California Solar Mandate: Is Solar Required on New Homes?
- Sarah Lozanova
- Jul 14
- 9 min read
Updated: Aug 5
The California solar mandate is a critical regulation shaping the future of homebuilding and solar energy in the state. As part of California’s broader clean energy goals, this solar panels California law requires that most new residential construction include a rooftop solar system. For solar installers, this means that solar is no longer a financial upgrade—it’s part of the building code.
Contractors, builders, and solar design partners must now ensure that every solar panel installation in California meets the energy output and system sizing guidelines set by the California Energy Commission (CEC). Understanding these rules is essential not only for compliance, but also for designing cost-effective systems that work well with current interconnection policies and battery storage incentives.
With over 12 years in the solar industry, GreenLancer helps contractors meet California solar mandate requirements with fast, code-compliant plan sets, engineering, and PE stamps for any solar panel installation in California.
Table of Contents
-- Preventing Future Solar Inverter Faults
-- California Solar Mandate is Fueling Demand
What Is The California Solar Mandate?
The California solar mandate is a state law that requires most new residential buildings to include rooftop solar. Adopted by the CEC in 2018, this solar panel California law took effect on January 1, 2020, and applies to all new single-family homes and multi-family dwellings up to three stories. It is part of California’s Building Energy Efficiency Standards (Title 24).
Under these California solar requirements for new homes, builders must install a solar energy system sized to offset the home’s expected annual electricity use. System sizing is based on variables like floor area, orientation, climate zone, and energy efficiency measures included in the building design. The law ensures that most new homes in California come equipped with solar from day one, making solar not just an option, but a requirement.
Does the California Solar Panel Law Require Batteries?
No, the California solar mandate does not require battery storage for new homes. However, adding a battery system, such as the Tesla Powerwall or Enphase IQ Battery, can reduce the required size of the solar array by up to 25% under the California Energy Code.
In some cases, combining storage with energy efficiency upgrades or demand response strategies can reduce system size by up to 40%. While batteries aren’t mandated, they offer more design flexibility when meeting the California solar requirements for new homes, and they can help homeowners maximize solar use and backup power reliability.
What is the California Solar Mandate for Commercial Properties?
The California solar mandate was expanded in 2023 to include certain commercial buildings and high-rise residential properties. Under the updated California solar panel law, newly constructed commercial properties such as offices, schools, warehouses, and apartment buildings over three stories are now required to include solar panel installation in California as part of code compliance.
While solar batteries are not required under the mandate, adding battery storage can reduce the required system size by up to 25%. Combining storage with energy efficiency strategies or demand-response programs can lead to even greater reductions, offering added flexibility when meeting California solar requirements for new homes and commercial buildings.
These expanded requirements are driving increased demand for both rooftop solar and storage systems across the state, creating strong growth opportunities for solar installers and companies partnering with GreenLancer for permitting and design services.
What is the Impact of the California Solar Mandate?
The California solar mandate has reshaped how solar contractors approach residential and commercial projects. This solar panels California law requires solar panel systems on most new buildings, creating steady demand for solar panel installation in California. Whether you’re a designer preparing PV plan sets or a contractor handling installs, understanding how the mandate affects system sizing, battery storage, and code compliance is essential.
California Solar Requirements for New Homes
Under the California solar requirements for new homes, most new single-family houses and low-rise multi-family dwellings (up to three stories) must include a rooftop solar system. These requirements began in 2020 and are part of the state’s energy code (Title 24). As of 2023, the mandate expanded to cover some high-rise residential buildings as well.
New homes must also be "solar-ready," with wiring that supports future battery storage and electric appliances. While solar batteries are not required, they can reduce the minimum required system size by up to 25% when paired with demand-response strategies and energy efficiency upgrades.
Homeowners may qualify for rebates through the Self-Generation Incentive Program (SGIP). The California Public Utilities Commission (CPUC) allocated over $280 million in 2025 toward residential solar and battery adoption, with extra support for low-income and fire-risk zones.
Costs and Considerations of the California Solar Panel Law for New Homes
Despite its environmental benefits, the California solar panel law has drawn criticism for increasing upfront costs. The California Energy Commission estimates that solar adds around $9,500 to the cost of a new home. That translates to an estimated $40 per month increase in mortgage payments. However, the CEC also projects homeowners will save around $80 monthly on electricity, yielding net long-term savings.
That said, the rollout of NEM 3.0 has reduced compensation for exported solar energy by about 75%, which may reduce bill savings unless systems are paired with battery storage to maximize self-consumption.
California Solar Mandate for Commercial Buildings and High-Rise Projects
California regulators have updated the Build Energy Efficiency Standard, which impacts commercial properties. Under the California Solar Mandate, numerous new commercial projects, including retailers, offices, schools, apartment complexes, and medical facilities, are required to install solar systems with battery storage.
The CEC estimates this will add 280 MW of solar energy capacity annually, which creates a lot of work for solar contractors. In addition, the mandate will also add an estimated 480 MWh of battery capacity to commercial properties.
California is promoting the installation of storage batteries partly to reduce the impacts of public safety power shutoffs where utility companies shut off the electricity to help prevent wildfires.
Tools For The California Solar Mandate in 2025
The California Energy Commission has approved using the Solar Assessment Tools to comply with the California Solar Mandate. These tools include:
The Solar Photovoltaic (PV) Calculator assesses a building's energy characteristics and estimates the number of photovoltaic modules needed.
The California Solar Shade Analysis evaluates available solar access to a development site and estimates energy savings from incorporating shading structures or vegetation.
The California Utility Allowance Calculator (CUAC) calculates utility allowances for low-income housing projects based on the design of the photovoltaic system, the proposed building's energy features, and any relevant utility rates or tariffs.
GreenLancer’s design and engineering portal: A fast way to get permit-ready plan sets and PE stamps tailored to Title 24 requirements
FAQs About the California Solar Mandate 2025
The California solar panel law has sparked many questions from homeowners, contractors, homebuyers, and solar installers. As the California Solar Mandate continues to shape the construction of new homes, it’s crucial to understand the implications for home energy design, installation processes, and compliance with the latest solar requirements.
Are There California Solar Mandate Exemptions?
Some California homes with small roofs or a lot of shading may also be exempt from installing a rooftop solar array. Also, some seasonal properties are exempt from the solar mandate. The property must lack one basic utility or amenity for year-long occupancy to qualify for an exemption. In addition, multi-unit buildings in areas without virtual net energy metering are exempt from the California Solar Mandate.
One way to satisfy the mandate requirements for new homes is for residents to subscribe to a community solar farm instead of installing rooftop solar systems.
Are Solar Panels Required For New Homes In California?
The California Energy Code requires solar panels on new homes as of 2020. The California Solar Mandate states that most new residential buildings have solar energy systems, including single-family houses and multi-family buildings up to three stories. Still, some exceptions exist for the California solar requirement for new homes for vacation properties, houses with small roofs, and shaded properties.
What is the California Solar Panel Law?
The California Solar Mandate, sometimes called the California solar panel law, requires all new residential buildings up to three stories and new commercial properties to install solar photovoltaic systems. This law aims to promote renewable energy, reduce greenhouse gas emissions, and increase energy independence by ensuring new constructions harness California's abundant solar resources.
What if a Home Doesn’t Comply with the California Solar Panel Law?
Not meeting the California Solar Mandate for new homes can result in significant delays. Homes may encounter difficulties securing building permits, and local authorities may withhold final occupancy approval until the solar energy requirements are fulfilled. Since exemptions under the California Solar Mandate apply only in specific situations, most homes will need to install solar energy systems to pass inspection and be legally habitable.
Are There Tax Benefits To The California Solar Mandate?
California solar incentives, including the federal tax credit for residential and commercial projects, can significantly reduce the total cost of a solar PV system. Commercial projects can also qualify for accelerated depreciation or bonus depreciation.
Also, per section 73 of California’s revenue and taxation code, solar systems are exempt from property taxes. This means that installing solar panels will not increase property taxes despite boosting property value.
Do Other States Have Similar Solar Panel Mandates?
As of 2025, California remains the only state with a mandate requiring solar installations on new residential buildings. In 2018, California mandated that new single-family homes and multi-family dwellings up to three stories high install solar panels.
While other states have considered similar measures, none have implemented such mandates to date. Advocacy groups like Environment America have called for similar requirements in states including Colorado, Maryland, Massachusetts, Michigan, Minnesota, Nevada, New Mexico, North Carolina, Pennsylvania, and Texas.
Do All New Homes in California Need Solar Panels?
Under the California solar requirement for new homes, most newly built homes and apartment complexes must have solar panels, as mandated by the California Solar Mandate. This policy aims to promote renewable energy use. However, there are California Solar Mandate exemptions for homes that face conditions unsuitable for solar power generation, such as excessive shading or limited roof space. These exemptions ensure that solar installations remain practical and feasible for each property.
How Many Homes in California Have Solar Panels?
California has the largest solar power capacity in the U.S., with over 51.9 GW installed. This is enough to power nearly 13.9 million homes. As of 2023, solar energy accounts for about 32% of the state’s electricity generation. The California Solar Mandate for new homes has significantly contributed to this growth, further cementing California as a leader in renewable energy.
How Does the California Solar Mandate Affect Homebuilders?
The California Solar Mandate requires homebuilders to incorporate solar panels into new residential construction, significantly impacting design and construction planning. Builders must allocate space for solar energy systems, meet specific solar-ready requirements, and ensure that the electrical infrastructure supports solar installations.
This mandate can increase upfront construction costs, but it also offers long-term benefits by boosting the energy efficiency of new homes. California homebuilders need to stay informed about the latest regulations to avoid delays in obtaining permits and ensure compliance with solar requirements.
Do Solar Panels Increase Property Taxes in California?
Section 73 of the California Revenue and Taxation Code creates a property tax exclusion that prevents the solar power system from impacting the amount charged on property taxes for properties with solar panels. Thus, the solar energy system doesn’t increase the property value used for tax purposes for residential, commercial, and industrial California solar panel systems installed between January 1, 1999, and December 31, 2026.
What are the California Solar Ready Requirements in the Solar Panel Mandate?
Under the California solar mandate, newly constructed low-rise residential buildings are subject to certain solar-ready requirements outlined in the Building Energy Efficiency Standards. One key requirement involves the solar zone minimum area, which stipulates that single-family residential buildings must have a designated area for solar installation.
The exclusion prevents the addition of a solar energy system from being assessed as new construction, thereby maintaining the property's base year value for tax purposes. This means that homeowners and property owners can install solar panels without the concern of increased property taxes due to the solar installation.
However, the exclusion is scheduled to sunset on January 1, 2027. Therefore, any active solar energy systems installed before this date will continue to benefit from the exclusion. After this date, the exclusion may no longer apply unless further legislative action is taken to extend it.
Solar Permitting in California
California leads the nation in streamlined solar panel permitting efforts, revolutionizing the approval process for PV projects. Through initiatives like the Solar Permitting Efficiency Act (AB 2188), California has standardized procedures, reduced administrative hurdles, and expedited reviews. These efforts promote the widespread adoption of solar energy and serve as a model for other states striving to accelerate renewable energy deployment.
Despite the California Solar Mandate, permitting solar projects can be challenging in California and beyond due to building and electrical code requirements. Unfortunately, many solar contractors encounter red tape when obtaining solar permits. GreenLancer was founded to accelerate the adoption of solar energy by offering solar permit services, such as PV plan sets, solar engineering stamps, and interconnection applications.
SolarAPP+
California is working to streamline the solar permitting process with Solar Automated Permit Processing or SolarAPP+. This new web-based solar permitting platform was created to streamline and automate the solar plan review and PV permitting process. It is currently up and running for single-family rooftop solar systems on existing homes in certain jurisdictions, which can help implement the California Solar Mandate.
Authorities Having Jurisdiction (AHJs) in California that have fully adopted SolarAPP+ for PV permitting include Benecia, Dublin, Menifee, Modesto, Pleasant Hill, San Luis Obispo, Sacramento County, San Marcos, San Ramon, Simi Valley, Sonoma County, and Stockton. In addition, some AHJs are piloting the use of SolarAPP+, including Alameda, El Cajon, Kern County, and Palo Alto.
California Solar Mandate is Fueling Demand
With rooftop solar now required on most new residential and commercial buildings across California, there is growing demand for experienced solar professionals. For contractors, this creates a steady pipeline of projects, but not every installer has the time or team to chase down leads.
Joining GreenLancer’s Field Service Partner network is a simple way to increase your workload without handling sales or customer outreach. We connect licensed, insured contractors with solar system repair, inspection, and upgrade jobs that are ready to go. Just accept the work that fits your schedule, complete the job, and get paid fast.
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