01 Your system & quote
Start from a preset, then adjust to match the quote in your hand.
The full contract price — panels, inverter, labor, permits. Cash price if they gave you one.
The 30% federal residential credit (Section 25D) ended Dec 31, 2025 — for systems installed in 2026 it is 0%. Leave at 0 unless you have a confirmed, different credit.
Rebates, state credits, or SREC value you are confident you'll actually receive.
02 Your roof & utility
Sun and electricity prices decide everything. Pick your state — production is pre-filled from typical yields.
If your quote lists a Year-1 production estimate (kWh), divide it by system size and enter it here — that's more accurate than any state average.
Use your bill's all-in rate: total $ ÷ total kWh. Delivery charges count.
100% = full 1:1 net metering. Many utilities now pay 25–75% of the retail rate for power you send back. Check your utility's current policy — it changes the answer a lot.
03 Money assumptions
Kept visible on purpose — a report that hides its assumptions is selling you something.
US residential rates have risen roughly 3%/yr long-term. Higher escalation = faster payback.
String inverters typically last 10–15 years. Microinverters often carry 25-year warranties — set to $0 if yours does.
Your verdict
The report file is generated on this page from your numbers — year-by-year table, financing breakdown, and the questions to send your installer before you sign.
Not financial advice — estimates from the numbers you entered. Verify with a licensed installer before signing anything.
Cumulative cash flow
Every year, after all costs. Crossing zero = you've got your money back.
Tap or hover the line for year-by-year values.
Red-flag check
The checks a careful engineer runs before signing anything.
What if the future disagrees?
Same system, three futures. If even the pessimistic case pays back, the deal is robust.
Pessimistic
Rates rise 1.5%/yr, production 10% below estimate
Your inputs
Exactly the assumptions on the left
Optimistic
Rates rise 4.5%/yr, production as quoted
Year by year
Production degrades 0.5%/yr. Savings include export credits and, if financed, loan payments.
| Year | Output kWh | Rate $/kWh | Net saving | Cumulative |
|---|
The Pro Report — what the free calculators won't show you
Free tools stop at payback. The Pro Report is the document you send back to the installer: it prices the financing tricks, stress-tests the production promise, and gives you the exact questions that make quotes drop.
- Dealer-fee & loan true-cost breakdown
- Production estimate audit vs. your roof
- Net-metering policy impact, year by year
- Cash vs. loan vs. lease side-by-side
- 12 questions to ask before signing
- Negotiation targets: fair $/W for your state
Launch offer for the prototype: the full report downloads free today, generated from your numbers above.
How this is calculated
Production: system size × state yield (typical values consistent with NREL PVWatts results for a well-sited residential roof) × roof factor, degrading 0.5%/yr. Savings: solar you use yourself offsets the full retail rate; surplus is credited at your export %; when production exceeds your home's usage, only the exported portion earns the export rate. Costs: net cost after the incentives you entered, one inverter replacement at year 12 if set, and — for loans — monthly payments on principal grossed up by the dealer fee, at your APR and term. Benchmarks: 2026 US residential cash systems commonly price around $2.50–$3.50/W (Lawrence Berkeley National Laboratory, Tracking the Sun); financed systems price materially higher. The US Consumer Financial Protection Bureau has flagged solar-loan dealer fees of roughly 10–30%+ embedded in financed prices. Figures are estimates for comparing quotes — not financial advice, and not a substitute for a site-specific engineering assessment.