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Renewable systems and energy storages for hybrid systems 161

Figure 8.3 Hybrid ESS architecture models.

participating utility was KEA of Alaska, which initiated the project to look into batteries for
providing frequency response in the system boycotting fossil fuel dependent diesel reserves.
The storage opted was an Advanced Lead-Acid battery system by Xtreme Power. The proj-
ect was implemented solely by the utility owner and was not supported by any government
funding. In the first half year of operating, the project realized in penetration of nearly 8 mil-
lion kWh of wind generated power and successfully harvested the benefits. The batteries
enabled faster responses in milliseconds and deliver rated power whenever needed.
Number of charge discharges presented over a day is as high as 250–280. But the system
required regular maintenance and temperature regulation both of which added up to the costs
incurred by the project.
2. Off-grid backup for renewable support in Angola: A 200 W/1300 kWh Lithium battery with
Solar PV for lighting a school building where the battery enabled lighting even after sun
down. Given the climatic conditions in Southern Africa, the developers opted for a Lithium
battery, which is much better adaptable and easier to maintain [19]. Regardless, the Li-ion
battery is still provided with a thermal management material. The expected DoD was 50%
for the project and the cycle life was estimated to last for >3000 cycles over a period of
6 years bringing the energy cost to less than $ 0.50 per kWh.
3. BTM with solar photovoltaics in California and Tennessee: California has an incentive pro-
gram for investments in energy storages with rates being approximately $1.62/W for invest-
ments less than 1 MW and even lesser for larger projects up to 3 MW. A case study was
conducted by NREL using System Advisor Model (SAM) tool in projects at Los Angeles
and Knoxville with Li-ion and Lead acid batteries and presented in [7]. Economic analysis