How many solar panels do I need for 1,500 kWh a month?

Data checked October 2026

Short answer

To cover 1,500 kWh a month (18,000 kWh a year) at a typical U.S. location (median state, 1,340 kWh per kW a year), you need about 13.6 kW — 31 × 440-W panels on roughly 834 sq ft of roof.

Math: 18,000 kWh ÷ 1,340 kWh per kW = 13.43 kW, rounded up to 31 whole 440-W panels (13.64 kW).
Production: about 18,278 kWh a year, 1,523 a month on average — more in summer, less in winter.
Panel size matters: 34 × 400-W or 30 × 460-W panels do the same job.
Typical price: about $35,055 at the $2.57/W national median, with no federal credit for a 2026 purchase.
1,500 kWh a month usually means a large home, electric heat, a pool pump or an EV on top of normal use.

Adjust it to your exact job

Your electricity use

I know my

Electricity use

kWh/mo

Use a 12-month average from your bill. U.S. homes averaged 874 kWh a month in 2025 (EIA).

Where and how

State

median state: 4.93 peak sun hours, 1,340 kWh per kW per year after 14% losses.

Panel wattage

Offset target

% of use

100% is typical where exports earn the retail rate.

You need about

13.6kW DC

31 × 440-W panels · 834 sq ft of usable roof · 18,278 kWh a year (102% of your use)

Production per year: 18,278kWha typical U.S. location, 20° south roof
Per month (average): 1,523kWhvs. 1,500 kWh used
Peak sun hours: 4.93h/dayPVGIS estimate
One panel makes: 1.62kWh/day590 kWh/yr
Panel area: 667sq ftmodules only
Typical price: $35,055at $2.57/W, before incentives

Same target, other panel sizes

Panels needed by wattage
Panel	Panels	System	Roof area
400 W	34	13.6 kW	832 sq ft
420 W	32	13.44 kW	822 sq ft
440 W	31	13.64 kW	834 sq ft
460 W	30	13.8 kW	844 sq ft

Export rules: 1:1 net metering

Varies by state and utility. The national default assumes 1:1 net metering, the best case — pick your state for its actual export rules.

What it pays back

The price of this system, the 2026 tax situation (the 30% federal credit ended for homeowner purchases completed after 2025) and your break-even year are in the solar payback calculator.

Shopping list

31 panels 440-W solar panels13.64 kW DC array
834 sq ft Usable roof area (incl. setbacks)

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Compare

1,500 kWh a month in different states (440-W panels, 100% offset)

State	kWh per kW	System kW	Panels	Roof sq ft
Arizona	1,755	10.6	24	646
California	1,677	11	25	673
Texas	1,421	12.8	29	780
Florida	1,455	12.8	29	780
North Carolina	1,446	12.8	29	780
New York	1,291	14.1	32	861
Massachusetts	1,302	14.1	32	861
Illinois	1,265	14.5	33	888
Washington	1,077	16.7	38	1,023

How this was worked out

Location changes the answer by about 58%: the same 1,500 kWh takes 24 panels in Arizona but 38 in Washington. At 13.6 kW this is bigger than the 12 kW median system quoted on EnergySage in 2026.

Sun-hours check: 1,500 kWh a month is 49.3 kWh a day. With 4.93 peak sun hours and the 0.74 derate factor implied by the modeled yield (losses, inverter, heat), 49.3 ÷ (4.93 × 0.74) = 13.43 kW — the same answer.

Where exports earn less than retail (California, Arizona, Utah, Georgia and others), many installers size to about 70% of use: 9.7 kW here. Run the numbers in the solar payback calculator.

The full method, material data and tips are on the main solar panel calculator page.

Similar jobs

Other sizes people check

Sources

Data behind this answer

NLR (formerly NREL) PVWatts v8 — 14% losses, 20° tilt, south; kWh per kW DC by state city · checked October 2026
EU JRC PVGIS v5.3 (ERA5) — Fallback yields for states PVWatts was not fetched for (low confidence) · checked October 2026
EnergySage — best solar panels ranking — Top residential panels 430–460 W, 22–23% efficient · checked October 2026
Berkeley Lab — U.S. Distributed Solar and Storage Data, 2026 update — $3.6/W host-owned median; 7.7 kW median; roof coverage 22–31% · checked October 2026
EIA-861 2025 (average monthly bill and use) — U.S. average 874 kWh/month; state averages · checked October 2026
EIA Electric Power Monthly, Table 5.6.B — Residential price by state, Jan–Aug 2026 · checked October 2026
EnergySage H1 2026 marketplace report (via Mercom) — $2.57/W median; batteries $1,130/kWh · checked October 2026
EnergySage — solar rebates and incentives by state — State credits, rebates and export rules · checked October 2026
NLR PV Fleet Performance study (OSTI 1864619) — Degradation 0.5%/yr default; 0.88%/yr hot climates · checked October 2026

Short answer

To cover 1,500 kWh a month (18,000 kWh a year) at a typical U.S. location (median state, 1,340 kWh per kW a year), you need about 13.6 kW — 31 × 440-W panels on roughly 834 sq ft of roof.

Math: 18,000 kWh ÷ 1,340 kWh per kW = 13.43 kW, rounded up to 31 whole 440-W panels (13.64 kW).

Production: about 18,278 kWh a year, 1,523 a month on average — more in summer, less in winter.

Panel size matters: 34 × 400-W or 30 × 460-W panels do the same job.

Typical price: about $35,055 at the $2.57/W national median, with no federal credit for a 2026 purchase.

1,500 kWh a month usually means a large home, electric heat, a pool pump or an EV on top of normal use.

Adjust it to your exact job

Your electricity use

I know my

Electricity use

kWh/mo

Use a 12-month average from your bill. U.S. homes averaged 874 kWh a month in 2025 (EIA).

Where and how

State

median state: 4.93 peak sun hours, 1,340 kWh per kW per year after 14% losses.

Panel wattage

Offset target

% of use

100% is typical where exports earn the retail rate.

You need about

13.6kW DC

31 × 440-W panels · 834 sq ft of usable roof · 18,278 kWh a year (102% of your use)

Production per year: 18,278kWha typical U.S. location, 20° south roof
Per month (average): 1,523kWhvs. 1,500 kWh used
Peak sun hours: 4.93h/dayPVGIS estimate
One panel makes: 1.62kWh/day590 kWh/yr
Panel area: 667sq ftmodules only
Typical price: $35,055at $2.57/W, before incentives

Same target, other panel sizes

Panels needed by wattage
Panel	Panels	System	Roof area
400 W	34	13.6 kW	832 sq ft
420 W	32	13.44 kW	822 sq ft
440 W	31	13.64 kW	834 sq ft
460 W	30	13.8 kW	844 sq ft

Export rules: 1:1 net metering

Varies by state and utility. The national default assumes 1:1 net metering, the best case — pick your state for its actual export rules.

What it pays back

The price of this system, the 2026 tax situation (the 30% federal credit ended for homeowner purchases completed after 2025) and your break-even year are in the solar payback calculator.

Shopping list

31 panels 440-W solar panels13.64 kW DC array
834 sq ft Usable roof area (incl. setbacks)

State

kWh per kW

System kW

Panels

Roof sq ft

Arizona

1,755

10.6

646

California

1,677

673

Texas

1,421

12.8

780

Florida

1,455

12.8

780

North Carolina

1,446

12.8

780

New York

1,291

14.1

861

Massachusetts

1,302

14.1

861

Illinois

1,265

14.5

888

Washington

1,077

16.7

1,023

How this was worked out

Location changes the answer by about 58%: the same 1,500 kWh takes 24 panels in Arizona but 38 in Washington. At 13.6 kW this is bigger than the 12 kW median system quoted on EnergySage in 2026.

Where exports earn less than retail (California, Arizona, Utah, Georgia and others), many installers size to about 70% of use: 9.7 kW here. Run the numbers in the solar payback calculator.

The full method, material data and tips are on the main solar panel calculator page.