AMBER Research

Sizing Batteries for Integration with Net-Zero Energy Residential Buildings

In this study we developed a methodology to size batteries that produces maximum net present value (NPV). This study proposes the use of two NREL energy software: BEopt and SAM. Our analysis show that for a net zero energy home with PV in Arizona is only able to mitigate 37–44% of the peak electricity purchases and 4–12% of demand charges due to mismatch between solar potential and on-peak hours. To obtain largest NPV an owner most size their batteries to about 1.5–1.6 times larger than the annual highest  purchased electric peak energy to maize operation  and maintenance cost in a 25-year period when batteries are sized to never require replacement during the PV system lifetime.

Flagstaff NPV vs. Normalized Battery Capacity. The circles indicate the number of battery replacements that are required within the 25-year system life.