20 kWh solar battery cost

A 20 kWh solar battery costs about $22,000 installed (typically $20,000–$26,000), and backs up essential loads for about 54 hours. That's based on a modeled US-average of about $1,100 per usable kWh and ~90% usable capacity. Actual cost varies by brand, installer, and whether the battery is AC- or DC-coupled.

Typical cost
$22,000
Usable capacity
18 kWh
Essential backup
54 hrs
Whole-home backup
14 hrs

A 20 kWh battery by the numbers

Modeled US-average figures for a 20 kWh home battery at about $1,100 per usable kWh installed.

Nominal capacity20 kWh
Usable capacity (~90%)18 kWh
Typical installed cost$20,000–$26,000
Cost per usable kWh~$1,100/kWh
Essential-loads backup54 hrs (~2.3 days)
Whole-home backup14 hrs
30% credit via lease/PPA~$6,600 value
Federal credit (purchase)Ended Dec 31, 2025

Modeled national-average estimate, June 2026; varies by brand & installer — see methodology.

What can a 20 kWh battery run?

With about 18 kWh usable, a 20 kWh battery can keep essential loads — fridge, lights, WiFi, phone charging, and a few outlets — running for roughly 54 hours. Trying to run the whole home at the average US draw of about 30 kWh a day drains it much faster — around 14 hours. Backup time depends entirely on your actual loads: drop the air conditioning and electric oven during an outage and the same battery stretches a lot further. Most homeowners size storage for the essentials they want to keep on, not for the entire house.

2026 incentives on a 20 kWh battery

The 30% Residential Clean Energy Credit used to cover standalone home batteries of at least 3 kWh, but it ended for purchases placed in service after December 31, 2025 — the same cutoff as solar panels. So a 2026 cash or loan buy of a 20 kWh battery no longer subtracts a federal credit. A lease or PPA can still capture a roughly 30% credit — the provider claims it and passes the benefit on through lower payments, worth about $6,600 on a battery this size. State and utility storage rebates vary; see solar incentives by state and our are solar batteries worth it guide.

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20 kWh solar battery: FAQ

How much does a 20 kWh solar battery cost in 2026?
About $22,000 installed at a modeled US-average of $1,100 per usable kWh, with a typical range of $20,000–$26,000. Actual cost varies by brand, installer, and whether the battery is AC- or DC-coupled. The 30% federal credit on a purchase ended Dec 31, 2025; a lease or PPA can still pass through a ~30% credit worth roughly $6,600 on a battery this size.
How long will a 20 kWh battery power my home?
With about 18 kWh usable (~90% of nameplate), it runs essential loads — fridge, lights, WiFi, a few outlets — for roughly 54 hours, or an average whole home (~30 kWh/day) for about 14 hours. Real runtime depends on exactly what you keep running during an outage.
How many solar panels to recharge a 20 kWh battery?
Very roughly 11 modern 400-watt panels. A 400W panel produces about 1.6 kWh on an average day, so recharging 18 kWh of usable capacity in a single day takes around that many — more in cloudier locations, fewer in sunny ones. In practice a battery shares panels with your home loads, so most systems have plenty of capacity to top it up over a sunny day.
Does a 20 kWh battery qualify for the tax credit?
Not on a purchase. The 30% Residential Clean Energy Credit covered standalone batteries of at least 3 kWh, but it ended for purchases placed in service after December 31, 2025. A lease or PPA can still capture a roughly 30% credit (worth about $6,600 here) that the provider passes on via lower payments. Some state and utility storage rebates remain — check current rules.

Compare other sizes

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