How Many Solar Panels Do I Actually Need?

We get a lot of questions from potential clients about how many solar panels are needed for their homes. Unfortunately, the answer isn’t cut-and-dried. How many solar panels to use on your house depends on your goals, your house and your budget.

Most people go solar to reduce their electric bills and to improve their environmental impact. After last summer’s crazy high temps and shockingly high electric bills, we can understand how you might be motivated to go solar. Luckily, now is a great time of year to start your decision making process.

But figuring out how many panels you need on your house isn’t necessarily an easy task. How many panels you have on your house directly impacts the cost of the system and amount of power produced.

We should say right up front that Fusion Power will do all of the relevant calculations for you when we assess your house for a new solar system. But we also know there are lots of people out there who like to educate themselves before they make a major decision like installing solar panels on a house. Here’s how to do your own rough calculations:

Calculating How Many Solar Panels You Need

• First you will need to calculate your hourly electrical usage. You can find the monthly usage on your electric bill and divide by 30 to get a daily average, then divide by 24 to get your hourly average. However, we do know the average electricity consumption in Arizona is 1061 kWh per month, according to ElectricityLocal.com, making average daily usage about 35kWh and hourly use 1.45kWh.
  There are 1000 watts per kW, so multiply that by 1000 to get the number of watts: 1450 watts/hour.
• Next figure out how much sun your panels will receive. Thankfully you won’t need to stand outside all day to calculate this number. The National Renewable Energy Lab notes peak sun lasts for about 6.5 hours a day on average in Phoenix. (That number can fluctuate greatly, from 4.5 hours in December, to 8.08 hours in June.)
• Decide how much of your total power you would like to come from solar. For this exercise, we’ll say 100 percent. If you were to go with a lower number, say 80 percent, you would multiply the final number below by .8.
• Now, let’s do some math! Multiply your hourly energy usage by the average peak sunlight hours, then divide that by the panel’s wattage. In this case we will assume the panel is 330 watts. 1450 x 6.5 / 330 = 28.5 panels

Solar Panel Efficiency and Cost

Let Us Calculate Your Solar Needs For You