Solar Panel Calculator

How much solar you need for your power station, van, home or balcony, where you live, in the worst month as well as on average. No address, no phone number.

1

Your power station or battery

Battery size in

On the box: a station’s Wh is its battery; a panel’s W is its rated output. A 12 V 100 Ah battery is 1,200 Wh.

2

Where and how

1

What will you run each day?

2

Where, and your battery

1

Your electricity use

Enter use as

Pre-filled with your state’s 2024 average (EIA). A year of bills gives a better figure than one month; a bill in dollars includes fixed charges, so it slightly overstates your kWh.

Have a quote? Check it
1

Your kit and balcony

Solar by state

kWh a year from 1 kW of panels facing south at the best tilt (Global Solar Atlas).

How many solar panels to run…

Charging a power station or battery

System sizes

Guides

FAQ

How many solar panels do I need?

Divide the kWh you use in a year by what one kW of panels makes where you live, then by the panel size. The U.S. average home uses 863 kWh a month (EIA, 2024); in Tennessee, the middle state of the 50 and DC for sunshine, a kW of panels makes about 1,473 kWh a year, so that home needs about 7.03 kW: 18 × 400 W panels, rounded up.

Which states get the most solar output?

Per kW of panels, New Mexico (1,929 kWh a year), Nevada (1,922) and Arizona (1,907) lead; Alaska (1,080) and Washington (1,292) are lowest (Global Solar Atlas).

Is there still a 30% federal solar tax credit?

Not for systems paid for under the residential credit after 2025. The IRS says the section 25D credit “the credit will not be allowed for any expenditures made after December 31, 2025.” An expenditure counts as made when installation is completed. Our payback uses no federal credit.

Why size off-grid solar for the worst month?

Because the battery has to refill on the shortest, cloudiest days. Panels sized for the yearly average fall short every winter; the tools show both so you can choose.

Sources and assumptions

Note: These are estimates; shading, roof direction, local weather, equipment and your installer’s design change the real output. We give no wiring or installation advice: follow your equipment’s manuals, and use a licensed installer for any system connected to your home’s wiring or the grid. Net metering and export credits are not modelled. Not financial or tax advice.