California Commercial Solar and Storage Law requires both solar panels and energy storage systems on all new and some retrofit commercial buildings, as the California Energy Commission (CEC) updated their 2022 Building Energy Efficiency Standards.

California’s Commercial Solar and Storage Law  took effect January 1, 2023 for the following commercial properties: grocery, high-rise multifamily, office, financial institutions, unleased tenant space, retail, school, warehouse, auditorium, convention center, hotel/motel, library, medical office, building/clinic, and theaters.

Depending on variables established in the CEC’s guidance, some developments may be exempt due to available space or other requirements.  In addition if the building permit was issued prior to January 1st, 2023 the facility is not required to install solar and storage.

How Does A Developer Know How To Size Their Solar System? 

Minimum sized systems will depend on the intended use of the building and will be sized by a Watts times Conditioned Square Footage.  Here is an example of Watts Times Conditioned Square Footage for an Office Building:

A general example of minimum wattage needed for an office building is approximately 2.6 watts per 1 square foot of conditioned space. If an office building has 200,000 square feet of conditioned space, the property would need 520,000 watts or a 520 kilowatt system to meet requirement

California Commercial Solar and Storage Law

This table is a general guidance provided by the California Energy Commission for system sizes required solar PV plus storage on new and some retrofit construction.  Regardless of minimum solar requirements BCSC LLC recommends maximizing all available roof space for solar panel installation, for economic purposes: https://www.beachcitiessolarconsulting.com/solar-panels-for-corporations/

How Does A Developer Know How To Size Their Battery System? 

The rated energy capacity and the rated power capacity shall not be less than the values determined by Equation 140.10-B and Equation 140.10-C, utilizing the table below.

Equation 140.10-B

kWh_batt = kW_PVdc × B / D^0.5

kWh_batt = rated usable energy capacity of the battery storage system in kWh

kW_PVdc = PV system capacity required

B = battery energy capacity factor specified in Table 140.10-B for the building type

D = rated single charge-discharge cycle AC to AC (round-trip) efficiency of the battery storage system

Equation 140.10-C

kW_batt = kW_PVdc × C

kW_batt = power capacity of the battery storage system in kWdc

kW_PVdc = PV system capacity required

C = battery power capacity factor specified in Table 140.10-B for the building type