Size the home battery you actually need in kWh, estimate the installed cost under 2026 rules (no federal credit) — plus when storage is genuinely worth it.
SCReviewed by Sarah Chen, Energy AnalystUpdated October 1, 2026Sources: DSIRE, NREL, IRS
Home batteries are most valuable where outages or time-of-use rates are common. The 30% federal credit for storage ended for installs after 2025. Photo: American Public Power Association / Unsplash
Updated October 2026 — federal credits have ended. The One Big Beautiful Bill Act (signed July 4, 2025) ended the 30% federal Residential Clean Energy Credit (25D: solar, batteries, geothermal) and the Energy Efficient Home Improvement Credit (25C: air-source heat pumps, up to $2,000) for anything installed after December 31, 2025. Systems completed by Dec 31, 2025 can still be claimed on a 2025 return. Any 30% or $2,000 figure on this page applies only to those installs — our calculators now default to $0 federal credit. What is still available in 2026 →
Quick answerMost homeowners need a 10–13 kWh battery to back up essentials for a day. At ~$1,000/kWh installed, that's about $11,000, which is also the net cost for a 2026 install because the 30% federal credit ended after 2025. Whole-home backup with central AC needs 25–40 kWh.
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Size your battery
10 kWh
Fridge + lights + Wi-Fi + phones ≈ 5–8 kWh/day. Add AC/well pump for more.
1 day(s)
%
Lithium (LFP) batteries safely use ~90–100%.
$
2026 installed cost: ~$1,000/kWh (no federal credit for 2026 installs).
Recommended battery size
11.1
kWh usable capacity
Est. cost
$11,111
Net cost (2026)
$11,111
Typical product
1 unit
The 30% federal battery credit ended for installs after Dec 31, 2025. Backup value is highest where outages are common or time-of-use rates are steep.
How this calculator works
1
Set your daily backup energy
How much energy you want to keep running each day, in kWh.
2
Choose days of autonomy
How many days you want to run without grid or sun.
3
Account for depth of discharge
Lithium batteries safely use ~90% of capacity.
4
Get size and cost
We compute usable kWh and installed cost; there is no federal credit for 2026 installs.
How big a solar battery do you need?
Battery sizing starts with one question: what do you want to keep running, and for how long? Whole-home backup needs far more capacity than running just the essentials. Here's a rough guide to daily energy by goal:
Backup goal
Daily energy
Battery (1 day)
Essentials (fridge, lights, Wi-Fi, phones)
5–8 kWh
~8 kWh
Essentials + a few outlets & TV
8–12 kWh
~13 kWh
Add window AC or well pump
12–20 kWh
~20 kWh
Whole-home (incl. central AC)
25–40 kWh
27–40 kWh
Is a solar battery worth it?
A battery makes the most financial sense if you have frequent grid outages, live under steep time-of-use rates (charge cheap at night or from solar, discharge during expensive peak hours), or your utility has poor net metering so storing your own power beats exporting it. The 30% federal credit that used to knock roughly a third off the price ended for batteries installed after December 31, 2025, so in 2026 look for state or utility storage incentives instead. If your goal is purely lowest payback, panels usually beat batteries — check your system economics first with the Payback Calculator.
Questions
Frequently asked questions
How many kWh of battery do I need?
Multiply the daily energy you want to back up by the number of days of autonomy, then divide by usable depth of discharge. Backing up 10 kWh/day for one day with a 90% usable battery needs about 11 kWh. Essentials-only setups need ~8–13 kWh; whole-home backup with central AC needs 25–40 kWh.
Does a home battery qualify for the tax credit in 2026?
Not if it is installed in 2026. Battery storage of 3 kWh or larger qualified for the 30% federal Residential Clean Energy Credit, but the One Big Beautiful Bill Act ended that credit for installs after December 31, 2025. A battery completed by that date can still claim 30% on a 2025 return; one installed in 2026 costs the full price, about $11,000 for a typical unit, before any state or utility battery incentive.
Is a solar battery worth it in 2026?
It depends on your situation. Batteries are clearly worth it where outages are frequent, where time-of-use rates are steep, or where net metering is weak so self-consumption beats exporting. If your only goal is the fastest payback, panels alone usually win — a battery adds resilience and rate-arbitrage value more than pure savings.
How much does a solar battery cost?
In 2026, installed home batteries run about $1,000 per usable kWh before incentives, so a typical 10–13 kWh battery costs $10,000–$13,000. There is no 30% federal credit for batteries installed after 2025, so that is also your net cost unless your state or utility offers a storage incentive. Larger whole-home systems with multiple units cost more.
How long do solar batteries last?
Modern lithium iron phosphate (LFP) home batteries are typically warrantied for 10 years and 6,000–10,000 cycles, retaining about 70% capacity at end of warranty. With daily cycling, expect 10–15 years of useful service.
Sarah has spent 12 years modeling US residential solar economics, including 4 years contributing to NREL's Distributed Generation Market Demand model. She holds a BS in Mechanical Engineering from UC Berkeley and reviews every calculator and state guide on GreenCalcs against current IRS, DSIRE and EIA data. Read our methodology →
