with interpretive comments. There were no

direct questions about the influence of the elevated buyback tariff.

5a. How well do you understand the residential PV buyback tariff

associated with your PV system?

Valid Responses

Response Number %age

Not at all 5 4.7%

A little 54 50.4%

Well 48 44.90%

Total 107 100.0%

5b. Please briefly explain your understanding of the buyback tariff

Response category Valid Responses

Number %

PV generation is purchased at an elevated rate 57 41.3

PV generation is purchased at a standard rate 1 0.7

PV generation is purchased at a lower rate 1 0.7

PWC purchase (credit) generation when generation exceeds 17 12.3


household electricity use

The household pays for all electricity consumed, and receives a

credit for all electricity generated 40 29.0

Household electricity consumption is billed according to the CRT 20 14.5

Other 2 1.4

Total 138* 99.9

* Open response question- there were 95 respondents some of whom provided more than one aspect of understanding.

Table 26: Survey responses - understanding of the buyback tariff

The responses to these two questions indicate that, at best, 45% of respondents had an accurate understanding

of the nature of the elevated buyback tariff.

The types of understanding of the tariff, together with 50% of respondents having ‘a little’ understanding of the

tariff, indicate that there are a number of misconceptions about the nature of the elevated buyback tariff.

1. Please list in priority order the reason or reasons why you wanted to install the ASC-BP PV

system:

Response category

Valid Responses

Number %age

Save money by reducing electricity costs 80 37.4%

Address environmental concerns 76 35.5%

System package and/or financial incentives available 21 9.8%

Support ASC and/or the PV (renewable) industry 16 7.5%

Monitor and reduce household electricity consumption 7 3.3%

Personal interest 8 3.7%

Other 6 2.8%

Total 214* 100.0%

* Open response question - there were 108 respondents many of whom provided more than one reason.

Table 27: Survey responses -reasons for installation of BP-PV

Most respondents (80 out of 110, or 73%) provided a response in the category ‘Save money by reducing

electricity costs’, and for 59 (75%) of these it was the first or only reason listed.

The most common generic reason in the ‘Save money by reducing electricity costs’ category was about saving

money/reducing costs of power bills, with an apparent implicit assumption that electricity use from the grid

would be reduced.

Only 4 of the 108 respondents directly mentioned the benefits of the elevated buyback tariff.

The three economic reasons (save money by reducing electricity costs, system package &/or financial incentives

available, monitor and reduce household electricity consumption) constituted only 50% of all the 214 reasons

provided. (in contrast to 75% of the respondents); environmental aspects rated highly.


2. What has been your level of satisfaction with the following aspects of your PV installation?

None-1 Low-2 Medium-

3 High-4 Total Statistics

No. % No. % No. % No. % No. % Mean Sunny

Design

d. The ongoing operation

of the PV system 1 0.9 3 2.7 18 16.4 88 80 110 100 3.75 0.545

e. The usefulness of the

IHD 2 1.8 14 12.7 31 28.2 63 57.3 110 100 3.41 0.782

f. The economic benefits

of the PV system 2 1.8 1 0.9 25 22.9 81 74.3 109 100 3.7 0.585

Table 28: Survey Responses - Satisfaction with BP-PV

After 18 months to 2 years of using the system, the majority of customers are satisfied/very satisfied with both

the operation of their system and the economic benefits it has provided.

3a. If you moved to a house without a PV system, would you consider installing a new

PV system?

Response Valid Responses

Number %

Yes 103 94.5

No 6 5.5

Total 109 100.0

Q3.b Based on your previous knowledge/experience, what would be the key factors

influencing your decision?

Response category Valid Responses

Number %

Cost of system and available rebates/incentives 38 37.4

Economic benefit to household 52 35.5

Installers, system quality and size 21 7.5

Environmental benefits 30 9.8

House/property characteristics 17 3.3

Ability to monitor household electricity consumption 6 3.7

Other 4 2.8

Total 168* 100.0

* Open response question - there were 107 respondents many of whom provided more than one factor.

Table 29: Survey responses - consideration of PV for new property

In a new/different residence, 95% of respondents would consider installing a new PV system.

Most respondents (84%) selected the financial categories ‘Cost of system and available rebates/incentives’ and

‘Economic benefit to household’, and for 68 (64%), these were the first or only factors listed.

The two financial/economic factors constitute 73% of the 168 factors provided.

Only 12 of the 107 respondents directly mentioned the potential benefits of a possible elevated buyback tariff

associated with a new installation.


4. Are your electricity bills generally in credit?

Valid Responses

Response Number %

Yes 75 70.1

No 32 29.9

Total 107 100.0

Table 30: Electricity bills in credit

Many respondents (70%) indicated that their electricity bills are generally in credit. In the majority of these cases

it is likely that this was due to the elevated buyback tariff.

4.1.2 Conclusions from the BP-PV survey

Economic factors were the primary influence on the decision to install BP-PV. However, there was strong

acknowledgement of the environmental benefits.

The main economic/financial factors were associated with the large incentive/subsidy available for a quality

system (with warranties), and the potential future reduction in the cost of electricity bills, with limited post-

installation mention of the contribution of the elevated buyback tariff.

There were high levels of satisfaction with system performance and the economic benefits.

A large proportion of respondents had electricity bills in credit, likely to be largely attributable to the elevated buy

back tariff.

There was little direct acknowledgement of the elevated buyback tariff in either reasons for wishing to install a

system, or factors that would influence consideration of PV in a new/different home without PV.

The elevated buy back tariff was not a prominent factor in customer’s minds when they responded to this

survey, although it may have been more important at the time of making the decision to purchase a BP-PV

system, especially as it was part of the information supplied to them. Overall it would appear that the elevated

buyback tariff was one financial factor among several that influenced the decision to go ahead with BP-PV

installation. The responses point to it being a less important factor than the major incentive/subsidy available

for a quality system, and the long term generic reduction in use of grid electricity with associated financial

savings.

4.2 Success and Cost of PV Buyback Tariff

The conclusions in 4.1.2 above indicate that the elevated buyback tariff was only one economic factor among several in

influencing decisions and therefore was not the major factor. It can be considered moderately successful in promoting

PV uptake in the ASC program, and significant ASC funds were used to support the buyback tariff.

A more objective measure of its use is associated with the cost of the elevated buyback tariff to ASC during the course of

the program. PWC included the elevated buyback tariff as a credit on customer’s quarterly electricity invoices. The

customers had to be the original purchasers of a BP-PV system to be eligible for the elevated buyback. During the first

two years of the PV installations (2009-10) PWC billing to ASC was intermittent, as a consequence of the metering and

billing issues referred to previously (see section 2.1.5); however, in the final 2-3 years, ASC generally received copies of

the quarterly invoices after each quarter that BP-PV customers were billed. The ASC contribution to the tariff was fixed at

22.65 cents per kWh over the course of the program. The ASC payments to PWC for the ASC portion of the elevated

buyback to Nov 30 2012 are shown in the table below, together with the potential ASC cost for the total PV generation to

that date.


Nature of potential ASC contribution to elevated buyback tariff Cost

1. Theoretical - Potential elevated buyback payments by ASC to PWC until Nov 30 2012,

at 22.65 cents per kWh gross PV generation, based on data for total PV generation for all

BP-PV systems installed

$564,286

2. Actual - Total elevated buyback payments by ASC to PWC until Nov 30 2012, at 22.65

cents per kWh gross PV generation from systems of original purchasers of BP-PV systems

$497,457

3. Difference between 1 and 2 $66,829

Table 31: Actual and potential cost to ASC of the elevated buyback tariff

The difference between the actual and potential costs to ASC largely represents the electricity generated by systems on

premises that were sold by the original installers of the BP-PV (after which new owners did not receive the elevated

buyback), together with other idiosyncrasies, such removal of a system for a year during home renovation, and a type 2

metering arrangement, which measures net rather than gross PV generation.

The ASC contribution to the elevated buyback represents an average contribution to each the 277 purchasers, of $1,796

to Nov 30 2012. This is a significant additional subsidy to the incentives provided at purchase.

5. Learnings and Issues

5.1 Program Design

Alice Solar City's choice of a sole supplier leveraged the industry experience and capacity of Australia's most established

solar company and its only solar PV manufacturer. However, the long term nature of the contractual arrangement limited

the ability to respond to a rapidly changing market, and did not provide the responsiveness and flexibility that may have

been better achieved with multiple suppliers.

Alice Solar City's provided a small set of pre-designed packages to make selection easy for its customers. However a

number of real world concerns impacted on this limited packaging, including the need to cater for flat roofs which had to

be addressed as the program progressed. Alice Solar City's decision to not fund inverter upsizing caused some conflict

with customers who felt that the system design was flawed, based on local word of mouth and incorrect interpretation of

technical information.

Alice Solar City arranged to streamline the normal PWC paperwork involved with grid connection through a single

registration form. Ultimately however Alice Solar City had to facilitate the completion of the full paperwork, and it may

have been more efficient to have focused on streamlining completion of the full paperwork in the beginning.

5.2 Decision to Purchase PV

Homeowners were interested in intricate details of PV system economic and payback arrangements before signing up.

This was not surprising given the system choices being offered, the complexity of the future value of the elevated

buyback, and the overall size of the upfront investment ($10,500 net to the household).

Homeowners were interested in how the value of PV systems would affect property prices. There was a need to tailor

information to those who were likely to sell-on within the life of the program and who were therefore interested in how

their PV system could add value for potential home purchasers.

Inverter size was an issue (addressed earlier in this report).

5.3 Installation of PV

ASC and BP initially planned for a local contractor to be selected to be trained and to deliver all installations under the

program, in order to ensure local content and local industry development. This proved to be a bottleneck to the rollout,

and eventually an additional installer, from a separate contractor who had a better working relationship with BP, was

relocated to Alice Springs.


There was initial concern about the inverters being placed outside, and the first few installations therefore placed the

inverter inside the home. This proved to cause a serious noise problem, and those inverters were subsequently relocated

to shaded exterior locations. Extra effort should be made to site inverters well away from living areas. Similarly they

should not be mounted on hollow walls if at all possible so as to avoid potential noise reverberation within the house.

Several customers signed up to have a BP package installed on a house that was planned to be built or under

construction. Delays in the building resulted in delays in PV installation, with the last of these being connected to the grid

in 2011 – 1.5 years after funding was offered.

Aspects considered earlier in this report under ‘Technical Information’:

tilt frame

IHD communication

requirement for building permit

metering

rural customers

An example of one unusual situation: the original local BP subcontractor arranged for a donation by BP of a complete

system as part of the ASC project to a young mother who had lost her husband in difficult circumstances. By the time this

was approved, the young lady had moved temporarily into her parent’s home, where the system was eventually installed.

The parents in turn moved out not long thereafter, with the result that the donation provided little direct benefit for the

original intended recipient.

5.4 Operation and Maintenance of PV

The BP contract included a 12 month follow up maintenance visit. This proved to be a valuable opportunity to ensure that

customers had received manuals and paperwork, to rectify any minor issues and to apply changes to the inverter

programming to ensure compliance with PWC requirements. It is unlikely that this reprogramming and rectification would

have occurred without the 12 month maintenance visit locked in.

In early 2010 ASC arranged for the CEC to conduct an audit of selected solar power installations around Alice Springs.

The results were largely positive. Minor issues identified by the audit such as the use of conduit with limited UV

stabilisation were in many cases able to be addressed as part of the BP maintenance visits or else thereafter.

Flat roofs, in addition to posing a problem for the selection of a suitable tilt frame, caused additional issues in the

potential for the build-up of leaves and other debris against the mounting system, impeding the already slow drainage.

This was exacerbated by the difficulty in accessing detritus built up underneath long arrays.

PWC requirements for grid connection included the need for a wider operating frequency range, particularly useful on

smaller isolated grids like those in Alice Springs where deviations from the standard electrical frequency of 50Hz are

more common, and indeed are a potential load reduction tool for dealing with emergency load situations. Ensuring that

inverters were pre-programmed or programmed in situ to meet these requirements was difficult to enforce and monitor.

As the ASC program was the first significant residential PV project undertaken by the PWC, there were some initial

difficulties associated with the Smart Meter software, involving data capture and transfer. Thus for some properties, valid

and reliable interval data did not become available for periods of up to 10-12 months after smart meter installation.

Once identified, these issues were promptly resolved, and reliable data become available until the end of the program.


6. Appendices

The appendices, with a title page for each, are in the following un-numbered pages

t

Residential PV

Appendices

Residential Overview Appendices 1

Table of Contents

Appendix 1 ........................................................................Grid connection wiring diagrams

Appendix 2 .................................................................................Survey of BP-PV customers

Residential PV

Appendix 1

Wiring Diagrams

Existing Service Fuse

(Overhead area)

Existing Switch Board

Lockable Isolator adjacent to

Inverter

Neutral

Meter Box on House

Existing Power and Water Network

(1 phase 80A supply)

Neutral Bar

DC AC Inverter with in-built protection

Solar City - Typical Rural Single Phase Supply, Single Phase PV System Connection and Metering SchematicCustomer: Address: Lot No:

Lockable DC isolator adjacent to the array (AS5033 clause 2.5)

Lockable DC isolator adjacent to Inverter (AS47777, clause 5.4)

Existing Service Fuse1

(Underground area)

Import/Export kWh meter

(single phase)

Existing Meter Box at front Boundary

Inverter

PV Array

L N Dual Element

kWh meter (single phase)

Load 1 N Load 2

Existing Service Fuses

(Overhead area)

Three phase Import

kWh meter (Redundant)

Export kWh Meter

(single phase)



Inverter

Neutral

Meter Box on House



Neutral Bar


Solar City - Typical Rural Three Phase Supply, Single Phase PV System Connection and Metering SchematicCustomer: Address: Lot No:




(Underground area)

Import/Export kWh meter

(three phase)

Existing Meter Box at front Boundary

Inverter

PV Array

Existing Service Fuse

(Overhead Area only )

L N Dual Element

kWh meter (single phase)

Load 1 N Load 2



Neutral


(single phase 80A supply)

100 Amp Service fuse in Meter Panel


Solar City -typical Single Phase PV System Connection and Metering Schematic Customer: Address: Lot No:

Lockable Isolator/circuit breaker adjacent to Inverter


Inverter

PV Array


(Overhead area)

New Import kWh meter

(three phase)

New Export

kWh Meter (single phase)



Inverter

Neutral

Meter Box



Neutral Bar

100 Amp Service fuses in Meter Panel


Solar City - Typical Three Phase Supply, Single Phase PV System Connection and Metering Schematic Customer: Address: Lot No:



Inverter

PV Array

Residential PV

Appendix 2

BP-PV survey

BP PV – Views about your PV System 2011 RID: 391 Please first read the accompanying letter/information sheet ‐ person most involved with/interested in to respond. We appreciate your answering the questions thoughtfully and honestly – where relevant, please circle the number next to the answer of your choice, e.g. 3 We value highly your comments and views.

1. Please list in priority order the reason or reasons why you wanted to install the ASC‐BP PV system:

Level of satisfaction 2. What has been your level of satisfaction with the following aspects of your PV installation? None Low Medium High

a. The assessment and quotation process 1 2 3 4

b. Dealing with Alice Solar City 1 2 3 4

c. The installation of the PV system 1 2 3 4

d. The ongoing operation of the PV system 1 2 3 4

e. The usefulness of the In‐house display 1 2 3 4

f. The economic benefits of the PV system 1 2 3 4

g. The environmental benefits of the PV system 1 2 3 4

h. Other …………………………………………………………….. 1 2 3 4

Please make any suggestions or comments for improvement:

3. If you moved to a house without a PV system, would you consider installing a new PV system?

1. Yes 2. No

Based on your previous knowledge and experience, what would be the key factors influencing your decision?

4. Are your electricity bills generally in credit (i.e. with your PV system, you earn more than you spend on electricity)?

1. Yes 2. No

5. How well do you understand the residential PV buyback tariff associated with your PV system?

1. Not at All 2. A little 3. Well

Please briefly explain your understanding of the buyback tariff:

5. In regards to your household, how did you view the compulsory change from the flat rate tariff to the Cost Reflective Tariff (peak and off‐peak times)?

Very negative 1 2 3 4 5 Very positive

6. Did you borrow 30% or more of the cost of your PV system?

1. Yes 2. No 3. No Response

THANK YOU FOR YOUR TIME and INTEREST. Please return the completed survey in the envelope provided by the 31st October, 2011 to be entered into the draw for a $100 gift voucher.

residential photovoltaic systems · residential photovoltaic systems 2 if the quotation was...

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