How many solar panels do I need for a 2,000 sq ft house?

A 2,000 sq ft home uses roughly 1,000 kWh per month and typically needs about 24 panels (a ~9.7 kW system) to fully offset usage. But square footage is only a rough proxy — your actual electricity bill is far more accurate, because two same-size homes can use very different amounts of power.

How many panels do I need for a 1,500 sq ft house?

A 1,500 sq ft home averages around 750 kWh per month and usually needs about 18 panels (a ~7 kW system). Heating type, climate, and EV charging shift this significantly — size from your bill, not just your floor area.

How much roof space do I need for solar panels?

Plan for about 17.5 sq ft per panel including spacing. A typical 20-panel system needs roughly 350 sq ft of unshaded roof. South-facing roof planes with minimal obstructions are ideal.

Should I oversize my solar system?

If you plan to add an EV, a heat pump, or otherwise electrify, size 30–50% above your current usage. Panels are the cheapest part of the system to add up front, and net metering rules in many states make a slightly larger array worthwhile.

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Solar Panel Calculator: How Many Panels Do You Actually Need?

Enter your monthly electricity usage and your state. We compute the exact number of 400W panels required to offset your usage, the system size in kilowatts, and the roof area you need to fit them.

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Monthly kWh Usage

State

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Panels Needed

System Size

6.8 kW

Roof Space

315 sq ft

How Panel Count Is Calculated

Panel count starts from your monthly electricity usage in kilowatt-hours. We divide by 30 to get a daily usage figure, then divide that by your state's peak sun hours per day adjusted by an industry-standard 80% derate factor (which accounts for inverter losses, soiling, wiring losses, and temperature derate).

That gives the kilowatt rating your system needs. Dividing by 0.4 kW (the wattage of a typical residential panel in 2026) gives the panel count, rounded up. Roof space requirement assumes 17.5 sq ft per panel including spacing.

Real systems are often slightly oversized to account for future EV charging, heat pump conversion, or general electrification. If you're planning to electrify, model 30-50% above current kWh usage.

Typical Panel Counts by Bill Size

$100/mo bill

panels (typical)

$150/mo bill

panels (typical)

$200/mo bill

panels (typical)

$300/mo bill

panels (typical)

How Many Panels by House Size

Square footage is a rough starting point — your actual electricity bill is far more accurate. These estimates assume roughly 0.5 kWh per square foot per month and 4.5 peak sun hours.

Home Size	Est. Monthly kWh	System Size	Panels Needed
1,000 sq ft	500 kWh	4.6 kW	12
1,500 sq ft	750 kWh	6.9 kW	18
2,000 sq ft	1000 kWh	9.3 kW	24
2,500 sq ft	1250 kWh	11.6 kW	29
3,000 sq ft	1500 kWh	13.9 kW	35

Solar Panel Calculator FAQ

Most US homes need 15 to 26 panels (a 6–10 kW system). The exact count depends on your monthly electricity usage and your local sun hours. Divide your monthly kWh by 30 for daily usage, divide that by your peak sun hours times an 80% derate factor to get system size in kW, then divide by 0.4 kW per panel. Or just use the calculator above.

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Now see what those panels save you

Panel count is step one. Run the full savings calculator to see net cost after the 30% federal credit, payback period, and 25-year savings for your state.

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Savings

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