california solar mandate map of california

An overview of the California solar mandate

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If one state leads the rest of the country in setting the bar for solar, it’s California: the Golden State consistently tops the Solar Energy Industries Association’s list for the best states for solar, having more than four times the installed capacity than the runner up (North Carolina). 

While California has an abundance of sunshine, that’s surprisingly not the primary reason for the prevalence of solar panel installations throughout the state. In fact, much of California’s success in solar is the result of forward-thinking policies set by the state government, from the California Solar Initiative (CSI) to its ambitious clean energy goals.

The future of solar in the Golden State is looking brighter than ever thanks to the new, first-of-its-kind California solar mandate, a recent code that requires new homes to be built with a solar electricity system. In this article, we’ll give an overview of the mandate, as well as go over some costs and savings estimates for future homebuyers in California. 

What is the California solar mandate?

The California solar mandate is a building code that requires new construction homes to have a solar photovoltaic (PV) system as an electricity source. This code, which went into effect on January 1, 2020, applies to both single-family homes and multi-family homes that are up to three stories high. 

The solar panel system needs to be large enough to meet the annual electricity usage of the building; given that electricity usage can be difficult to determine in new construction projects, builders use an estimate for each property that’s based on the building’s floor space and the climate zone in which it’s located.

However, there is flexibility when it comes to sizing the solar panel system: for one, builders can decrease the size requirement of a system on a property by incorporating battery storage into the building. In fact, you can reduce the required size of the solar panel system by as much as 25 percent when you pair it with a solar battery, such as the Tesla Powerwall or LG Chem RESU10H. Plus, by incorporating energy efficiency measures or other demand-responsive measures into building design alongside battery storage, the required PV system sizes can be downsized by 40 percent or more.

Exceptions to the California solar mandate

There are a few types of new residential construction that are exempt from the code. In some cases, properties with a small enough roof or those that receive an abundance of shade may be exempt from installing a PV system. Additionally, building developers are welcome to pursue and build community solar projects, as opposed to rooftop solar panel systems for each property, so long as they receive approval from both the California Clean Energy Commission (CEC) and the local utility company. Any community solar project offered in lieu of on-site solar needs to offer similar benefits to the new homeowner that a rooftop or ground-mounted system located on their property would provide.

California solar mandate costs and savings numbers

The California Clean Energy Commission conducted a cost-effectiveness study to determine cost and savings implications for Californians purchasing a single-family home under these new building codes. They found that, with the solar panel requirement, the cost of a newly constructed single-family home will increase by approximately $8,400, equivalent to roughly $40 extra per month in mortgage payments. (Note: they calculated this estimate using a cost assumption of $3.10 per Watt for the installed solar panel system, higher than the average cost of solar quoted for California properties on the EnergySage Marketplace.)

However, the CEC also predicts that while upfront costs of new homes will increase, the savings benefits for new homeowners far outweigh these initial costs. Assuming an average electricity rate of approximately 18 cents per kilowatt-hour (kWh), the state estimates that single-family homeowners will save about $80 a month on electricity costs. These monthly electricity bill savings, combined with paying an extra $40 each month in mortgage payments for the solar panel system, means new homeowners will come out with $40 net savings each month. Annually, this comes out to $500 per year in savings. Should electricity prices continue to rise and the cost of solar continue to fall, these savings numbers only stand to increase.

California solar mandate by the numbers

  • Additional upfront cost to new single-family homes: $8,400
  • Cost equivalent in mortgage payments: $40 per month
  • Electricity bill savings: $80 per month
  • Net savings: $40 per month, $500 per year

You can learn more about these numbers and assumptions used in calculations on the CEC’s frequently-asked-questions page.

Compare your own solar options today

Whether you’re building a home in California or another state, it’s worth exploring your solar options. If you’re interested in seeing what you can save with a solar panel system, our free-to-use Solar Calculator gives you ballpark estimates for both costs and savings with installing solar on your home or business. When you’re ready to take the next step, register for the EnergySage Solar Marketplace to receive and compare up to seven custom solar quotes online from local installers.

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About Kerry Thoubboron

Kerry has worked in solar for more than 6 years, starting her career as an Energy Advisor dedicated to helping customers compare their options and make well-informed solar decisions. She graduated from Boston University with a degree in Environmental Analysis and Policy. Outside of work, you can find Kerry snowboarding, watching The Office, or having passionate debates about which New England state is best (spoiler: it's Vermont).

32 thoughts on “An overview of the California solar mandate

  1. TK

    I noticed that any time I am near solar pannels I have horrible headaches, feel noxious and sick. I need to build an ADU on my property to house my aging mother and now due to the California mandate I’m being forced to install solar pannels on the ADU. I can’t come to terms with the fact that I am being forced to install something on my property which makes me feel sick. I understand the enviromental benefits but the pannels make me sick. How is this fair let alone consitutional? Are there any exceptions to this rule?

    1. Andrea D.

      Hi TK, so my dad is actually looking into a Pre-Manufactured ADU for his property. Doing this, he will be avoiding the solar panel requirement. Just an idea!

  2. Jackey Walsh

    I believe in solar power I always will I want my grandchildren and great-grandchildren have a good life there are many reasons why people do not have solar power if you have a manufactured home on Ste lease land you can’t have solar power friends of mine who live in California purchase solar panels and everything has been put in and permitted still they weren’t allowed to turn their solar power on this is as of one month ago I don’t understand what is going on I understand that you’re telling us that until the year 2035 the electric companies will not be online with solar power this is bull there making billions off the world they should be mandated to have solar power now

  3. Junior Navarro

    I am required to install solar panels after I close escrow on my new construction home, how long do I have from the time the house becomes mine to install the system and meet the new mandate requirements.

  4. Alan

    My home was completed mid october 2020 and it doesn’t have solar panels and the builder never mentioned Solar. It doesn’t have a hook up or anything. Is this right?

    1. Allan Timko

      You should check and see when the builder pulled permits. There was a big push at the end of 2019 to get building permits before the mandate, then builders have typ 1 year to start/finish…. OR the home/development may have met one of the exceptions. The Builders often just put in a minimum system, once you have real usage data the PV system may now be properly sized to meet your family’s needs. Hope that helps!!

  5. James Wunderlich

    Requiring solar systems on all new homes takes the cost of providing reliable power away from PG&E and puts it squarely on the backs of the homeowner. The only reason to install solar is for the long-term cost savings and the green benefit to our environment. If you don’t plan to live in your home for at least 7 years you will never recover the upfront cost. PG&E should be the utility changing over to Solar and hardening their infrastructure to survive the change in climate!

  6. Irene

    My husband and I visited a new home development in our community today at the end of our tour we were advised by the sales agent “due to the new mandate law” we have the option lease or purchase solar panels for 18,000 dollars for the model that we were interested in. I’ve never been a fan of solar panels taking over my roof plus there’s only two of us who’ll be occupying the home “Why do we need solar???

    1. Lisa

      Hi Irene – The reason for solar panels is so that the electricity consumption does not equal air pollution and Green House Gasses. While I agree with the statement that the utilities should give us energy from clean sources, PG&E is currently on track to have complete pollution free energy sources by 2035. I know that most Americans do not realize the emergency we are in with our planet and we only have about 7 years to get a grip on pollution. If we do not do this, most of the population will die prematurely and not from pleasant means. I do not want to see my grandchildren starving to death, the typical cause of death in our very near future. Other scenarios for their demise includes excessive heat exposure or accidental deaths from weather related incidents . I personally cannot handle the thought that I am responsible for the murder of the next generation, but hey, maybe you can, but I doubt it.

      1. Big Island Jim

        If your prediction of Seven years is correct then China and several other gross polluters will kill us all no matter what we do. China is using more fossil fuels at very alarming exponentially increasing levels every year. Go to Walmart etc.and try to avoid buying products made in China. China practically has cornered the market for many products in many areas. It will get a lot worse . So what do you propose to do about it? Solar power has a break even point of about eight to twenty years. What you have is an old solar power system at 8 years. And certainly an ancient power system at twenty. I live in Hawai’i. My electric bill is about $65 a month. The sacrifices one must make to live where you don’t need AC or heating. The problem is population. It’s not cow farts. It’s too many people farts. We need to slowly decrease the worlds population by half by lowering our birth rate to decrease population levels by attrition. We have far exceeded the population levels that the world can ecologically sustain. No problem if we don’t limit our population. The seven horsemen of the apocalypse will quickly take care of it the hard way.

    2. Cle Propp

      Irene, I am a realtor in AZ and whenever someone tries to sell their home with leased solar panels, the new buyer has to qualify for the additional payment of the lease and the appraiser will deduct for leased panels. I am not a fan of solar for the same reasons you mentioned. It is a wonderful thing to be green but it is also a wonderful thing to not die from heat exhaustion when their power goes out in CA and they have to borrow electricity from the surrounding states since CA does not allow nuclear power.


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