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.