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2020 California Solar Requirements: Title 24 Compliance and Calculations

The new California solar requirements and energy efficiency standards of Title 24, Part 6 take effect on January 1, 2020, but you’re already preparing for these changes if you’re a home builder in the state. So what do you need to know about Title 24 compliance and calculations to stay on the right side of these new building code requirements?

Read an overview of updates made to Title 24, Part 6 and California’s solar mandate or continue reading for more in-depth details on Title 24 compliance and calculations.

What are the California solar requirements under Title 24?

The updates made to Title 24 by the California Energy Commission (CEC) require all low-rise residential buildings to have solar PV systems that meet the home’s annual electrical usage. At the same time, the CEC wanted to limit how much excess energy is fed back into the grid. To balance these needs, the following equation (found in the compliance manual on page 7-1) was developed for Title 24 to calculate the required solar panel system size:

kWpv = (CFA x A)/1000 + (NDwell x B)


  • kWpv = the size of the PV system in kilowatts (DC)
  • CFA = conditioned floor area
  • NDwell = number of dwelling units in the building
  • A and B = adjustment factors (found in Table 150.1-C of Title 24, Part 6) based on climate zones where the dwelling will be built (climate zone map in Appendix JA2)

Based on these Title 24 calculations, a 2,000 square foot home in Sacramento (California building climate zone 12) would require a 2.6 kW system while the same home in Fresno (zone 13) would require a 3.3 kW system.

Are there exceptions to the Title 24 solar requirement?

Yes! The updates to Title 24, Part 6 were written to consider the needs of the environment, customers, home builders, and utility companies and to offer as much flexibility as possible. Because of this, there are exceptions and limits to the solar requirement for new California homes.

For starters, no solar panel system is required on homes that are excessively shaded. Builders are also able to opt for additional energy efficiency, demand-responsive technology, thermal storage, and/or battery storage options to reduce the required solar panel system size. The CEC is also looking into community solar options as an alternative to home solar systems.

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