Understanding this quick estimate
What the rule-of-thumb assumptions mean
This tool assumes an 80% bill offset and no federal tax credit, the accurate 2026 default for a new owned purchase, two reasonable defaults for a first pass. A $22,000 system with a $150 monthly bill produces a net cost of $22,000 and assumed annual savings of $1,440, for a rough payback of about 15.3 years. If you have not sized the system yet, start with the quick 5-minute system size estimator and bring its kilowatt figure back here.
Why this number differs from a full calculation
The full payback period calculator uses your actual annual savings figure rather than an assumed offset, which typically produces a shorter and more accurate payback estimate once real usage and rate data are known. Treat this quick number as a starting point, not a final answer. The US Energy Information Administration's electricity data show how retail rates have moved, which is the starting point for any savings estimate.
When a quick estimate is useful
This tool is built for the earliest stage of research, before you have a formal quote or a detailed usage history. It gives a fast sense of whether solar looks worth exploring further, without needing to track down a bill or calculate offset percentages first.
Getting a more precise number
Once you have real inputs, the solar savings calculator and payback period calculator both use your actual figures instead of assumptions, giving a meaningfully more accurate result.