All New Single Family Residential constructions and ADUs are mandatorily required to have solar per the 2022 California Title 24 energy code, except for a few exceptions.
Note: Please note that the below are the minimum solar power requirements for Single Family Residences and ADUs per the latest California Title 24 energy code 2022. For multi-family, high rise residential and non-residential buildings, the requirements are different. And if your project falls under a previous code year (such as the 2019 or 2016 energy code) the requirements would again be different for Title 24.
Is your Home or ADU a New Construction?
Before we get into the exceptions, let’s first make sure your project IS a New construction. Because if not, you do not trigger the solar requirement per Title 24!
If you are doing an “addition” to your home (such as adding a few SF) or an “alteration” to your home (such as window replacements or kitchen remodel, etc), then your project is NOT a New construction and hence won’t trigger solar requirements. If you are building something New from the ground up, and there was nothing else that stood there previously or if you completely demolished what stood there previously. Only then the project likely qualifies as a New Construction for Title 24.
Similarly, ADUs that are garage conversions are Additions and don’t trigger solar per Title 24. Also, if the ADU is attached to the main home or to the garage, then too it qualifies as an Addition and won’t trigger solar. Here is a helpful blog post that explains when a project is considered as New construction versus when it is considered as an Addition or Alteration.
Calculating Required PV Size per the California Title 24 2022 Energy Code
The required solar size for Single Family Residence and ADU New Constructions per the 2022 Title 24 Energy Code depends on the conditioned floor area and climate zone. And if the required solar size is < 1.8 kW then we can claim an exception and won’t require solar.
The required solar size is calculated by Equation 7-1 in the 2022 Title 24 energy code, which is:
Required PV in kW = (Conditioned Floor Area x A) / 1000 + (Number of Dwelling units x B).
Here A and B are adjustment factors mentioned in the table 7- A in the code. Both of them are dependent on climate zone.
Below is a helpful calculator to help calculate the required PV size per the above Equation 7-1. Please enter the conditioned floor area (in Square Feet), zip code and number of dwelling units
In case you would like to have a detailed look at what the code says, here is the relevant subsection of the code containing the Equation 7-1 and Table 7-A mentioned above.
If any doubt which climate zone your project falls under, you can use this helpful tool. It will help you confirm the climate zone per the zip code for Title 24 calculations.
What exceptions are available in the code?
A few other Exceptions Besides the above, there are a few other exceptions that can be claimed but those are very site dependent and require additional documentation proving that the site qualifies for them. These include but are not limited to:
- insufficient solar access (such as if there are tall trees around the site that block the sun) or
- if there is high snow load or
- if the project is a fire re-build in a declared emergency area etc.
A few Caveats
- Please note that all of the above is for projects that fall under the 2022 Title 24 energy code. For the previous 2019 energy code, the 1.8 kW exception mentioned above is not available.
- Also, please note that certain counties have local reach codes that might supersede the above exceptions or might require a larger sized PV system. It’s best we address this once we start working on your Title 24 calculations.
- Please note that the above is for single family residential projects. For multi-family, high rise or non-residential projects, the PV requirements and exceptions are different.
- Here is a blog post that would help you calculate the solar requirements for Low Rise Multi-Family, Non-Residential and High Rise projects per California Title 24.
- Please note that there is a difference between solar requirement and solar ready requirement. Solar requirements supersede solar ready requirements.
