A roof covered in solar panels.

How Many Solar Panels Do You Need?

Solar panels are all the rage lately because of their long-term environmental sustainability and the amount to which you can cut down on utility costs. Solar panels use sunlight to power buildings, and many people are starting to integrate solar panels into powering their homes. Solar panels are great, but depending on how big your home is and how much energy you use, it can be quite expensive and space-exhaustive to implement a solar panel system that provides all of the energy for your home. The number of solar panels you need depends entirely on your unique situation, so follow these steps and figure out how big of a system you need to power your home.

Determine How Much Energy You Use

The number of solar panels you need depends entirely on how much energy you use. That means you need to figure out how many large appliances there are in your house that are constantly running on electricity or gas. You then need to determine how many kilowatt-hours (kWh) each appliance uses and add it all up to estimate the amount of energy use per day and per month. You can also just look at your utility bills over the course of the past year and estimate your energy use based on those figures.

Determine How Much of Your Energy You Want to Be Powered through Solar Panels

You may decide that it’s too costly to power your entire house with solar panels, so its important to figure out just how much of your energy you want to cut down by implementing a solar panel system. Want to cut your electricity use down by half? Then simply cut your energy bill figures in half to determine the amount of solar panels you need to power half of your house.

Find Your Sun Hours Based on Location

Since solar panels run on energy from the sun, you need to determine how much sunlight you expect to get throughout a typical day and at various times of the year. Residents from states in the south are likely to get a lot more sun and energy from their solar panels. This means someone who lives in Arizona will probably get more bang for their buck when compared to a resident from Massachusetts or Alaska.

Determine How Much Energy the Solar Cells Produce

Different types of solar panel cells produce different amounts of energy. There are two main types of solar panel cells, single-silicon and multi-silicon, and each produce a different amount of energy efficiency. Keep in mind that the more energy-efficient the solar panel cell is, the more expensive it will be. This means that you shouldn’t just search for the cheapest solar panel seller; you need to really investigate how efficient the cells will be before buying.

Real Life Example:

The average house consumes about 48 kWh of energy per day. A resident from Arizona, for example, receives more hours of direct sunlight and his or her solar panels will produce more energy. The solar insolation per year is around 6 kWh squared per day in Arizona. This means that a resident from Arizona who consumes the average amount of kWh per day will require 53 square panels of at least 15% efficient solar panels or 38 square panels for more expensive 21% efficiency panels. 

Last Updated: December 19, 2014