☀️ Solar Savings Calculator
Estimate what a rooftop solar system would produce, save on your bills, and avoid in CO2 — plus how many years until it pays for itself — from its size, your sun hours, your rate, and the install cost.
☀️ Size Up Your Rooftop Solar
What is a Solar Savings Calculator?
Rooftop solar turns sunlight into electricity you would otherwise buy from the grid, cutting both your bills and your carbon emissions. This calculator estimates how much a system of a given size will generate in a year based on your local sun hours, how much money that offsets at your electricity rate, and how long it takes to recover the install cost.
It also projects the CO2 avoided over a 25-year system life, so you can see the climate payoff alongside the financial one. Real output depends on panel orientation, shading, weather, and gradual degradation, and local incentives can change the economics — so treat these as planning estimates and confirm with a qualified installer.
❓ Frequently Asked Questions
How does the solar savings calculator work?
It estimates annual production by multiplying your system size in kilowatts by your average peak sun hours per day and by 365 days. That production times your electricity rate gives your yearly bill savings, and the install cost divided by those savings gives a simple payback in years. Production times your grid's carbon intensity gives the CO2 avoided each year, projected over a 25-year system life.
What are peak sun hours and what number should I use?
Peak sun hours are the equivalent hours per day your panels receive full-strength sunlight — it bundles the day's varying light into one figure. Sunny regions like the US Southwest average 5 to 6 hours, while cloudier northern areas may see 3 to 4. A solar irradiance map or a local installer can give you a value for your roof; 4.5 is a reasonable middle estimate.
Is solar worth it financially?
In many places, yes — especially where electricity is expensive and sunlight is plentiful. This tool shows a simple payback period, often in the range of 6 to 12 years, after which the electricity is essentially free for the panels' remaining life of 20 to 30 years. Local incentives, tax credits, and net-metering rules can shorten payback further but aren't included here.
How much CO2 does rooftop solar avoid?
Every kilowatt-hour your panels generate is one your utility doesn't have to supply from the grid, so the CO2 avoided equals your production times the grid's carbon intensity. On an average grid a typical home system can avoid several tonnes of CO2 a year, adding up to 100 tonnes or more over its lifetime. The cleaner your grid already is, the smaller the emissions benefit.