Inverter performance models Opportunities and requirements for the future

Jaspreet Singh, PG Solar, May 5th 2014

© ABB May 05, 2014 | Slide 1

2 Confidential © ABB May 05, 2014 | Slide 2

A global leader in power and automation technologies Leading market positions in main businesses

145,000 employees in about 100

countries

$39 billion in revenue (2012)

Formed in 1988 merger of Swiss and

Swedish engineering companies

Predecessors founded in 1883 and

1891

Publicly owned company with head

office in Switzerland

Solar PV

applications

Product,

system and

solutions

offering

Solar inverters Low voltage products PV power plants Products and solutions

for trackers Grid integration

• Micro inverters

• String inverters – single

phase

• String inverters – three

phase

• Central inverters

• Turnkey inverter solutions

• Switching (switch-

disconnectors, circuit

breakers, contactors)

• Protection (miniature-

circuit breakers, residual

current devices, fuses,

surge protective devices

• Metering and monitoring

• Combiner boxes

• Other (terminal blocks,

pilot devices, etc).

• Turnkey, balance of

system (BoS) and eBOP

(electrical balance of

plant) offering

• Remote operations and

maintenance, SCADA

• Plant automation and

optimization

• Brake motors

• DC motors

• Drives

• PLCs

• Manual motor starters

• LV breakers and switches

• PLC peripheral products

(monitoring relays, timers,

power supplies, serial

data converters, interface

relays, opto couplers…)

• Turnkey substations

• Compact secondary

substations (CSS)

• Transformers

• Medium voltage

switchgear

• FACTS

• HVDC power transmission

Related

offerings

ABB in solar: Most comprehensive value proposition Full range of products and solutions for key applications

Microgrids Residential Commercial Utility

Smart grids Electric vehicle charging Battery energy storage

4 Confidential

External tools

CEC efficiency - Sandia guidelines, factory witnessed

CEC efficiency - includes auxiliary power

OND files - certified by 3rd party IE partner

Post processing tools - simplified Excel files with derating

factored

Derating plots - temperature, voltage, altitude

Internal tools

Inverter models - coefficients for temp/voltage derating

Array model - single diode equation models from public

data

Combined model to spot check and approve applications

Inverter performance models What we share

© ABB May 05, 2014 | Slide 4

5 Confidential

CEC efficiency

Revised Sandia guidelines

Auxiliary load Inclusion

Thermal derating

Ambient temperature

Solar gain

Voltage derating

DC input voltage

Power factor operation

Voltage dependence

Temperature dependence

Inverter performance models Opportunities

© ABB May 05, 2014 | Slide 5

6 Confidential

DC/ AC ratios

Derating

Efficiency

Multi MPPT configurations

Different orientation

Variable conditions

MPPT Efficiency

Static

Dynamic

Inverter performance models Opportunities

© ABB May 05, 2014 | Slide 6

7 Confidential

Multiple manufacturers

Large product portfolios

Multiple topologies

Different thermal designs

Different coefficients

Extensive testing

Data validation

Inverter performance models Complexities

© ABB May 05, 2014 | Slide 7

8 Confidential

Initial models can be created based on design parameters

Final modified models can be based on measured data

Irradiance and other application effects need to be discussed

Inverter performance models Thermal derating

© ABB May 05, 2014 | Slide 8

9 Confidential

Nominal power window and operating windows may be different

Temperature dependence on operating voltage need to be

discussed

Inverter performance models Voltage derating

© ABB May 05, 2014 | Slide 9

10 Confidential

Inverter output power ∝ inverter internal temperature

Inverter temperature = α1 x ambient temperature + solar

gain

Solar gain = irradiance (W/m2) x solar absorption (%) +

surface area (m2)

Inverter output power ∝ DC input voltage

DC input voltage = f (array voltage, MPPT operating point)

Array voltage = f (temperature, irradiance, Rsh)

Inverter performance models Developing a model

© ABB May 05, 2014 | Slide 10

11 Confidential

Modeled PV array using single diode model and inverter

derating model

Focus is on approving applications rather than energy

harvest

Inverter performance models Developing a model

© ABB May 05, 2014 | Slide 11

12 Confidential

A common industry benchmark is recommended

Phase approach can be used

Scientific community needs to support

Inverter performance models Phase approach

Derating models

• Existing data

Efficiency • New standards

• New testing

Applications • Power factor

• Grid support

• CPUC Rule 21

© ABB May 05, 2014 | Slide 12