Question 1

Do I need one Powerwall or two for whole-home backup?

Accepted Answer

A single Tesla Powerwall 3 provides 13.5 kWh — enough to run essentials (fridge, lights, WiFi, a few outlets, and a gas furnace blower) for about 12-18 hours. For whole-home backup including central AC, you'll typically want two Powerwalls (27 kWh) or equivalent. A 4-ton central AC alone draws 4-5 kW and would drain a single Powerwall in under 3 hours. Our calculator asks for your specific appliances and runtime so you don't guess wrong — overbuying costs thousands; underbuying leaves you dark when it matters.

Question 2

How does the 30% federal tax credit work for battery storage?

Accepted Answer

Standalone battery storage (3 kWh capacity minimum) qualifies for the 30% federal Investment Tax Credit under the Inflation Reduction Act, with or without solar panels. The credit applies through 2032, steps down to 26% in 2033, 22% in 2034, and expires for residential in 2035. There's no cap on the credit amount. Example: a $15,000 battery system gets you a $4,500 credit against your federal tax liability. If you can't use the full credit in one year, you can carry it forward. It's a dollar-for-dollar reduction, not a deduction.

Question 3

California NEM 3.0 — is a battery basically mandatory now?

Accepted Answer

Under NEM 3.0 (effective April 2023), California's three major utilities credit solar exports at roughly $0.04-0.08/kWh (the avoided cost rate), while import rates are $0.30-0.50+/kWh. Without a battery, you export at cheap rates and buy back at expensive rates — solar-only payback stretches to 9-12 years. With a battery, you store your excess and use it when rates are high, recovering payback to 5-7 years. A battery is no longer optional in California — it's the difference between a good solar investment and a mediocre one.

Question 4

Which states have the best battery rebates beyond the federal ITC?

Accepted Answer

California's SGIP (Self-Generation Incentive Program) offers $150-1,000/kWh depending on equity criteria and fire-risk zone. Massachusetts ConnectedSolutions pays $200-400/kWh for allowing your utility to draw from your battery during peak events (4-8 times/year). New York's NY-Sun programme and battery storage incentive add up to $5,000. Vermont, Oregon, Hawaii, and Connecticut also have meaningful state-level incentives. Our calculator includes state-level estimates — but check your specific utility's current programme, as funding caps and waitlists change frequently.

Question 5

Grid-tied vs off-grid — can I legally disconnect from my utility in the US?

Accepted Answer

In most US jurisdictions, disconnecting from the grid is either illegal for occupied dwellings or financially impractical. Building codes typically require a grid connection for a certificate of occupancy. Instead, most homeowners install a grid-tied system with battery backup — you stay connected but can island your home during outages. An off-grid exception: remote cabins and rural properties where grid extension costs exceed $30,000-50,000. In those cases, solar + large battery bank (20-40 kWh) + backup generator is the standard setup.

US Solar Battery – Maximize Your Tax Credits

Maximize your 30% solar tax credit with the right battery system

Recommended system size

Apartment / Small Home

Standard Home

Large Home / EV

Why Americans are going solar + storage now

Things to consider

US Solar Battery FAQ