Free Quote Check

Enter the figures from your quote. Price is compared with the average quoted price in your state, production with the estimate for your ZIP code, and the return with a market benchmark.

No federal tax credit is applied. The residential credit ended on December 31, 2025.

Free Quote Check

Used to look up solar production, the electricity rate, and the incentive programs for the ZIP code.
Electricity use (enter one)

Enter your average monthly electric bill. Monthly kWh is more precise, because the bill includes fixed charges.

Enter the contract total from the quote, not a monthly payment.
System size is listed on the quote, sometimes in watts (7,500 W is 7.5 kW).
Heating system
Cooling system
Utility credit for exported power

If the credit is unknown, the results are calculated at both ends of the export-credit range.

Additional Details (Optional)

Use these fields to improve the production comparison, the roof limit, the size-limit check, and the savings.

Enter the first-year production stated on the quote. It is compared with an independent production estimate for the ZIP code.
Enter the number of panels on the quote. With the system size, it is used to calculate the wattage of each panel.
Enter this figure from the site plan or layout drawing, if the installer provided one. It is converted to kW at the quoted panel wattage.
This figure is compared with the payback period.
Enter the fixed customer or service charge from the bill. It is not reduced by solar production, so bill savings and export credits are valued at the per-kWh charges only. The looked-up electricity rate is an average that includes fixed charges, so this charge is taken out of it. The charge is also subtracted from the bill before the home's usage is estimated. If the field is left blank, the typical charge in the state is used. It is looked up when the quote is checked.
Enter any recurring monthly fee for the solar system or its meter, from the quote or the utility. It is deducted from the savings in every year.
Enter the inverter warranty from the quote. It is used only when an inverter replacement cost is entered under Assumptions, because by default the maintenance cost includes the replacement of failed components. The replacement is then charged in the year after the warranty ends, and not at all where the warranty covers the whole analysis period.
Select the inverter technology listed on the quote. It does not change the figures in this check. It is passed to the in-depth report if you order one.
Per-kWh production payment

Enter a payment made for each kWh the system produces, such as a performance-based incentive, with the number of years it is paid. It is paid on each year’s production, not deducted from the price. Where the quote states only a dollar total for such a payment, ask the installer for the rate per kWh and the number of years.

Utility size limit
Assumptions (Optional)

Each field shows its default, or states that the value is looked up for your ZIP code. To replace a value, enter your own figure. To return to the default, clear the field.

Primary Assumptions

Energy price escalation and the market benchmark have the largest effect on the result.

defaultAccording to the EIA Electric Power Annual (Table 2.4), the average US residential electricity price was 12.52 cents per kWh in 2014 and 16.48 cents per kWh in 2024, an increase of approximately 2.8% per year. This analysis uses 2.8% per year.
S&P 500 (1928 to 2025 average), 10.0% per year. Risk: High. Declines of 50% have occurred twice since 2000. This is the investment alternative. Its return, less tax, is the required return for this system.

Roof

The direction the panels face. The default is south (180°).
The direction the panels face, in degrees, as stated on the quote: 180° is south, 90° is east and 270° is west. Enter a number from 0 to 359. If you enter it, it replaces the roof direction. Leave the field blank if the quote does not state it.
defaultThe roof's slope. The default is 20°, a moderate slope typical of houses. Source: NREL PVWatts version 8 residential default.
defaultLosses from dirt, shade, wiring and other causes. The default is 14%. Source: NREL PVWatts default losses. For a shaded roof, enter the annual sun access instead.
The percentage of the year's sunlight that reaches the panels without shade, as stated in the installer's shade report. Some installers call it solar access. Without a figure, production is estimated with a standard sun access of 97%. A figure you enter is used in its place. Leave the field blank if the installer did not state a figure.

Looked-Up Values

This is the utility's average residential rate where a recent figure is published. Otherwise, it is the state average. It is not the rate on your tariff. To replace it, enter the rate from your bill: the total of every per-kWh charge, including supply and delivery.
defaultEnter the total of the one-time incentives listed on the quote, such as state, city or utility rebates. This total is deducted from the price. Do not enter a payment made for each kWh the system produces, such as a utility production incentive. Enter that payment under Additional details, as a rate per kWh and the number of years it is paid. The programs listed for your ZIP code are not deducted, because they are not on the quote and many depend on household income. They are shown with the results under Assumptions and sources, as programs to ask the installer about.
The source is EnergySage's average of marketplace quotes in the state. In Alaska, EnergySage's national average is used. This value is used for comparison only.
The EPA eGRID output emission rate for the grid subregion that serves the ZIP code, or for the state where the subregion is not known. This value is used to calculate avoided emissions.

Modeling Assumptions

defaultThis period was selected for this analysis. It equals the standard performance warranty period for residential solar panels.
defaultThe median in NREL PV degradation studies (Jordan and Kurtz) is approximately 0.5% per year for modern modules.
defaultAnnual Technology Baseline 2025, residential PV, published by the National Laboratory of the Rockies (NLR): a fixed operations and maintenance cost of $29.83 per kW-DC per year for 2024, of which $26.65 is for the system and $3.19 for administration. The cost categories include asset management, insurance, cleaning, vegetation removal and component failure.
defaultNo separate inverter replacement is included by default. The Annual Technology Baseline lists component failure among the costs in its maintenance figure. In its solar cost benchmark for the first quarter of 2023, the National Renewable Energy Laboratory states that its operations and maintenance cost model includes corrective maintenance to replace components, with inverter failure rates based on data from Sandia National Laboratories (NREL/TP-7A40-87303, page 31).
defaultThe typical service life of a string inverter is 10 to 15 years, compared with a 25-year panel warranty. This year is used only when an inverter replacement cost is entered. Microinverters typically have longer warranties than string inverters.
The share is calculated hour by hour from typical usage patterns for the state. In Alaska and Hawaii, where those patterns are not available, 40% of production up to the home's annual use is assumed. A share entered here replaces the calculation.