The 2022 Building Energy Efficiency Standards (Energy Code) has solar photovoltaic (solar PV) system requirements for all newly constructed low-rise multifamily buildings (buildings that have up to three habitable stories).

Multifamily buildings are defined as having the following occupancy groups:

  • R-2, other than a hotel/motel or timeshare property
  • R-3 that is a nontransient congregate residence other than
    • Boarding houses greater than six guests
    • Alcohol or drug abuse recovery homes of more than 6 guests
  • R-4

These requirements do not apply to additions or alterations to existing or unconditioned low-rise multifamily buildings

The installed solar PV system is intended to offset the electrical consumption of the proposed building, as if it were a mixed fuel building (assumes a natural gas furnace, water heater, stove, and clothes dryer). This means electric heat pump space heating and water heating loads, and electric appliances will not affect the minimum solar PV system size requirement. The climate zone, conditioned floor area, and possible plug loads of a building will affect its cooling demand and therefore its required solar PV system size.

Prescriptive Compliance
Section 170.2(f)  has two methods to determine the minimum solar PV system size; the required size will be the smaller of the two methods.

  1. Maximum solar PV system that can be installed on the building’s Solar Access Roof Area (SARA)
  2. A calculation (Equation 170.2-C), based on three factors:
  • Conditioned floor area
  • Number of dwelling units  
  • Climate zone of the building

The Solar Access Roof Area (SARA) is the area of all roofs of a building, covered parking, carports, and all newly constructed structures on the property, capable of supporting a solar PV system per Title 24, Part 2, Section 1511.9. SARA excludes roof areas:

  • With < 70 percent of annual solar access, accounting for shading obstructions
    • For steep sloped roofs, only existing permanent obstructions (e.g., trees, hills, nearby structures)
    • For low sloped roofs, all obstructions including external obstructions and those that are part of the building design and elevation
  • Occupied as specified by California Building Code Section 503.1.4
  • Unavailable due to compliance with other code requirements, if confirmed by the California Energy Commission Executive Director

Performance Compliance
The minimum solar PV system size requirement will be based largely on the factors described above. Additionally, increasing the building’s energy efficiency (e.g., installing more efficient space cooling, increased insulation) will decrease its electrical consumption and decrease the required solar PV system size. However, installing a larger solar PV system in exchange for less energy efficiency is not allowed. A battery storage system is not required for low-rise multifamily buildings, but it may be modeled as compliance credit under the performance approach.

Yes. There are five exceptions that exclude low-rise multifamily buildings from the solar PV requirements, or reduce the required solar PV size:

  1. SARA < 80 contiguous square feet; for steep-sloped roofs, SARA excludes roof areas lying between 300 and 90 degrees of true north
  2. Minimum solar PV system size < 1.8 kWdc
  3. The enforcement Authority determines the solar PV system cannot meet the American Society of Civil Engineers Standard 7-16, Chapter 7, Snow Loads requirements
  4. Buildings approved by the local planning department prior to January 1, 2020, with mandatory conditions of approval
  5. If installed in conjunction with a battery storage system, the solar PV size per Equation 170.2-C may be reduced by 25 percent. The battery storage system must meet Reference Joint Appendix JA12 requirements, and have a minimum usable capacity of 7.5 kWh

No. Solar PV systems can be installed on the building’s SARA, ground-mounted on the property, or mounted atop a carport installed on the lot. Note: an alternative to installing solar PV on-site is to comply with community solar requirements using the performance compliance approach if the CEC has approved a community solar program for the building type in the area where the building is located.

The solar-ready requirements are mandatory, but only apply to:

  • Newly constructed low-rise multifamily buildings without a solar PV system shall comply with Section 110.10(b)-(d)
  • Additions where the total roof area is increased by at least 2,000 ft2

For information on high-rise multifamily buildings, see the 2022 High-rise Multifamily Solar PV Fact Sheet.

See the Blueprint for more information, including articles and frequently asked solar PV questions, about the 2022 Energy Code.


Building Energy Efficiency Standards - Title 24
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