Skip to main content
SolarCalcNow

No email. No phone gate. Just the estimate first.

Fast Home Solar Estimate

Estimate your solar system size, panel count, roof space, cost, savings, and payback in under a minute.

Start here for a fast, contact-free planning estimate; use the dedicated calculators when panel count, cost, or payback is your main question.

Rates and assumptions reviewed July 2026. See sources and update cadence.

System sizePanel countRoof spaceCost range

No email required

Calculate your home solar estimate

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.

Transparent formulas

Built around assumptions you can see

SolarCalcNow starts from monthly usage or bill, state electricity rate, state production assumption, panel wattage, shade, and target offset. It shows a confidence level instead of pretending every home can be estimated perfectly.

Gross cost is shown before incentives. Verified state and local incentives can be added later, but they should never be silently hardcoded into payback without source review.

See the methodology

State calculators

Start with local assumptions

View data sources

FAQ

Common solar calculator questions

How accurate is this solar calculator?

It is a planning estimate, not an installer quote. Shade, roof orientation, utility rules, equipment, financing, permitting, and installer pricing can change the final result.

Do I need my electric bill or monthly kWh?

Monthly kWh is best. If you only know your monthly bill, the calculator estimates usage from the selected state's residential electricity rate.

Does the calculator include solar incentives?

The calculator shows gross cost first and does not apply incentives by default. Incentives change quickly and need source, updated date, eligibility, and active status before being used in net-cost math.

Why does the result show a panel range?

Panel count depends on panel wattage, roof layout, shading, design setbacks, and installer equipment choices. A range is more honest than a single guaranteed number.

Does roof orientation or shade change the estimate?

Yes. South-facing roofs with low shade usually produce more than east/west roofs or heavily shaded sections. SolarCalcNow uses a simple shade level, not a site-specific layout or LIDAR model.

How often are the rates and assumptions updated?

State electricity rates and production assumptions are reviewed on a published cadence, and every figure links back to its source with the date it was last checked. Utility rates and net-metering rules can still change between reviews, so confirm current terms with your utility before signing anything.