How Many Solar Panels Do You Need?

Solar power is on the way to becoming a vital alternate power source across America. In fact, California has mandated that from 2020 onwards, all new single-family homes need to have solar panels installed.

However, many people have already adopted, or are interested in adopting, solar power even without the mandate. For those interested in adopting solar power, there are many questions they may have. Questions such as the power output, efficiency, and how many panels they might need. Keep reading for answers to those questions.

What is Your Monthly Energy Usage?

In order to find out how many solar panels you may need, you should first find out your average energy consumption each month. This is very simple to do. Just look at your electric bills for the past few months and calculate the average number of kilowatt hours (kWh) used each month. If you want to get more granular, you can calculate the number of kWh used each day; simply divide that number by 30 to discover your daily kilowatt usage.

Figuring Out How Many Solar Panels You Need

Once you have figured out your energy usage, your next step is choosing a solar panel type to fit your needs. There are several factors to consider, such as the energy output of the panels, their efficiency, and the size of your roof.

The Energy Output of Solar Panels

Each solar panel has an efficiency rating that shows how much power it produces per hour of sunlight. So, if a solar panel has an efficiency rating of 250, then it will produce 250 watts of energy each hour. You multiply that number by 4 to find out how much power the panel produces each day. The reason is that solar panels receive the most energy when the sun is at its brightest, which is about 4 hours each day.

So, the simple formula is to multiply the efficiency rating by 4 to find out the daily output of a single solar panel. The output would be slightly higher since there is more sunlight each day, but the number gives you a good idea of the panel’s energy output. So, the energy output of this panel would be the following:

250 x 4= 1000 watts

Remember that 1000 watts = 1 kWh, so the panel produces roughly 1 kWh each day.

The Number of Solar Panels Needed

This depends mostly on the size of your roof, but also how much you want your solar installation to offset your energy usage. To do this, you will need to find out the daily energy output of any potential solar panel and multiply it by the percentage of energy you want to save.

If you use an average of 35 kWh per day and want to offset 70% of it, then you would need to find out how much energy each panel produces per day and multiply it by 0.70. So, in this example:

35 x 0.70 = 24.5

If each panel produces about 1 kWh of energy each day, then you would need about 25 panels to produce 70% of the energy your home uses each day.

Once you have made these calculations, you need to find out if your roof can hold the requisite number of panels. If it cannot, then you may need to consider more efficient panels that will convert more of the solar energy into electricity.

There is a Solar Solution for Everybody

The main calculation you need to think about when deciding on the number of panels you need are:

  1. Your home’s daily energy consumption.
  2. How much of that consumption you want to offset via a solar installation.
  3. How many solar panels your roof can hold.

Once you have figured out these variables, you can start deciding on the STC of the panels you are considering and how many of them are needed to provide the energy offset you want. This means that homes with larger roofs do not need to use the more expensive, energy efficient panels. Smaller homes may need them because the limited roof space means more efficient panels are necessary.

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