The short answer
- Not required, but for most new solar homes on PG&E, SCE or SDG&E, a battery improves lifetime savings.
- It also gives you backup power during outages and shutoffs.
- It may not pay off if your evening usage is small or you're on a municipal utility with low rates.
Five years ago, we'd have called a battery optional. Under NEM 3.0, it's often the most important part of the system. Here's why, and how to tell whether it fits your home.
Why batteries matter more now
Your panels produce the most power between about 10am and 3pm. Your family uses the most between about 4pm and 9pm, which is also when time-of-use rates peak. Without a battery, the midday surplus goes to the grid for a few cents, and you buy evening power back at full price. A battery stores the surplus so you use it yourself.
Simple example: shifting 3,000 kWh a year from export (about 4¢) to evening self-use (about 35¢) is worth roughly $900 a year.
What backup power really looks like
A typical 13.5 kWh battery can run a refrigerator, lights, Wi-Fi, phones and a few outlets for about a day on its own, and much longer when the sun recharges it. It won't run central A/C all night. We'll help you choose which circuits are backed up.
What it costs
Expect about $12,000–$16,000 installed for one battery. Costs rise if your main electrical panel needs an upgrade. Because the federal 25D credit ended after 2025, homeowners buying batteries no longer get 30% back. The SGIP program still offers rebates for income-qualified households, medical-need customers and homes in high fire-threat districts.
When a battery may not be worth it
- You're on a municipal utility with simple, low rates.
- You use very little power after sunset.
- You're on legacy NEM 2.0 terms, where exports still earn near-retail credit (backup might still be worth it to you).
How to choose a battery
- Usable capacity (kWh): how much energy it stores.
- Power output (kW): how many things it can run at once.
- Warranty: look for 10 years and a stated end-of-warranty capacity, often 70%.
- Expandability: can you add a second unit later?
We quote every system both with and without storage so you can see the difference in writing. Read our battery overview or ask for a quote.
Quick questions
Can I add a battery to my existing solar system?
Usually yes, with an AC-coupled battery. We review your current equipment and interconnection terms first.
Do batteries need maintenance?
Very little. They're sealed, monitored by an app, and receive software updates automatically.