A solar proposal is a sales document. The savings number on it is built from the installer's assumptions about your usage, your utility's future rates, how much of the power you will use yourself, and a tax credit that, for homeowner-owned systems, expired for systems placed in service after December 31, 2025. This page lets you replace those assumptions with your own and see whether the deal still works. If you have already signed, the buyer's guide covers your cancellation window.
What "owning your power" actually costs
The pitch is that you stop renting electricity from the utility and start owning it. Here is the mechanical truth behind that sentence. With a solar loan, your variable monthly power bill is converted into a fixed installment debt of $30,000 to $60,000, usually for 20 or 25 years. The debt is reported to the credit bureaus, Equifax, TransUnion and Experian, as an installment account, the same category as a car loan. It appears on your credit report, it counts in your debt-to-income ratio when you apply for a mortgage or refinance, and a late payment is a late payment regardless of whether the panels are producing. The lender also typically records a UCC-1 fixture filing against the equipment, which a title company will find when you sell. None of that is hidden in the fine print; it is simply not what the salesperson leads with.
Three things follow. First, the comparison that matters is not "solar payment versus old bill" but "solar payment plus the bill you still get versus old bill," because almost nobody's utility bill goes to zero; there is a fixed charge, there are winter months, and under net billing the credit for exported power is a fraction of what you pay to import it. Second, a dealer fee of 15 to 35 percent is routinely folded into the financed amount on "low APR" loans, so the cash price of the same system is often a quarter less than the number on the loan. Ask for the cash price in writing and compare. Third, with a lease or a PPA you own nothing; you have a 20- to 25-year contract with an escalator, and when you sell the house the buyer has to qualify for it and agree to take it, which is where a lot of closings run into trouble.
How the calculator works
- Production starts at the proposal's year-1 figure (or 1,300 kWh per kW if blank, a mid-U.S. value) and declines by the degradation rate each year.
- The share you use directly is valued at your full retail rate. Exported power is credited at retail (full net metering), at your export rate (net billing), or not at all. Under full net metering, exports beyond your imports are valued at $0.03 per kWh.
- Your old bill and the fixed charge rise with the utility escalation rate. Loan payments are a standard amortization. Lease and PPA payments rise with their escalator for the contract term.
- Break-even is the first year the cumulative savings cover everything paid so far (for cash, the purchase price; for a loan, the payments). The 25-year figure is the net position at year 25.
- The battery raises your direct-use share, adds time-of-use arbitrage (80 percent of capacity cycled 300 days a year times the rate spread), and adds whatever you said a year of outage protection is worth. Its resale value is shown two ways: remaining warranty life on a straight line (what a conservative appraiser will accept), and the present value at 6 percent of its remaining annual value (the income approach, see our PV Value critique).
- Nothing is sent anywhere. This page makes no network request with your numbers.