The performance approach allows for modeling of the PV system performance by taking into account the PV system size, climate, panel orientation, panel and inverter efficiency, and shading characteristics. For nonresidential and hotel/motel buildings, the standard design PV system size is determined by the smaller of the PV system size determined by Equation 9-1, or the total of all available Solar Access Roof Areas (SARAs) multiplied by 14 W/ft². The performance method allows for modeling different PV sizes, solar thermal systems, more energy efficiency measures, additional battery storage and other demand-response measures.

The allowable exceptions to the prescriptive PV requirements listed in 9.2., for nonresidential, hotel/motel and high-rise multifamily buildings or low-rise multifamily buildings, respectively, can also be used under the performance approach. The user must select the appropriate exception in the software and provide documentation to the building department with the building permit application.

The installed PV system must meet the applicable requirements specified in JA11.

Example 9-5: Efficiency Tradeoff

Question:

Does the performance path allow tradeoffs between PV systems and energy efficiency measures? How about tradeoffs between a PV system that is coupled with a battery storage system and energy efficiency measures?

Answer:

Beginning with the 2019 Standards, the performance path no longer allows installing a larger PV system in exchange for less energy efficiency measures for showing compliance with the TDV energy-based compliance metrics; however, the software will allow installing more energy efficiency, demand-responsive measures; battery and storage; and thermal storage systems in exchange for a smaller PV system. Larger PV systems can gain compliance credit for the hourly source energy-based metrics.

Example 9-6 Solar Thermal System

Question:

Does a solar thermal water heating system still qualify for compliance credit in the performance path?

Answer:

Yes, although a solar water heating system cannot serve as a substitution for the prescriptively required PV system, it can still be installed along with PV for optional compliance credit in the performance path. Solar water heating systems are modeled along with the remainder of the water heating and distribution systems and can be used for trading off efficiency measures or installing a smaller PV system. The requirements for solar thermal water heating systems are described in Chapter 4, Water Heating Requirements.