Our solar panel cost and savings calculator is the fastest, easiest, and most accurate way to find out how many solar panels your family needs - you don't need to do any math. In addition, we will tell you the average cost of installing solar energy in your home and how much electricity it can save.
However, if you want to write a pen on paper, calculate by yourself and follow these four simple steps to find out how many solar panels you need.
Step 1: Determine your energy use
Check your recent electricity bill and your monthly electricity consumption. In most cases, the total electricity consumption will be displayed at the bottom of the bill in kilowatt hours (kWh).
Your annual energy consumption will give you the best estimate of how many solar panels you need, because the energy consumption fluctuates in different seasons (think about how much electricity you use to turn on the air conditioner in summer!)
Because the energy consumption changes a lot every month, it is beneficial to turn over your monthly electricity bill in the past year, add up the electricity consumption and divide it by 12.
However, just using a utility bill can tell your energy consumption, which is enough to make a rough estimate.
Step 2: Find out the power generation of solar panels in your area
Now that you know how much electricity your house uses in a month, you need to find the amount of sunlight your area receives. This is usually measured by the so-called "solar peak hours", which is essentially the intensity of sunlight in your area.
We have a complete list of the average peak sunshine hours in each state. This is the sunshine you receive every day in your area. We need to know the sunshine you receive every month. To do this, simply multiply the daily peak sunshine hours in your state by 30. On average, the peak sunshine hours in the United States are between 120 and 150 hours per month.
The maximum sunshine hours you get in a month tell you how many kilowatt hours of electricity can be generated by a 1 kilowatt (kW) solar panel in your area in a month. Therefore, if your state receives 150 peak sunshine hours per month, 1 kilowatt of solar energy will generate 150 kilowatt hours of electricity per month.
Don't know the difference between kW and kWh? Read our guide about kilowatts and kilowatt hours and what they mean.
Step 3: Calculate the size of the solar system you need
Now that you know how much 1 kilowatt solar energy is generated in your area, you can determine how large a solar system you need to meet your power needs.
Divide your monthly power consumption by the monthly sunshine peak hours in your area to get the system size you need (kW). For the average American family, the calculation results are as follows:
893 kWh/135 month solar peak hours=6.61 kWh
Step 4: Calculate how many solar panels you need
So, you know the size of the solar system you need to cover your energy consumption. What should we do now? To figure out how many solar panels you need, multiply the size of the solar system by 1000 and convert the size from kilowatts to watts. Let's use the same example as before:
6.61 kW solar energy x 1000=6610 W solar energy
Next, take the wattage of the system and divide it by the wattage of the solar panel you want to install. The average size of solar panels in the United States is about 370 watts. In our case, this means that you need 18 solar panels to meet your energy consumption.
6610 watts of solar energy/370 watts of solar panels=18 solar panels
Look! This is the number of solar panels needed to power your home.