Solar battery cost by size: 5, 10 or 13.5 kWh in 2026
What a 6 kW solar system costs with no battery, a 5 kWh, 10 kWh or 13.5 kWh battery, how to size storage, and why there is no federal credit in 2026.
A 6 kW rooftop solar system with a 5 kWh battery typically costs $24,500 installed. With a 10 kWh battery it is about $32,100, with 13.5 kWh about $37,300, and the same system without a battery about $17,000. Since January 2026 there is no federal tax credit to soften those numbers, so sizing the battery to what you actually need matters more than it did.
Every battery size, same solar system
The table prices one system, about 13 to 14 panels of 450 W on a pitched roof, with each battery option. Everything else stays the same: racking, a battery-ready inverter, wiring in conduit, a dedicated breaker, monitoring, safe roof access, installation and commissioning. Only the battery changes. We build the figures from the hours the work takes, multiplied by local electrical and installer rates, plus equipment, and check them against market prices and real quotes. They are before sales tax, and before utility connection fees and permits.
| Material | Typical | Usual range | Lifespan |
|---|---|---|---|
| No battery | $17,000 | $13,300 – $22,100 | – |
| 5 kWh battery | $24,500 | $19,100 – $31,900 | – |
| 10 kWh battery | $32,100 | $25,000 – $41,700 | – |
| 13.5 kWh battery | $37,300 | $29,100 – $48,500 | – |
For your own system size and local rates, use the calculator on Solar panels.
What each size is good for
- No battery. The cheapest way to cut your bill if your utility credits exported power fairly. The panels still work normally, but during a grid outage a standard grid-tied system shuts down for safety.
- 5 kWh. Enough to shift some daytime solar into the evening: lights, a refrigerator, electronics and some cooking. In an outage it keeps a few essential circuits running for a limited time.
- 10 kWh. Covers a typical evening and night for many homes with gas heat and cooking, or gives longer backup for essentials.
- 13.5 kWh. A size many whole-home battery products are built around. It suits larger or all-electric homes, time-of-use rate plans with expensive evenings, and households that want more resilience during outages.
Batteries in our figures are lithium iron phosphate (LFP), the chemistry most home batteries now use for its safety margin and long cycle life.
How to size a battery
- Look at your evening and overnight use. Your utility's interval data, or a smart meter app, shows how much you use after the sun goes down. That is the most a daily-cycling battery can usefully cover.
- Check your rate plan. On a flat rate with fair credit for exports, a battery saves little on the bill. On time-of-use rates, or where exports are credited at a low value, storing your own solar for the evening is worth more.
- Decide what backup means to you. A few circuits for the refrigerator, internet and lights need far less storage than air conditioning or an electric range. Backup for large loads also needs the right inverter and a critical-loads panel or a whole-home transfer setup, which can add cost.
- Do not oversize "just in case." A battery that never empties is capacity you paid for and do not use. Most systems allow adding a second battery later, so ask whether the model you are quoted can be expanded.
Cost per kWh of storage
To compare quotes, work out the battery's share of the price and divide by its usable capacity in kWh. Our table does that in reverse: the difference between the no-battery row and each battery row is the installed cost of that much storage on the same system. When one installer quotes several sizes, check the cost per kWh of each: the installation and wiring are largely shared, so a larger battery can work out better value per kWh, but only if you will actually use the extra capacity.
No federal credit since 2026
The federal Residential Clean Energy Credit (25D), which covered solar panels and batteries, does not apply to expenditures after December 31, 2025 (IRS). Some states run IRA home energy rebate programs (HEAR/HOMES), availability varies by state, and utilities sometimes offer battery or solar incentives, including payments for letting the utility use your battery at peak times. The DSIRE database lists state and utility incentives. Check before you sign, because some programs require pre-approval or a participating installer.
What is not in our figures
- Utility interconnection fees and permit fees
- Roof repairs under the array
- A main-panel upgrade if your panel has no room for the solar breaker
- Critical-loads subpanels or whole-home backup gateways beyond a standard install
Electrical work must be done by a licensed electrician and usually needs a local permit.
Before you sign
Ask for quotes with and without the battery, with the battery's usable capacity and warranty in writing, and what it will back up during an outage. Then run each price through our "Is my quote fair?" tool, which compares it with what homeowners in your area typically pay for the same system.