0
0
0
0
This is one of the first questions people looking to install a solar panel system tend to ask. As we mentioned in our last Back to Basics post, one factor that determines how many panels you need is how much energy your home uses. Of course, this depends on how big your house is, how many electrical appliances you use and if those appliances have good Energy Star ratings.
According to the U.S. Energy Information Administration, the average household consumed 11,040 kWh (kilowatt hours) per year, or 920 kWh per month. Maryland, is slightly above that, with household consuming more than 1,000 kWh per month (see this spreadsheet for energy consumption information for each state).
Now, consider that a high-efficiency panel that’s 32 x 60 inches will generate 185 watts per year. That means that you would need approximately 60 panels if you wanted to cover your entire annual electricity usage (provided you consume the national average). And that would be 160 x 300 square foot roof!
Since very few of us have that size roof, we therefore need to make realistic expectations about the size of system we that we can really afford. To do that, we need to look specifically at your energy usage, the size of your roof and the amount of sunlight it receives. We then put all those numbers into a cost/benefit analysis to show you exactly how much you can save based on a realistic estimate of the size of the system your home can handle.
Sidenote: There’s far less financial benefit to purchasing lower-efficiency panels. Ultimately, they produce less energy, meaning that you need more panels to create the same amount of energy.