California Solar Mandate FAQs

by James Florence


The California Energy Commission’s decision to require solar on new homes has raised much inquiry regarding the mandate’s size and scope. Photo: Complete Solar Solution ©2018

On May 9, 2018, the California Energy Commission (CEC) adopted a significant update to its Title 24 Building Energy Efficiency Standards. Most noteworthy is the landmark requirement that solar photovoltaic systems be installed on all new construction homes. From the moment this groundbreaking mandate was announced, the Internet has been abuzz with commentary from both supporters and dissidents. To cut through the noise, we’ve provided some answers to frequently asked questions regarding the newly adopted mandate.

Q: When did the solar mandate take effect?

A: January 1, 2020.

Q: To which types of homes and/or buildings does the mandate apply?

A: The solar requirement will apply to new single-family homes and new multi-family housing units of three stories or less.

Q: Why did the California Energy Commission adopt the solar mandate?

A: The CEC’s decision was largely motivated by the state’s ambitious, long-term goals concerning energy efficiency. These include achieving a 50 percent rate of renewable electricity, doubling energy efficiency savings in existing residential and commercial buildings, and reducing greenhouse gas emissions by 40 percent—all by 2030. The decision also seeks to achieve California energy policy’s longstanding goal of requiring new residential construction projects to meet a zero net energy (ZNE) standard by 2020. A ZNE home produces an equivalent amount of energy to what it consumes.

Q: How much will the solar mandate add to the cost of a new home?

A: The California Energy Commission estimates that the solar requirement will add $9,500 (on average) to the cost of a new single-family home. This translates to an estimated increase of $40 per month for a 30-year mortgage. However, the actual cost of adding solar may fluctuate depending on the specific power needs of the home or housing unit.

Q: What residual cost savings is the solar mandate expected to provide for homeowners?

A: It’s estimated that homeowners’ savings on energy costs will roughly double the increase to their mortgage costs. More specifically, the CEC estimates an average monthly savings of $80 in energy bills against a projected $40-per-month mortgage increase. Long-term, the CEC estimates a total savings of $19,000 over the course of a 30-year mortgage against a $9,500 initial cost. It’s also worth noting that adding solar during home construction is far less expensive than retrofitting it to an existing home, so for homeowners who would’ve opted to install solar at some point in the future, this represents an even larger savings.

Q: What about homes situated in areas where solar is impractical?

A: The new requirement provides exceptions for homes and housing units that are situated in areas where a rooftop solar power system is deemed impractical, such as those shaded by large trees or structures. In some cases, homeowners will have the option to subscribe to a community solar installation or incorporate alternate upgrades that provide equivalent energy savings. 

Q: Will I be required to install a solar power system if I remodel my home?

A: As of now, no—the mandate only pertains to new homes and housing units. However, given California’s zeal for progress in improving energy efficiency, a solar requirement for home remodeling could very well be the next step.