Solar system inputs
Savings, incentives, and financing
This is a planning estimate, not a tax opinion, utility approval, engineering study, installer quote, savings guarantee, or financing offer.
| Line item | Amount | What it means |
|---|
Savings are modeled from entered bill savings, utility inflation, and panel degradation. Real bills depend on weather, usage changes, utility tariffs, export credit rules, minimum charges, equipment performance, and interconnection approval.
Methodology notes
System cost
If system size is entered, gross panel cost is system kW times 1,000 watts times installed cost per watt. If size is 0, the calculator estimates size from annual usage, target offset, and annual production per kW.
Incentives and net cost
Percent incentives are applied to gross project cost, then local rebates are added. Net cost cannot fall below zero. Eligibility, timing, and qualified costs must be verified separately.
Savings and ROI
First-year savings are bill savings minus maintenance and insurance adders. Holding-period value grows savings by utility inflation and reduces output by degradation, then compares cumulative net savings with net project cost and financing interest.
Solar economics depend on installer quotes, roof condition, shading, utility rates, net metering policy, incentive eligibility, financing terms, maintenance, insurance, and how long you keep the home. See full disclosure.
Solar panel cost FAQ
Should I use system size or usage?
Use the quoted system size when you have one. Use annual usage and offset when you are building a rough target before installer designs.
What changes payback most?
Installed cost, net metering value, utility rates, tax credit eligibility, roof adders, financing fees, and how much of your usage the system offsets usually move the result most.
How are leases and PPAs different?
Leases and PPAs are not modeled as owned systems here. They can lower upfront cost, but payment escalators, transfer rules, buyout terms, and incentive ownership change the comparison.