Independent solar math, no installer rankings
What will rooftop solar cost you, and when does it pay back?
Enter a quote you received, or start from the public benchmark. NREL's published residential benchmark was about $3.25 per watt DC in 2024. We compare your quote to that line, estimate production for your area, and show the payback with the assumptions printed instead of buried.
One important change: the federal residential solar tax credit ended for systems placed in service after 2025. This site assumes no federal credit. Check DSIRE for what your state and utility currently offer.
- NREL $3.25 per watt benchmark (2024, checked October 4, 2026)
- EIA electricity price context
- DSIRE and utility tariffs for incentives
- No federal credit assumed after 2025
Try it with a real quote
Bring an installer quote if you have one. The estimator prices it per watt against the benchmark, estimates first-year production from the planning factor for your area, and shows simple payback with degradation and flat prices stated beside the result.
At $3.25 per watt, this quote is in the neighbourhood of the NREL 2024 residential benchmark of $3.25 per watt (checked October 4, 2026). Equipment, roof work, and warranty decide whether it is fair.
- Quoted price per watt
- $3.25
- Estimated first-year production
- 13,200 kWh
- Share of current usage offset
- About 98%
- Estimated first-year bill savings
- $2,112
- Net cost after incentives you entered
- $26,000
- Simple payback
- 12.3 years
- 25-year net (0.5% yearly degradation, flat rates)
- $23,750 ahead
Planning estimate only. Production depends on roof angle, shade, and weather; savings depend on your tariff and net metering rules, which change. The federal residential solar tax credit ended for systems placed in service after 2025, so this tool assumes no federal credit unless you enter a confirmed incentive yourself. Model your roof in NREL PVWatts and check incentives in DSIRE before deciding.
Start with the decision
Metro planning examples
Ten metros worked end to end: production, electricity price, an 8 kW example at the benchmark price, savings, and payback.
Quote red flags
The dollars-per-watt test and the contract lines that separate a fair quote from a padded one.
Net metering, explained
What your exported power is actually worth under retail credit, net billing, and buyback plans.
Every section on this site
Payback estimator
Your quote, system size, bill, and price, compared to the NREL benchmark with payback printed.
Metro cost pages
The same 8 kW benchmark example in ten metros, so sun and rates explain the differences.
State pages
Production expectations, price context, and the incentive and export rules to verify before signing.
Roof types
How shingle, standing seam metal, and flat roofs change mounting, sequencing, and cost.
Guides
Lease versus buy, batteries, sizing, reading quotes, and the export rule underneath everything.
Methodology
Cost basis, production method, savings assumptions, and what the estimator cannot tell you.
Guides
Lease, buy, or PPA: who owns the value on your roof
Own the panels, lease them, or buy the power from someone else's panels on your roof. How the three structures split cost, risk, and the value of your roof.
Do you need a battery? The three jobs storage actually does
A battery roughly doubles the project conversation and often the price. When storage earns its place, and when it is an expensive accessory.
How big should your solar system be?
Too small wastes the roof, too big wastes money on exported energy your utility buys cheap. How annual usage, exports, and roof reality set the right size.
Reading a solar quote: the red flags and the benchmark
The solar quote is the sales document, so read it like one. Seven things that separate a fair price from a padded one, and the benchmark that anchors them all.
Net metering and net billing: what your exported power is worth
Net metering decides what your exported power is worth, and lately the answer is less than it used to be. How retail credit, net billing, and buyback plans change the math.
How SolarRoost builds an example
Planning examples price systems at the National Renewable Energy Laboratory residential benchmark of about $3.25 per watt DC for 2024 (checked October 4, 2026), estimate production with metro planning factors consistent with NREL PVWatts modelling, and use stated electricity prices rounded from U.S. Energy Information Administration data with a stated $180 example bill. Incentives are never assumed: the federal residential credit ended for systems placed in service after 2025, and state or utility programs must be confirmed in DSIRE and your tariff. Read the methodology for the full method, the about page for how publishing works here, and the disclaimer before acting on any example.
Solar is half of the home energy decision
Rates, utility programs, and the wider energy picture live on EnergyBS. SolarRoost covers the rooftop: cost, production, and payback. Read the rate context there, then come back and run your quote here. If you are still choosing a system size, start with the sizing guide and your state page, and price the result in the estimator before you talk to an installer.