Do I Need Solar on my new ADU?

Learn when and why you need to install solar panels onto your new, California ADU. Read on for a comprehensive guide to all things solar and sustainable on your ADU.

Do I need to install solar panels for my Accessory Dwelling Unit?

Yes, California state law requires that any newly-built accessory dwelling unit must have solar panels. The California Energy Commission (CEC) states that panels can be installed on the ADU or the primary unit. Adding solar panels onto new construction is common practice for California contractors.

However, if you already have solar panels on your primary dwelling that meet the needs of your ADU, there may not be a need to add more panels onto your new ADU, per Title 24 exemptions which we will discuss later. While you definitely have the option, it is not necessary, as California only requires you to have it on one residence.

How will solar affect my ADU cost?

The cost of installing solar depends on how many kilowatts are necessary to supply your ADU with enough energy to support the amount of consumption. Solar panel design & installation on average adds around $10-15K onto the cost of your build. This is something your contractor will put into your budget during the early stages of your negotiations so you can appropriately plan.

The benefit of this requirement is that the solar panels will help reduce your energy bills and make your ADU more sustainable overall.

How will solar affect my ADU timeline?

Solar installation and permitting is carried out in parallel with the rest of the design & build process for your ADU, so no additional time will be required. The process looks very similar to the broader construction process, which includes design, permitting & installation.

All in all, this whole process will take between 60 and 90 days. The design process does not take much time, as it mainly involves determining how many panels are necessary to supply the whole ADU with energy. Obtaining solar permits, the next step, will take around 45 days depending on your jurisdiction. The solar permit is different from the general building permit, so the two will be submitted separately (all of that work is included in your proposal with Snap ADU). Typically, the solar permit will be submitted first.

The actual install of the panels comes later in the build. The roof must be completely built before the panels can be put on. This takes about 30 days, and then must be inspected to ensure quality.

How will solar affect my ADU design?

The addition of solar panels on your ADU will generally not affect the overall design of your ADU. All of our plans are designed to be solar-friendly, meaning they have a roof that will accommodate panels.

What is Title 24?

Title 24 of California state law refers to a number of regulations California has put in place to ensure energy conservation. Title 24 requires that all new construction must meet energy consumption thresholds. This often necessitates solar panels on new ADUs being constructed. As with any law there is some room for interpretation by those checking the plans. In some cases (even within the same jurisdiction) a plan checker may allow an existing solar array on the main home to count towards the ADU while another plan-checker may not. If your home as an existing solar array we will submit plans under the assumption that the existing solar array will be acceptable. Taking this approach of best case scenario does not cost us any additional time as we can amend plans based on plan check comments long before the plan check process is complete. All in all, Title 24’s requirement of reduced energy consumption necessitates solar panel installation on just about every new ADU.