Solar energy storage: everything you need to know

Solar panels make the most power in the middle of the day, but most households use the most electricity in the evening. That mismatch is why battery storage has become a common add-on for home solar systems: it lets you save the extra power your panels make during the day and use it later, when demand (and often electricity rates) are higher.

Most home systems use lithium-ion batteries, the same type used in electric vehicles, because they're relatively affordable and compact. A battery can back up your home during a power outage, reduce how much electricity you pull from the grid at expensive times, and let you use more of your own solar power instead of selling it back cheaply. This matters most if you're on a time-of-use rate plan, where electricity costs more in the evening, or if your utility pays little for solar you send back to the grid. California homeowners under the state's newer solar billing rules (NEM 3) are a clear example: midday export rates are low and peak evening rates are high, so storing power to use later, rather than exporting it, saves more money.

Larger-scale storage options like pumped water systems or compressed air exist, but those are built for utilities, not homes. For a typical house, battery storage remains the practical option, and battery costs have been trending down as the technology matures. If you already have solar or are considering it, it's worth checking your utility's rate structure and export rules, since those determine how much a battery could actually save you.