Under NEM 3.0, a home battery is what makes solar pay in California. It stores daytime solar so you use it during expensive evening hours instead of exporting it cheaply, lowers your bill, and keeps essentials running during outages. Sizing depends on your evening usage and backup goals.
Battery storage used to be an optional upgrade. Under NEM 3.0, it has become the part of the system that makes solar pay. This guide explains how a home battery works, how to size one, and what it does for your bill and your resilience during outages.
How a Home Battery Works
Your panels produce the most power at midday, when grid export credits are lowest. A battery captures that production and holds it until you need it. In the evening, when utility rates peak, your home draws from the battery instead of buying expensive grid power.
The result is that you self-consume far more of your own solar. Homes with storage commonly use 80 to 90 percent of what they produce, compared with 30 to 40 percent for solar alone.
Backup Power and Outages
A battery also keeps your home running during outages and public safety power shutoffs. Essential circuits, such as your refrigerator, lights, internet and key plugs, stay powered until the grid returns. In wildfire-prone areas, that resilience is a major reason homeowners add storage.
Sizing and Rebates
The right battery size depends on how much evening and overnight usage you want to cover and whether outage backup is a priority. Your system is sized against your actual usage so it covers the hours that matter most.
California's Self-Generation Incentive Program offers battery rebates, with the largest amounts reserved for income-qualified and high-fire-risk households. Funding is limited and changes through the year, so availability is checked at the time of your assessment.
- Size to cover your evening peak and any critical backup loads.
- Check current Self-Generation Incentive Program availability.
- Most home batteries are warrantied for around ten years of daily cycling.
- Storage can often be added to an existing solar system.
| Goal | Typical approach | What it covers |
|---|---|---|
| Bill savings under NEM 3.0 | Size to evening usage | Shifts daytime solar to peak hours |
| Essential backup | One battery | Fridge, lights, internet, key outlets |
| Whole-home backup | Multiple batteries | Most or all circuits for longer outages |