to: andrea arnold, city manager cc: from: date

Public Works Department 2635 Talley Street

Decatur, Georgia 30030

404-370-5571 • Fax: 404-378-4153 http://www.decaturga.com

MEMORANDUM

TO: Andrea Arnold, City Manager

CC: David Junger, Assistant City Manager

FROM: David Nifong, Lead for America Fellow

DATE: March 11, 2021

RE: Application for GEFA Solar Resiliency Program

The purpose of this memorandum is to recommend the authorization of an application to the

Georgia Environmental Finance Authority’s (GEFA) Solar Resiliency program.

In June 2020, the City of Decatur was accepted to participate in phase one of the Solar

Resiliency program. Working with GEFA’s contracted consultants, GDS Associates Inc., the City

received technical assessments for the installation of solar photovoltaic (PV) arrays and battery

storage systems at the Decatur Recreation Center and the Public Works building. These systems

were sized to meet the electricity demand of each facility’s critical loads during emergency

operation scenarios.

The second phase of GEFA’s Solar Resiliency program offers grant funding to municipalities to

incentivize the installation of solar PV and battery systems. After evaluating each assessment, it

is recommended that the City apply for funding to complete an installation at the Public Works

Building. The assessment showed that a roof-mounted 100 kW solar array and 35 kW lithium-

ion battery will have the capacity to maintain the facility’s critical functions for a 36-hour

outage, including vehicle fueling and maintenance. Supporting the operation of the first

responders’ fleet, such as patrol cars and firetrucks, is vital to the City’s response to emergency

scenarios. During non-emergency scenarios, the system will be able to meet approximately

one-third of the facility’s electricity demand with on-site renewable energy.

The system described above has an approximate cost of $500,000, including necessary

electrical engineering and infrastructure upgrades. If approved for funding, the City will invoice

GEFA for reimbursement of up to $200,000 of equipment and labor. The net cost to the City

would be approximately $300,000. Assuming electricity consumption at the facility remains

stable, the project costs will be recouped in approximately 10 years through energy bill savings.

It is recommended that the City Commission authorize the application for the second phase of

GEFA’s Solar Resiliency Program as described above.

Decatur Public Works

Building

Resiliency Feasibility Study

March 10, 2021

GEFA GEORGIA ENVIRONMENTAL FINANCE AUTHORITY

P R E P A R E D B Y G D S A S S O C I A T E S , I N C .

1850 Parkway Place Suite 800 Marietta, GA 30067 770-425-8100 Fax 866-611-3791 www.gdsassociates.com G e o r g i a Te x a s A l a b a m a N e w H a m p s h i r e W i s c o n s i n F l o r i d a M a i n e Wa s h i n g t o n O r e g o n

March 1, 2021 David Nifong Department of Public Works City of Decatur 509 North McDonough Decatur, GA 30030 RE: Solar Resiliency Analysis Dear Mr. Nifong: The Georgia Environmental Financing Authority (“GEFA”) and GDS Associates, Inc. (“GDS”) appreciate the opportunity to visit the Public Works building in Decatur, GA. Attached is the first draft of the Solar and Battery Resiliency Feasibility Study for the facility. This study summarizes our initial findings and analysis with regards to the resiliency options for the facility. The price and performance information presented is analytical and may not align with vendor price quotes or proposed design. We welcome your feedback and request the opportunity to present the report in a short meeting to be coordinated at your convenience. Sincerely, Sincerely, Rich Polich Josh Duckwall GDS Associates, Inc. GDS Associates, Inc.

GEORGIA ENVIRONMENTAL FINANCE AUTHORITY Feasibility Study 3.10.21

prepared by GDS ASSOCIATES INC i

TABLE OF CONTENTS

1 PROPOSED SITE ................................................................................................................................. 2

Site Description .......................................................................................................................................................................................... 2

Critical Loads .............................................................................................................................................................................................. 3

Suitability Factors ...................................................................................................................................................................................... 4

2 RESILIENCY SOLUTION ..................................................................................................................... 6

Targeted Outage........................................................................................................................................................................................ 6

Load Profile.................................................................................................................................................................................................. 6

Solar ............................................................................................................................................................................................................... 6

Battery ........................................................................................................................................................................................................... 7

Performance Model .................................................................................................................................................................................. 8

3 PROJECT ECONOMICS....................................................................................................................... 9

Economic Model ......................................................................................................................................................................................... 9

Solar Economics ......................................................................................................................................................................................... 9

Battery Economics ................................................................................................................................................................................... 10

4 PROJECT RECOMMENDATIONS ..................................................................................................... 11

Project Options ......................................................................................................................................................................................... 11


prepared by GDS ASSOC IATES INC 2

1 Proposed Site

SITE DESCRIPTION

1.1.1 Building

The Decatur Public Works Building is an approximately 33,000 square foot, 3-floor facility situated on Talley Street near downtown Decatur. Administrative office space, an IDF/server room, storage areas, a kitchen/breakroom, and a large maintenance garage make up the primary interior spaces. On the exterior there are three vehicle fueling pumps for unleaded and diesel city fleet. The computer/office space on the main floor can be used as a temporary command center in a power outage, and it is currently capable of being powered by the onsite generator. The building is focused on providing essential services and in an outage, would likely not serve as a shelter or warming center to the general public. The priority equipment is largely IT based, with some equipment in vehicle servicing that would be advantageous to have active during a power outage such as compressed air and associated tools, vehicle management computer systems, and other equipment that will be utilized and considered critical to the City in an outage, located in the utility room and main office area.

1.1.2 Utility Data & Load Description

The Public Works building is served by Georgia Power under a Power and Light Small commercial rate. Monthly load and energy consumption data was acquired through the site contact and confirmed through the utility billing system. The period of January – December 2019 was selected for the analysis. The energy consumption patterns of the building for the 12-month period of Jan 2019 – December 2019 are shown below. Due to the pandemic, energy behavior patterns in 2020 were excluded from consideration in the analysis.



1.1.3 Location

The Decatur Public Works building is just outside of downtown Decatur, Georgia, and is located at 2635 Talley Street Building A, off College Avenue.

CRITICAL LOADS

1.2.1 Identification

GDS Associates submitted a formal data request to the site management as part of the kickoff process to gather preliminary information on the loads considered critical for a power outage. The data request covers the operational and equipment details that are available to transmit to GDS prior to the site visit, including utility information and any existing resiliency features. The intention is to use the self-identified critical loads as a focus of the site visit and analysis, for which energy consumption in a critical event is desk calculated, following the site visit, and adjusted to energy behavior that is typical of the performance in a critical event. The City provided a substantial amount of information in the data response including electrical diagrams, utility bills, solar equipment details and quotes, and facility operation information. For this facility, it is expected that normal operations will undergo a shift as the facility contains space that can operate as a temporary command center for the city’s public works department. The fuel pumps, servers, security system, and a portion of the administration office space are considered critical. A limited number of HVAC systems, lighting, computer systems, and kitchen equipment will need to operate during the critical event under patterns that are atypical. The concept of incorporating a DC Fast Charger (ABB Terra 184F) for future use on electric fleet vehicles was analyzed for consumption of backup battery power and shown to be prohibitive as it would nearly quadruple the size of the battery. The ideal electric vehicle charger may exist and further research is recommended. A preferred product would likely be able to charge in a reduced capacity similar to a level 2 charger, something that DC fast chargers are not commercially known for being able to do. A preliminary list of major electrically powered equipment that is targeted for analysis in the critical event scenario is shown below:

Lighting 3L 4' Super T8, T5



HVAC Daikin VRV heat pump/minisplit system

Aux 5 HP Compressor

IT Computer/Server blades (standard consumption)

Exterior Fuel Pumps (2 Unl., 1 Dies)

Kitchen Standard spec side by side, ice maker

Exhaust hood Greenheck (spec)

1.2.1 Energy and Demand of Critical Equipment

GDS performed a measure level analysis of power consumption and demand for the eligible equipment using a combination of nameplate information and industry standard technical reference variables. The focus of this effort is to provide a sanity check for the critical load percentage applied to the load shape later in the resiliency model software. Critical equipment was identified in the initial site meeting and walkthrough, and assumptions on equipment behavior are estimates. Not all equipment included in the site audit is expected to run during the critical event, so assumptions were made to reduce the number of operating HVAC systems or hours and limit the use of the remaining equipment in order of priority. All critical IT equipment is expected to run as normal, as well as kitchen equipment. For purposes of this facility, a 36-hour outage was considered for analysis. For the equipment listed above, as analyzed in a 36-hour outage, the

approximate demand would total 30.6 kW at peak demand the energy consumption over the 36-hour period would be estimated at 373 kWh using nameplate performance data. This performance corresponds to a critical utilization of approximately 50% of the normal consumption of some of this equipment in a summer month, the targeted critical outage season, with the solar arrays performing optimally and in concert with the battery.

SUITABILITY FACTORS

1.3.1 Energy Efficiency Issues

The Public Works facility has a number of features that show attention to both energy efficiency and occupant workspace suitability. The envelope of the building has incorporated a number of solar tubes and skylights for natural daylighting, shown to both improve workplace satisfaction and reduce lighting cost in commercial office spaces like the one in the upper floor of the public works building. Further, multiple and smaller HVAC zones have been incorporated into the building and this is a much more efficient way to cool and heat the offices as compared to large and uncontrolled centralized heating and cooling. The overall mechanical, electrical, and plumbing features of the facility and considered to be adequately efficient, particularly the VRV system, but still have room for improvement in terms of equipment efficiency ratings. The lighting is efficient super T8 or T5 florescent with some LED, so it is recommended to explore additional LED retrofits in the near future.



1.3.2 Solar Suitability

The property has ample rooftop space without obstructions for solar, approximately 15,000 gross square feet, but limited ground mount space outside of the parking lots. If canopy solar over the parking spaces is an option that the site would consider, there is an added benefit of shaded parking for the City vehicles and employee cars. Solar performance impacts from nearby trees will need to be taken into account if considering the canopy solar, but at an estimated install price of $1.25/watt, the economics may be suitable for at least a portion of the desired solar to be a parking lot canopy installation.

The facility has received vendor quotes for the installation of roughly 100 kW-DC of roof mounted solar, following a fitment of solar to almost all available roof space. As a 100-kW solar array needs about 7,000 square feet of available ground or roof space, the facility is well suited for at least the amount of solar included in the resiliency scenario. To accommodate for the natural daylight from the solar tubes and skylights, any rooftop solar system should be designed to avoid shading these features as much as possible.



2 Resiliency Solution

TARGETED OUTAGE

2.1.1 36-Hour

The GDS team developed a solar and battery dispatch model that utilizes the facility load profile, estimated solar performance, and battery performance of a standard efficiency lithium-ion battery, in a resiliency only mode, sized to meet the peak demands of the critical load. Our team looked at a 36-hour power outage scenario with 50% of the normal load surviving, considered the critical load. The GDS tool provides useful performance data of typical installations and allows for economic adjustments to suit the individual characteristics of the facility and resiliency scenarios. The 100 kw Kohler generator is not assumed to be running in our analysis. For the Public Works building, the team chose to model an outage occurring in the middle of August in order to capture increased run time of HVAC equipment that would otherwise be offset by human and equipment heat load in the winter. The event began at 7:00 am in the middle of August, utilizing weather data and load shape information based on the year 2019.

LOAD PROFILE

To provide the best fit model results, GDS chose to build an hourly load shape for the facility based on available monthly utility billing data, extrapolated to hourly impacts and has provided a typical load profile in the graph below for reference. As the focus here is on a reduced load profile during a grid disconnected outage, the load shape is only used to inform the behavior outside of the event analysis for comparison purposes. As you can see, the normal facility load has a constant minimum load overnight and it is recommended to identify that load.

SOLAR

Although there will be price fluctuations between roof-mount, ground-mount, or solar canopy installations on a cost per watt basis, these differences should be nominal but dependent on associated infrastructure costs that should come from the proposing solar vendor. For this facility, a conservative 78 kW solar PV system would have sufficient capacity for the projected outage and is a major factor in the sizing of the battery system, as it reduces the needed battery capacity. Reducing the size of the solar project would cause the battery system to increase in estimated kWh and kW capacity, with the converse being true to a point. As this is a resiliency model project, an assumption was made that adverse weather or significant cloud cover have been reduced or subsided at the beginning of the critical outage and solar irradiance is at normal conditions.



BATTERY

For the event duration analyzed, the GDS analysts assumed a lithium-ion installation that minimizes the life cycle cost of energy at the site. The battery power (kW) and capacity (kWh) are independently optimized for resiliency, this optimized size is not guaranteed to be commercially available. Further, there are many configurations of battery systems, such as the Sonnen Eco that internally incorporates inverters and transfer switches in order to reduce external infrastructure requirements. It is not the intention of this report to provide detailed design documents, but rather advise on the facility’s critical event battery capacity scenarios. Considering a 36-hour resiliency outage at Public Works, the nominal battery performance specs are 35 kW and 277 kWh, for power and capacity respectively. Included in section of 4 of this report is a sample of available battery technologies and features.

2.4.1 36-Hour Event

As previously mentioned, the battery needed for a 50% critical load, 36-hour outage event has an ideal nominal capacity of 277 kWh and a power capacity of 35 kW. The battery will dispatch power to serve the critical load in a behavior pattern similar to the chart below, for the projected outage.



PERFORMANCE MODEL

The 36-Hour Resiliency Dispatch Model is provided below for reference:

A detailed hourly dispatch model showing the theoretical interaction of the facility load, PV, and battery system was used to develop the graphs above and can be shared upon request.



3 Project Economics

ECONOMIC MODEL

The overall economics for the resiliency scenario of 36 outage incorporate certain non-energy (non-quantifiable) benefits to the City and the citizens in a critical event, being able to have continuous security at the facility, lighting, IT equipment power, and refrigeration, are all part of continuing the role of the Public Works building in ensuring public safety. These benefits, often called Avoided Outage Costs, are aggregated into a single benefit dollar amount per kWh that the user places on the unmet site load during grid outages, or the losses that the site would experience if the load were not met. The value of lost load (VoLL) is used to determine the avoided outage costs by multiplying VoLL ($/kWh) with the average number of hours that the critical load can be met by the energy system and multiplying that by the mean critical load. The costs to build in a system to survive a once per equipment lifetime event will likely always outweigh financial energy benefits of avoided energy purchases on an economic, pro-forma basis. Thus, the cost-benefit results of a resiliency only scenario should be viewed as a long-term investment rather than a short-term, net-profit investment. These costs for the 36-hour system are presented in section 2.4.2. While the focus of this scoping exercise is on the resiliency aspect of battery storage, being able to survive a planned outage, it is common for facilities to utilize storage to reduce the peak demand of the facility. Many of the major equipment manufacturers allow for intelligent utility rate integration into the battery control software or inverters, allowing for a semi-autonomous approach to battery utilization for peak shaving. For the most effective utilization of this feature, it is recommended that the facility perform an analysis of peak demand rate impacts in the existing and possible scenarios, assuming a battery installation with appropriate capabilities. Should the facility become active in something like time of use electric rates, the potential benefits of solar utilization would align well with reducing peak capacity costs or implementing a new electric rate designed to reward active monitoring of consumption patterns.

SOLAR ECONOMICS

As previously mentioned, our analysts developed a solar capacity that is a function of the battery installation and requirements to keep that system charged and above 10% for the duration of the outage. The solar sizing does not take into account the potential to sell back to the electricity provider under a net metering tariff. That said, the benefits to a solar installation of the size estimated for this facility, or larger, can include providing facility power under normal operation, as well as net metering benefits (solar power sales) to Georgia Power, scenarios

that are outside of the scope of this resiliency project. For information only, our team utilizes industry standard pricing for commercial rooftop solar that can range from approximately $1.50/watt to $3.00/watt on average, so we would expect the 78-kW system cost to range from $115,000 to $135,000. Should the facility engage multiple mounting options, these costs will vary. In the graph to the left, we have provided a modeled output of the 78 kW PV system as outputted by PVWatts. The production shown is an aggregate of solar produced, whether it was utilized by the battery to charge, internal load servicing, or sold back to the grid.


prepared by GDS ASSOC IATES INC 1 0

BATTERY ECONOMICS

The estimated cost of the 36-Hour battery solution is based on industry trends and nominal rules of thumb for larger scale storage. The associated infrastructure costs are defined as costs outside of the battery components and required material to connect the battery to an existing distribution panel, sometimes referred to as Balance of System or BOS costs. These infrastructure components, required to isolate the system as an island in an event, are commonly estimated at 30% and will be subject to the detailed design phase at the onset of the project. Further examination by electrical trades should be utilized to advise on infrastructure costs, i.e. integrating with the existing transfer switch and subpanels, etc. The turnkey installation costs for the battery system alone (system and connection to load center only) are estimated between $265,000 and $285,000.



4 Project Recommendations

PROJECT OPTIONS

GDS has reviewed the facility goals and projected project economics at a conceptual level and recommends that either project design would be suitable to move forward with a detailed design phase. At this point, more accurate auditing and scoping would take place. Below, we have provided some available commercial battery storage options and features to help facilitate a future discussion between facility personnel and available vendors.

4.1.1 Commercial Scale Energy Storage Energy storage building blocks are being offered by several vendors for deployment in commercial scale

applications. Lithium-ion batteries are evolving and there is an increase in Lithium Ferrous Phosphate (LFP) technologies

being designated for projects due to higher stability and reduced dependency on cobalt. Tesla Power Pod is an example of a product that can incrementally add up to 232 KWH of capability with lower

capacity configurations available. Samsung, Schneider, Sonnen, LG Chem, BYD and several other vendors have competitive products. 10-Year warranties and service agreements available. Installed cost currently estimated at $1,000/kwh for commercial scale systems.

Decatur Public Works

Building

Resiliency Feasibility Study

March 10, 2021

GEFA GEORGIA ENVIRONMENTAL FINANCE AUTHORITY

P R E P A R E D B Y G D S A S S O C I A T E S , I N C .

to: andrea arnold, city manager cc: from: date

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