Homeowners deciding to install solar panels often wonder how much electricity their roof will generate. Every roof is different, so it’s hard to say precisely how much energy your roof can produce. However, you can use this guide to know how much electricity you can theoretically produce from solar on your roof.
We will look into factors that determine how much solar your roof can generate, which include roof size, solar panel direction, amount of sunlight in your area, shade, and type of installed solar system.
How much solar energy can your roof generate?
To answer this question, you need to lay down several factors. Let’s use an example below:
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- We will use the U.S. average roof size of 1,700 square feet of open, available roof space
- Daily U.S. average 5 hours of sun-hours or direct sunlight
- 300-watt solar panels with 60-cell that are 17.5 square feet in size (5.4 feet tall by 3.25 feet wide)
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First, you need to know how many solar panels can fit on your roof. Assuming that all your roof space is usable for solar, divide 1,700 square feet by 17.5 square feet per panel, and you get 97 panels.
Multiplying 97 by the 300-watt solar power output of each panel gets us a system size of 29kW. Finally, 29kW multiplied by the number of sun hours and 365 days a year will be 52,925 kWh of system production per year. (29 x 5 hours x 365 days). This is way more than the 2021 average annual electricity consumption for a U.S. residential utility customer, which is 10,632 kWh or 886 kWh per month.
Note that the figures above are for a perfect roof without obstructions like chimneys and vents. The result will vary depending on the actual roof design and available space for solar panels. Solar installers will only install panels up to the edge of your roof, or they’ll run into issues like vents or chimneys that take up space, so your roof space will be reduced significantly.
How much solar power you can generate by state
Your geographic location directly affects the quality and duration of your sun hours. The average sun hours in the U.S. is 5 hours which is what we used in the example above. Below is a list of the average peak sun hours and the estimated yearly kWh of energy in your state:
Other key variables should be considered in determining how much solar your roof can, as these affect your roof’s potential solar generation.
Factors that affect how much power your solar panel system generates
Consider several variables when estimating how much solar energy you can produce. Here is the list you can use as a guide:
Roof space
Adding more solar panels can effectively increase the amount of solar energy your roof produces. The wider the available roof space for solar installation, the more solar panels you can install, and, in turn, the higher the potential energy production. For example, suppose your roof has a limited space of 500 square feet for solar installation. In that case, you can only put up 28 panels and generate around 15,330 kWh annually (if using the formula above).
Location and amount of sunlight
You can install as many solar panels on your roof as you’d like, but only those directly hit by the sun can generate power. The sunlight that hits your solar panels is a key factor in calculating how much energy your roof generates. The energy the system produces is relative to their size and the time they’re exposed to sunlight. In general, southern states have better solar energy resources than northern states because they’re closer to equatorial regions with higher average temperatures and longer stays during summer.
The angle or tilt of the panel
The angle at which your solar panels are installed is a key factor in determining how much solar energy your roof produces. If the angle doesn’t catch most sunlight during peak hours, your solar panels can generate less. Ideally, your solar panels should be installed close to or equal to the latitude of your home. This is typically between 30 and 45 degrees to ensure you get the maximum average output from your solar panel system. . In states like New York or Michigan, where the sun sits much lower in the sky, solar panels require more tilt to achieve optimal solar energy production.
Roof Orientation
The most important factor in the energy production of solar panels is their orientation. We already established that solar panels should be facing toward the sun. South-facing panels are optimal because they capture the most sunlight throughout the day. West-facing solar panels, on the other hand, produce more energy in the most critical hours of the day. This is recommended for homes where the Time-of-Use schedule applies. Expensive hours tend to occur later in the day, so solar panels that produce more energy during peak demand hours may financially benefit you.
Equipment size, performance, and power
Your solar equipment size will also affect how much your roof can generate. The greater the wattage capacity of the equipment, the more energy it can produce. That’s why knowing how much energy you need to power your home is crucial.
Most often, homeowners who choose to install solar with just enough capacity for their needs end up regretting not installing greater capacity to grow into. Realistically, once you install panels, people tend to use more electricity. The downside of upsizing your solar panels is that it upsizes your costs too.
But not all the sunlight that hits the solar panels is converted into electricity. Most of it is lost because of multiple factors, including shade, temperature, orientation, and angle. A solar monitoring system will help you track the performance of your solar panel system. In DroneQuote’s video here, we have discussed how solar panel monitoring system works and how this can save you thousands of dollars.
Contact DroneQuote for your solar needs
The samples we’ve provided in this blog post are generic calculations and could be far from the actual computation. To get a precise result, we consider the homeowner’s site condition when forming personalized quotes tailored to fit your needs.
DroneQuote understands that, and we are here to be your solar fiduciary and give you honest input and assessments of how many solar panels you need for your home. You can check on clients’ feedback to show how we value our clients’ needs and interests above all. Get started on your solar journey, and contact us here.