[Editor's note: This article was updated on December 6, 2018 to reflect formal approval of the policy by the California Building Standards Commission.]
As you may have heard, California recently became the first state to mandate solar PV systems on all new homes. This is a momentous decision for the industry; it brings the benefits of solar, a historically niche product, directly to a significant portion of homeowners. The policy will dramatically expand the size of California’s solar market–already the most mature in the nation–and perhaps it will eventually inspire similar action in other states.For California solar companies that position themselves effectively, this could open up some great opportunities to serve a vast new sector. In today’s article, we detail what’s required under the new policy so you can make sense of what’s changing and assess the market opportunities.
What policy establishes California’s new home solar mandate?
On May 9, 2018, the California Energy Commission (CEC) approved the 2019 Building Energy Efficiency Standards. What’s significant in this update to the Building Code is that, starting in 2020, every new home built in California will be required to have a PV system installed. (That is unless the building qualifies for an exception, of which there are a few). The policy got official approval from the California Building Standards Commission in December 2018.
What types of buildings are covered under California’s solar mandate for new homes?
The code states that the solar requirement applies to “all low-rise residential occupancies including single-family homes, duplexes, garden apartments, and other housing types with three or fewer habitable stories.” This includes multi-family housing like apartment buildings as long as they are under three stories. And for single-family homes, it doesn’t matter how tall the building is–all homes of that type must comply.
California’s mandate of solar on new home requires solar PV systems be installed on all new homes, including both single-family and low-rise multi-family homes.
There are a few exceptions under which a home would not be required to have a PV system (such as including when there is limited unshaded roof space) or would be allowed to install a smaller system. Multistory buildings with limited roof space and homes that incorporate energy storage can qualify for a smaller PV system. Additionally, buildings that are permitted prior to January 1, 2020 will be exempted from the requirement.
What is required to comply?
One of the most important things to understand is the required size of the PV system under California’s solar mandate for new homes. The policy establishes a minimum PV system size for a home based on the building’s projected annual electrical usage.
Minimum PV system size is calculated based on the conditioned floor space (square feet) and the climate zone where the building is located. (To determine what zone your building is located in, you can use the EZ Building Climate Zone Search App developed by the CEC.) In order for a home to receive a building permit, the builder will need to demonstrate that it will have a solar system of at least that size.
A map of California’s Building Climate Zones; the zone a new home will be built in will influence the size of solar PV system that must be installed under the state’s new mandate of solar on all new homes. To determine what zone your building is located in, the EZ Building Climate Zone Search App is a handy tool. (Image credit: CEC)
Aside from requiring compliance with the minimum system size, the policy allows some freedom for solar contractors and builders to meet the requirements in different ways. For one, developers could choose to install a community solar installation for a group of homes instead of putting rooftop solar on each building. However, they would need to be able to demonstrate that it would offer equivalent benefit to residents as if they had solar on their own home.
Additionally, a variety of solar financing options are allowed. Systems could be owned by the homeowner (added into the cost of the home) or third-party owned. This means depending on what kinds of solar financing your solar company offers customers, you’ll have flexibility.
How do you determine the required PV system size?
The code includes two different paths for compliance, prescriptive and performance; either can be used to meet California’s solar mandate for new homes. The prescriptive approach utilizes a formula to specify the minimum PV system size (see the appendix at the end of this article for the formula and an explanation). This method is simpler but less flexible.
The performance method (aka “computer compliance method”) is a little more complex but allows for greater flexibility. The CEC has created a free software program (“CBEC-Res”) to allow contractors to model alternative PV sizes, based on different building characteristics like battery storage or demand response.
Some details of the policy, including more specific guidance for compliance, are still being developed by the CEC. We’ll continue to share relevant updates as they are available. In the meantime, you can check out the resources below to learn more.
Finally, if you want to prepare your company to take advantage of the resulting business opportunities, check out Aurora’s recent webinar hosted by Solar Power World.
An example of a solar project site model created from building roof plans in Aurora–one of the ways Aurora makes it easy to adapt your solar design processes for this new solar market. Our webinar (linked above) demonstrates this process.
- 2019 Revised Energy Code (the actual code language)
- 2019 Draft Compliance Manuals–Residential Manual
- Joint Appendix 11 of the 2019 code covers PV system standards.
- Joint Appendix 12 of the 2019 code covers solar + storage scenarios.
- EZ Building Climate Zone Search App–This tool helps you determine what climate zone a California house is located in (which impacts the size of the solar installation required).
- EnergyCodeAce–This site offers free trainings on energy code issues, as well as other resources.
- Courses for the 2019 code are not yet available but should be forthcoming.
- CBECC-Res Compliance Software–This is the free software CEC developed to help builders and installers determine required system size based on building characteristics.
- CEC Energy Standards Hotline
- You can call this hotline for answers to code-related questions on weekdays from 8 a.m. – noon and 1 p.m. – 4:30 p.m.
- (800) 772-3300
- (916) 654-5106
- CEC’s Blueprint Newsletter–A periodic newsletter with advice on code compliance.
- The April - September 2018 issue has insights related to the 2019 building code.
The following formula establishes the minimum PV system size for a new building under the prescriptive approach in the 2019 Building Energy Efficiency Standards. For a full explanation, see section 7.2 of the 2019 (Draft) Residential Compliance Manual (a final version is still under development at the time of writing so this draft version is the latest guidance).
kW PV required = (CFA x A)/1000 +(NDwell x B)
Here’s what those variables mean:
- kWPV = kWdc size of the PV system
- CFA = Conditioned floor area
- NDwell= Number of dwelling units
- A = Adjustment factor from Table 7-1 (see below, center column)
- B = Dwelling adjustment factor from Table 7-1 (see below, right column)