Solar + Battery Storage: What to Know
What a battery does
DOE: storage lets you use solar energy "when it's needed most, regardless of whether it's sunny," including evenings "or even when the power goes out." Confirm backup capability in writing — whether a system powers your home during an outage depends on the equipment and design.
Typical sizes and costs (LBNL, Oct 2025, 2024 installs)
- Median residential battery: 13.5 kWh, most between 10–20 kWh.
- Median storage duration: about 2 hours at rated power.
- Median cash price of paired solar+storage was $1.7/W (per W of PV) higher than stand-alone solar.
- Caveat: California is ~90% of LBNL's storage sizing data.
When it may make sense
- Your utility credits exports at low rates or uses time-of-use pricing
- You want backup power for outages
- Local incentives exist (check DSIRE)
Tax credit note
Federal tax credit status: The federal residential clean energy credit (25D) doesn't apply to expenditures made after December 31, 2025, and the IRS treats an expenditure as made when installation is completed. Systems whose installation is completed in 2026 do not qualify for it. (Battery storage of at least 3 kWh had been eligible.)
Questions for your installer
- Will the battery back up the whole home or selected circuits?
- What's the usable capacity and warranty?
- How does it charge and discharge under my utility's rates?
Sources
- U.S. Department of Energy, "Homeowner's Guide to Solar" — https://www.energy.gov/eere/solar/homeowners-guide-going-solar (accessed Oct 20, 2026)
- Barbose et al., Lawrence Berkeley National Laboratory, "U.S. Distributed Solar and Storage: 2025 Data Update" (October 2025) — https://emp.lbl.gov/sites/default/files/2025-10/Distributed%20Solar%20%26%20Storage-2025%20Data%20Update.pdf (accessed Oct 20, 2026); data viewer: https://emp.lbl.gov/tracking-the-sun
- IRS, "FAQs for modification of sections 25C, 25D, 25E, 30C, 30D, 45L, 45W, and 179D under Public Law 119-21 (OBBB)" — https://www.irs.gov/newsroom/faqs-for-modification-of-sections-25c-25d-25e-30c-30d-45l-45w-and-179d-under-public-law-119-21-139-stat-72-july-4-2025-commonly-known-as-the-one-big-beautiful-bill-obbb (accessed Oct 20, 2026)
- DSIRE (N.C. Clean Energy Technology Center, NC State University) — https://www.dsireusa.org/ (accessed Oct 20, 2026)
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Last reviewed 2026-10-20.
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