Solar Panel System Sizing
Calculate how many solar panels you need to offset your electricity usage.
Your Electricity Usage
Find this on your utility bill. US average: ~900 kWh/month.
Your Solar Conditions
US regions: Southwest 6–7 · Southeast/Mountain 5–6.5 · Midwest 4–5 · Northeast 3.5–4.5 · Northwest 2.5–4
Accounts for inverter loss, wiring, temperature. Typical range: 75–85%.
Panel Specifications
— panels
Daily energy needed
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Required system size
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Actual system size (with panel count)
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Estimated annual production
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Estimated coverage
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Approximate roof space needed
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Peak Sun Hours by US Region
| Region | Hours/Day | States |
|---|---|---|
| Southwest | 6.0 – 7.0 | AZ, NV, NM, Southern CA |
| Southeast | 5.0 – 6.0 | FL, GA, TX, LA |
| Mountain | 5.0 – 6.5 | CO, UT, ID, MT |
| Pacific Coast | 4.5 – 6.0 | CA, OR, WA |
| Midwest | 4.0 – 5.0 | IL, OH, IN, MO |
| Northeast | 3.5 – 4.5 | NY, MA, CT, NJ, PA |
| Upper Midwest | 3.5 – 4.5 | MN, WI, ND |
| Northwest / Alaska | 2.5 – 4.0 | AK, northern WA, OR |