Solar energy is becoming more and more ubiquitous, although it remains the type of technology about which new consumers have many questions. Along with other things you’ll need to know when installing solar, one of the most important considerations is how much electricity you’ll need to produce for your home to completely stop relying on the grid for power. Of course, the answer depends on a number of variables, including your energy usage and the type and efficiency of your solar panels. The location of your home and the amount of sunlight it receives are also factors that can vary significantly depending on the season).
That said, it is possible to find estimates based on averages for a typical American household, and also to directly measure your home’s electricity consumption, as well as the likely “energy income” your panels will generate. Another important part of your setup is battery storage, to ensure that you will have enough power in reserve to cover your needs on overcast days or during shortages and peaks in usage. To reduce your electricity bill even further, you can also consider installing some of these additional solar-powered gadgets.
Calculate your energy needs
According to the U.S. Energy Information Administration (EIA), the average American household uses approximately 10,500 kilowatt hours (kWh) of electricity each year, which translates to 875 kWh per month or 28.8 kWh per day. You can find out your personal energy usage by checking your electricity bill (look for a section called “Usage”, “Electricity Consumption” or “kWh” on your monthly statement) or by checking your meter (write down the number today, wait 30 days and subtract your original reading from the new reading to find your total monthly consumption).
Next, you will need to determine how much energy an individual solar panel will generate. A simple way to estimate this is to multiply the panel power by the average maximum sunlight hours and multiply that by the system efficiency. For example, a 400 W panel in a location with 4.5 hours of maximum sunlight and 80% efficiency would give the following equation: 400 × 4.5 × 0.8 = 1,440 Wh. This is equivalent to 1.44 kWh per day. To find out how many peak sunlight hours your location receives, check out a peak sunlight hours calculator. You can also use a solar calculator.
Finally, divide your household’s energy consumption by the wattage of an individual panel to determine how many panels you will likely need to power your home. Going slightly higher will always be better than being below the required output and regularly finding yourself short and having to rely on the grid to make up the gap, hence the 20% rule when installing solar.
