Is your home a good fit for solar? Five questions decide it

1. Do you own the roof, and will you stay?

Solar is a 25-year purchase that usually takes 8 to 15 years to pay for itself. If you rent, or expect to sell within five years, the arithmetic is harder. Panels do tend to add value at sale, but buyers pay for them unevenly, and a leased system has to be transferred to the new owner.

2. Does your roof face the sun?

In the United States the sun sits in the southern sky. A south-facing roof collects the most energy. Southwest and southeast lose only a few percent. East and west roofs typically keep 80–90% of south. North-facing roofs are the hard case: in the north they keep barely half.

Type your address into the planner to see which side of your roof works, drawn to scale.

3. Is it shaded?

Shade is the silent killer of solar output. One large tree over the roof can cost more production than a poor roof direction. If your roof is in shade for much of the middle of the day, solar is unlikely to pay. Light morning or evening shade is normal and is already allowed for in standard estimates.

4. How much do you pay for electricity?

Solar saves money by replacing electricity you would otherwise buy. It pays fastest where power is expensive. Homes in Hawaii pay about 46¢ per kWh, in California about 33¢, and in parts of the South and Midwest about 13–15¢. See every state.

5. How does your utility treat the power you send back?

At midday most homes make more solar power than they use, and the surplus flows to the grid. Some utilities credit it at the full retail price (net metering). A growing number credit it at a fraction of that (net billing). The difference can add five years or more to your payback. Chapter 6 explains it.