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SolarCalcNow

Solar payback calculator

Solar Payback Calculator

Estimate a simple break-even range for a home solar system.

Use this page when you want a simple break-even range from gross cost and annual savings before layering in financing or incentives.

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Estimate solar payback

Enter monthly kWh or electric bill. The calculator uses state-level assumptions and shows the math behind the result.

Planning for new electric loads?

Add a simple monthly usage placeholder before sizing solar. Replace it with your actual bill or device estimate when you have it.

Need more than a placeholder? Calculate EV charging from annual miles and efficiency, then compare current and future solar size. Plan EV and other future home loads

Your estimate

Example result

You likely need 15-19 panels

Estimated 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.

Estimated system size
6.8 kW
Sized for your target offset and system loss assumption.
Likely panel count
15-19
Centered around 17 panels at 400W equivalent.
Roof space
411 sq ft
Includes a spacing factor, not a final layout plan.
Annual production
10,800 kWh
Modeled first-year output at the selected offset; not a production guarantee.
Gross cost
$13,405 - $20,176
Before verified incentives, financing, or battery costs.
Gross cost per watt
$1.98 - $2.98
Before incentives. Useful for comparing installer quotes.
Annual savings
$2,654
Based on state residential rate and self-consumption assumption.
Payback
5.1 years - 7.6 years
Simple gross-cost payback estimate.

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

Production, savings, and payback

Annual production target10,800 kWh
Annual savings$2,654
Payback5.1 years - 7.6 years

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

Save estimates on this device

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.

No saved scenarios yet.

Assumptions behind this estimate
  • California state-level electricity rate and solar production defaults are used.
  • 100% annual energy offset target.
  • 400W solar panels.
  • 14% system loss assumption.
  • Roof area uses about 21 sq ft per panel plus spacing factor.
  • Gross cost range excludes verified incentives, financing, batteries, roof work, and panel upgrades.
  • 55% of annual solar production is modeled as directly used before export.
  • Export value assumption: Partial export credit.
  • Savings are energy-only and exclude fixed charges, minimum bills, demand charges, and time-of-use detail.
  • You provided monthly kWh usage.
  • PVWatts uses a state reference point. ZIP is not geocoded and the roof is unverified. AC yield already includes system losses.

Confidence drivers

  • Overall confidence: Medium.
  • You provided monthly kWh usage.
  • PVWatts uses a state reference point. ZIP is not geocoded and the roof is unverified. AC yield already includes system losses.

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

Evidence behind the estimate

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.

Modeled production

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.

Data period:
NSRDB TMY · PVWatts V8
Source checked:
Next review due:
2026-12-04
NLR PVWatts V8 · author-selected reference pointDownload values and calculation steps (JSON)

Installed cost scenario

$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.

Data period:
Marketplace table updated 2026-08-28
Source checked:
Next review due:
2026-10-04
EnergySage marketplace + SolarCalcNow cost scenarioDownload values and calculation steps (JSON)

SolarCalcNow provides planning estimates only. Results are not installer quotes, engineering designs, tax advice, financing recommendations, or utility interconnection approval.

Optional next step

Want installer quotes based on this estimate?

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

Test payback against the written cash price

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 inputCalculated output
$1.98/W$13,405 → 5.1 years
$2.48/W$16,791 → 6.3 years
$2.98/W$20,176 → 7.6 years

Cost scenarios use the state marketplace average ±20%, not a quote distribution. Keep batteries, roof work, financing and incentives on separate lines. Simple payback divides upfront cost by one year's energy savings; it ignores replacement costs, financing and the time value of money.

Calculated baseline

What the calculator returns for 900 kWh/month

Payback below is simple gross-cost payback. Financing terms, incentive timing, maintenance, and rate escalation are not included.

StateSystemPanelsGross costPayback
California6.8 kW15-19$13,405-$20,1765.1 years-7.6 years
Texas6.6 kW15-19$11,764-$17,5799.7 years-14.4 years
Massachusetts8.3 kW19-23$19,294-$28,9008.5 years-12.8 years

Methodology first

Payback is useful, but it is not the whole story

Read methodology

Simple payback divides estimated gross cost by estimated annual savings. It is useful for early comparison, but it is not a complete financial model.

Financing, incentives, rate escalation, maintenance, inverter replacement, battery storage, roof work, and home sale timing can all change the real economics.

Compare planning presets

Same calculator engine with a different starting assumption. Useful before comparing installer quotes.

State calculators

Start with local assumptions

View data sources

FAQ

Common solar calculator questions

Is payback the same as ROI?

No. Payback is the time to recover upfront cost. ROI also considers long-term savings, financing, and lifetime system value.

Why does payback show a range?

The calculator uses a low/high gross cost range because installed prices vary by home and installer.

Should I compare payback before or after incentives?

Start with gross-cost payback for apples-to-apples quote comparison. Apply verified incentives only after you confirm eligibility with official sources or a tax professional.

What to do next

After calculating, save the estimate assumptions, check incentive status, and compare installer quotes against the same baseline.