We determine the size of a battery system by calculating the potential power and the potential energy capacity.
Station A calculates two different key numbers to determine the size of a battery system for a given building:
1. Potential Power
The power capacity of the battery storage system that could be physically installed, based on available space and the building's peak load
The physical limit represents the limit imposed by the amount of open space available to install the battery on. For each building, we calculate the area available for installing the battery indoors and out of doors.
Additional size constraints
Additionally, we set some restrictions on system sizes that can be installed indoors and outdoors, based on our customer feedback about typical permitting guidelines.
- Indoor systems ≤ 600 kWh
- Outdoor systems ≥ 300 kWh
We assume that buildings 10 stories and higher will have indoor systems, as a proxy for requiring indoor installations in dense urban areas.
We set the battery potential as the lessor of the physical limit and the energy limit. Additionally, we set a limit on system power capacity at 50% of building annual peak.
2. Potential Energy Capacity
The energy capacity of the battery storage system that could physically be installed
We currently assume all batteries have a "2-hour" duration: