Estimates, not measurements
Results are calculated from the values you enter. They are not readings from your utility meter and should not be expected to match an invoice exactly. Fixed charges, taxes, tiered tariffs, time-of-use rates, demand charges, export rules, and missing appliances can change the actual amount payable.
Equipment assumptions
Rated input power may differ from average operating power. Refrigerators cycle; air conditioners vary with weather and load; computers change draw with workload. Where a tool uses a running fraction or estimated annual output, that input is an assumption unless it comes from measured or site-specific data.
Safety
Do not open appliances, expose conductors, or make unsafe electrical measurements to obtain a number for a calculator. Follow manufacturer instructions and use a qualified professional for electrical, HVAC, roof, and grid-connection work as appropriate.
Solar and purchase decisions
Solar payback is particularly sensitive to local rules, the value of self-consumed generation, export compensation, equipment lifetime, and financing. Our simple estimate does not guarantee a return or account for every operating cost.
No professional relationship
Use the material as a starting point for questions, not as a substitute for professional advice suited to your situation. By using the site, you acknowledge that the estimates depend on user-supplied inputs and simplifications.