How Many Solar Panels Will I Need?
If you are thinking about going solar, then one of the most important things you need to consider is how many solar panels you will need to adequately power your home. After all, the last thing you want to have happen is for your system to be sized too small, and for it not to provide you with the amount of clean energy you desired. You also don’t want to install more panels than necessary, as that will only add excess cost to your solar installation.
Getting it right is a matter of knowing what your home’s current energy use is, and how many solar panels will be required to satisfy that demand. This guide will help you learn more about solar panel energy production, so you can work with your installer to ensure you’re buying enough panels for your home.
Determine Your Annual KiloWatt-Hours Used
Your home’s electric usage is measured in KiloWatt-Hours (kWh). To give you an idea of how much electricity your home consumes annually, you will have to refer to your monthly electric bill. Depending on your electric provider, your bill may keep an annual tally running, or it may only provide the prior month’s usage. If it is the latter, then you should print out your electric bills from the last twelve months and add up the monthly KiloWatt-Hours used.
This will tell you how much electricity your home has used over the last year. You can then divide that number by 365 to determine how many kWh your home uses daily. To give you an idea of what to expect, the U.S. Energy Information Administration (EIA) states that the average American household uses 10,649 kWh of electricity per year, or about 29.18 kWh per day.
If you have made changes over the last year that have impacted your home’s electrical demand, like replacing older appliances with newer Energy Star models, then using an online load calculator like the one available from UnboundSolar.com. An online calculator allows you to input individual appliances, their wattages, and approximately how many hours per day they are used.
This will help give you a more accurate and realistic look at your current energy use, however, it does take a little longer to calculate and there is always the risk that you may forget to include something.
Your Area’s Annual Peak Sunshine Hours Also Matters
Solar panels are most efficient when they have a lot of available sunshine to convert into energy. So, the amount of sunshine your area receives annually also plays a role into the number of solar panels you will need to power your home.
A Peak Sun Hours map will give you an idea of approximately how many peak sunshine hours per day the United States receives on a state-by-state basis. It is important to note, however, that just because your region may receive a certain amount of peak sunshine on the map, it is not guaranteed that your home reaches that threshold. Trees and other tall structures could cast shade on your home at various times throughout the day. With solar, even the smallest bit of shade on a solar panel can affect its output efficiency.
The Average Solar Panel Produces 1.24 kWh Per Day
Currently, the average solar panel produces just around 1.24 kWh per day. To get an idea of how many solar panels you will need to power your home, you need to divide your daily kWh usage by 1.24. So, if your home uses an average of 36 kWh per day, and you want a solar system that can provide you with 100 percent of electric demand, then you will need at least 29 solar panels.
Or, if you want a smaller, more affordable solar system to help offset your energy use, but not completely eliminate your connection to the national grid, then you can determine how much energy you want your system to account for and then use the same mathematics to determine the number of panels you will need.