900 kWh/month preset
Start with 900 kWh/month pre-filled — the same baseline used across SolarCalcNow examples.
Use this preset for the default mid-range example that makes state, rate, production, and cost differences easy to compare.
No email required
Enter monthly kWh or electric bill. The calculator uses state-level assumptions and shows the math behind the result.
Your estimate
Example resultEstimated system size: 6.8 kW. This is an estimate, not an installer quote.
Confidence
Medium
Planning estimate only — not an installer quote, engineering design, or tax advice.
Payback uses gross system cost before verified incentives, financing fees, batteries, and roof work.
Annual usage: 10,800 kWh
Annual production target: 10,800 kWh
State rate: 34.74 cents/kWh
Export assumption: Partial export credit
Direct solar use: 5,940 kWh
Modeled exports: 4,860 kWh
Panel count view
15-19 panels
Estimate shape
Privacy note: the printable report link stores estimate inputs in the URL, including ZIP and usage or bill values. Keep it private if those details are sensitive.
Local scenarios
Compare a few assumptions without creating an account.
Saved scenarios stay in this browser only and may include ZIP, bill, and usage inputs. SolarCalcNow does not sync them or send those values to analytics.
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Confidence drivers
Expected production: 10,800 kWh
System loss: 14%
Export value: Partial export credit
Direct solar use: 5,940 kWh
Modeled exports: 4,860 kWh
State production default: 1,595 kWh/kW/year
EIA Electric Power Monthly, Table 5.6.A — June 2026 - 2026-09-04
NLR PVWatts V8 · author-selected reference point - 2026-09-04
EnergySage marketplace + SolarCalcNow cost scenario - 2026-09-04
Production evidence: California has a saved full PVWatts response; eight states have successful API yields recorded to two decimals. Colorado, Illinois and Pennsylvania retain explicit author assumptions. The download distinguishes these evidence levels.
$0.3474/kWh
34.74 ¢/kWh
EIA Table 5.6.A, June 2026 residential column; published August 26, 2026. Divide the published cents/kWh by 100. This preliminary statewide average is a fallback, not your utility tariff. Use your bill's energy-only rate; fixed charges remain payable.
1,595.2 kWh/kW/year
kWh/kW/year
PVWatts V8 typical-weather model at an author-selected reference point in the state: 4 kW DC, roof mount, 20° tilt, 180° azimuth, 14% system losses. Annual AC kWh ÷ 4 gives kWh/kW/year. Losses are already included and are not deducted again. Neither a statewide average nor a ZIP or roof survey. Shade and ±10% production bounds are separate author scenarios.
$1.98–$2.98/W
$2.48/W × 0.8…1.2
EnergySage's state marketplace average, table updated August 28, 2026. We calculate an author-selected range of average × 0.8 to average × 1.2, rounded to cents/W. This ±20% scenario is not an observed price distribution or confidence interval. Cash solar only, before incentives; compare like-for-like local quotes.
SolarCalcNow provides planning estimates only. Results are not installer quotes, engineering designs, tax advice, financing recommendations, or utility interconnection approval.
Optional next step
Your estimate stays visible. This form is optional and uses explicit consent.
Installer quote matching is not active yet. You can still calculate, save, and print your estimate before contacting installers directly.
For a home using 900 kWh per month in California, the default planning estimate is a 6.8 kW system with 15-19 panels at 400 W each, producing about 10,800 kWh per year and needing roughly 411 sq ft of roof. Estimated gross cost is $13,405-$20,176 before incentives, with simple payback of 5.1 years-7.6 years. The estimate uses EIA Electric Power Monthly, Table 5.6.A — June 2026 (updated 2026-09-04) and NLR PVWatts V8 · author-selected reference point (updated 2026-09-04).
SolarCalcNow provides planning estimates only. Results are not installer quotes, engineering designs, tax advice, financing recommendations, or utility interconnection approval.
Worked scenarios, not measured households
900 kWh/month · 400 W
Author-created California scenarios using the current source snapshots, low shade and no incentives. Except for the variable shown, inputs stay fixed: 100% annual energy target, 55% direct use and export at 35% of retail. Compare your utility and roof before using the result.
| Changed input | Calculated output |
|---|---|
| 720 kWh | 5.4 kW · 14 Likely panel count |
| 900 kWh | 6.8 kW · 17 Likely panel count |
| 1,080 kWh | 8.1 kW · 21 Likely panel count |
The sizing target uses continuous DC kW; panel count rounds up. Actual module dimensions, setbacks and roof planes can change the layout. The 21 ft² per panel × 1.15 spacing model is an author assumption, not a building-code clearance.
Calculated baseline
Same inputs, different state data: 400 W panels, 900 kWh/month, low shade, 100% offset target, partial export credit, and no ZIP-level PVWatts override. This makes the state-rate and production assumptions visible before a quote.
| State | System | Panels | Gross cost | Payback |
|---|---|---|---|---|
| California | 6.8 kW | 15-19 | $13,405-$20,176 | 5.1 years-7.6 years |
| Texas | 6.6 kW | 15-19 | $11,764-$17,579 | 9.7 years-14.4 years |
| Massachusetts | 8.3 kW | 19-23 | $19,294-$28,900 | 8.5 years-12.8 years |
900 kWh per month is SolarCalcNow's default planning example because it sits near many U.S. residential bill scenarios without pretending to match every home.
Use this page when your usage is close to 900 kWh, then refine with ZIP, shade, and export assumptions before quote review.
Same calculator engine with a different starting assumption. Useful before comparing installer quotes.
Monthly usage presets
Panel wattage presets
State calculators
FAQ
Use 900 kWh only when it is reasonably close to the annual average shown by your utility bills. The calculator multiplies monthly usage by twelve, applies the selected offset target, and sizes the system from the state production assumption after shade and system losses. A single high summer or winter bill can overstate the year-round requirement, while a mild month can understate it. Average a full year when possible, keep future electric loads separate until they are understood, and compare the result with your available roof. This preset is a starting input, not evidence that every home at this usage needs the same design.
Replace the preset with your own monthly kWh first, then select the correct state and review shade, panel wattage, target offset, direct solar use, and export value. Those controls affect different parts of the result: production assumptions influence system size, panel wattage converts system watts into panel count, and export value changes annual savings without changing the energy the system is asked to produce. Check the visible source dates and confidence notes before comparing quotes. The displayed cost is gross cost before incentives, financing, batteries, roof work, or electrical upgrades, so an installer proposal should keep those items separate rather than presenting one unexplained net figure.
After calculating, save the estimate assumptions, check incentive status, and compare installer quotes against the same baseline.