2022 High-rise Multifamily Battery Storage Systems

The 2022 Building Energy Efficiency Standards (Energy Code) has battery storage system requirements for newly constructed high-rise multifamily buildings that require a solar photovoltaic (solar PV) system (2022 High-rise Multifamily Solar PV Fact Sheet).

The solar PV requirements apply to buildings where at least 80 percent of the total floor area (conditioned or not) is made up of building types specified in Table 170.2-V, including mixed occupancy buildings. These building types include:

• Grocery
• High-rise multifamily
• Office, financial institutions, unleased tenant space
• Retail
• School
• Warehouse
• Auditorium, convention center, hotel/motel, library, medical office building/clinic, restaurant, theater

These requirements do not apply to additions and alterations.

The required battery storage system size is based on the solar PV system size determined for building types listed in Table 170.2-V, including mixed-occupancy buildings.

Prescriptive Compliance
Section 170.2(h) of the 2022 Energy Code has two equations to calculate the total battery capacity for building types listed in Table 170.2-V using the solar PV system size calculated from Equation 170.2-D.

1. Rated energy capacity (Equation 170.2-E), based on:

• Required solar PV system size
• Energy capacity factor
• Round trip efficiency of the battery system

2. Rated power capacity (Equation 170.2-F), based on:

• Required solar PV system size
• Power capacity factor

The total capacities of a battery storage system shall not be less than those calculated from the equations above. For mixed use buildings that contain the building types listed in Table 170.2-V, the capacities should be determined for each building type, including its support areas, then added together for the entire mixed use building.

Performance Compliance
The standard design battery storage system size is determined using the prescriptive solar PV size requirement for the proposed design, regardless of the fuel type. A battery storage system can be installed as a standalone system for additional compliance credit, when not required prescriptively. Also, a battery system larger than the prescriptive requirement can be used to tradeoff for a smaller solar PV system.

Yes. Two exceptions can exclude high-rise multifamily buildings from the battery storage system requirements:

1. If the installed solar PV system size is < 15 percent of the size calculated from Equation 170.2-D
2. Buildings with battery storage system requirements < 10 kWh rated capacity

NOTE: The solar PV requirements still apply when exempted from battery storage.

The installed battery must meet or exceed requirements in the 2022 Reference Joint Appendix JA12 and be manufacturer-certified to the California Energy Commission (CEC). A list of certified batteries is available on the CEC website.

The battery storage system must meet the minimum system performance requirements specified in Table 1 below, in addition to the following requirements:

• Control strategies,
• Interconnection and Net Energy Metering, and
• Verification of Certificate of Installations by the local enforcement agency

Table 1: Minimum Performance Requirements for Battery Storage Systems

Yes. The battery storage system is self-certified by the manufacturer to the CEC to meet the JA12 qualifications - PDF to comply with applicable prescriptive and performance requirements in the Energy Code. For more information, please visit the manufacturer certifications of building equipment Battery and Energy Storage Systems webpage.

Yes. The Solar Equipment Lists Program includes equipment that meets established national safety and performance standards. These lists provide information and data that support existing solar incentive programs, utility grid connection services, consumers, and state and local programs. Please note that equipment on the CEC’s Solar Equipment Lists have reportedly undergone tests to achieve minimum safety and performance standards. The CEC makes no claim or warranty on the equipment and its safety, performance, or durability. For more information, please visit the solar equipment lists webpage.

No. For compliance with the Energy Code the rated usable energy capacity of the battery storage system in kWh must be used for Equation 170.2-E - PDF. The usable capacity is the battery energy storage capacity in kWh that a manufacturer allows to be used for charging and discharging. To comply with Section 170.2(h) - PDF a battery storage system must meet the minimum qualification requirements of Reference Joint Appendix JA12 - PDF which includes having a usable capacity of at least 5 kWh and an energy capacity retention of 70 percent of nameplate capacity after 4,000 cycles covered by a warranty, or 70 percent of nameplate capacity under a 10-year warranty.

The 2022 Energy Code § 140.10 - PDF and § 170.2(g-h) - PDF have prescriptive requirements for solar PV and battery storage systems for newly constructed nonresidential and high-rise multifamily buildings, respectively. The minimum solar PV capacity (W/ft² of conditioned floor area) is determined using Equation 140.10-A - PDF or Equation170.2-D - PDF for each building type shown in Table 140.10-A - PDF or Table 170.2-U - PDF. The battery sizing is determined based on the solar PV capacity calculated for each building type. However, when the solar PV capacity is determined by multiplying the solar access roof area (SARA) by 14 watts per square foot, it yields the required solar PV capacity for the whole building. To determine the battery storage requirements, the whole building solar PV capacity needs to be allocated to each building type shown in Table 140.10-B - PDF or Table170.2-V - PDF. The CEC recommends using the percentage allocations that occur when the solar PV capacity is determined using the solar PV equation as shown in Figure 1. The CEC recommends using the SARA-based solar PV capacity percentage allocations to determine the battery capacity requirements for each building type as shown in Figure 2. The example shown in Figure 1 and Figure 2 uses a hypothetical total solar PV capacity per the equation of 699.64 kWdc and SARA-based solar PV capacity of 296.42 kWdc for a mixed-use, newly constructed building.

Figure 1: Example of Allocations for SARA-Based PV Capacity.

 

Figure 2: Example of Allocations for SARA-Based Battery Capacity.

See the Blueprint for more information, including articles and frequently asked battery storage systems questions, about the 2022 Energy Code.