The number you want is on a piece of paper you already have. Your power bill knows how much electricity your house uses, and that usage, not your roof size and not a salesperson's guess, sets how many panels you need. Here is how to get from the bill to a number in about five minutes.
Step one: find your usage
Every electric bill lists the kilowatt-hours (kWh) you used that month. That is the number you build on.
- One month is not enough. Summer and winter are worlds apart on the Gulf Coast, so pull a full twelve months.
- Most utilities show a twelve-month usage graph on the bill or in your online account.
- Add the twelve months up. That total is your annual usage. Call it 14,000 kWh for a typical panhandle house, though yours could be half that or double.
Step two: turn usage into panels
One piece of solar math is worth knowing. A kilowatt of panels here in the Florida panhandle makes roughly 1,400 kWh a year, counting the good sun and the cloudy stretches together. So the ballpark is two divisions:
- Annual kWh divided by 1,400 gives your array size in kilowatts. 14,000 / 1,400 = 10kW.
- Array size divided by 0.4 gives the panel count at 400W each. 10 / 0.4 = 25 panels.
That is close enough to know whether you are shopping for fifteen panels or forty. Your own number will land elsewhere. A small, efficient house might need 6kW. An all-electric house with a pool pump and two EVs might need 16kW. The bill tells a truth no rule of thumb can.
Step three: adjust for what you want
Covering 100 percent of your usage on paper is the common starting point. It is not the only target, and a few things move it:
- A roof that faces the wrong way, or an oak that shades the afternoon, means a few more panels to hit the same production.
- Adding a battery barely changes the panel count, but you want enough daytime surplus to refill it every day.
- A tight roof may size to what fits. Covering 80 percent of the bill is still most of it.
- Do not oversize. Net metering pays full retail for what you use and bank month to month, but leftover credits at year end get bought back at a much lower wholesale rate. Sizing close to your real usage is the sharper buy.
Let the tools do the exact version
The math above is a ballpark, which is all you need to sanity-check a quote. The precise version uses real sun data for your exact address, roof angle, and shading, and it is not a by-hand job.
- The estimate tool sizes the array to your real usage with local sun numbers built in. Give it your address and your bill.
- The system builder turns that size into a real parts list you can price and adjust.
Do the five-minute version first, then check it against the tool. When the two numbers land close, the quote in your hands is honest.