How many solar panels you can fit on your roof is determined mostly by your roof size and your energy requirements. The ideal situation is having a roof much larger in proportion to how many solar panels you need to meet your energy demands.
The reason for this is to allow enough space not just for the solar panels but for “breathing room” as well. The breathing room is the space around or between the solar array that will allow for easy access to the solar panels whenever there is a need for maintenance work. You want your installer to be able to easily move around to perform repairs or service your solar array.
The average home has a roof size of around 1,600 square feet. Solar panels have an average size of 17 square feet. Allowing for obstructions like chimneys, pipes, or skylights you could fit anywhere between 80 to 90 solar panels on a roof.
But how much roof space is enough space? That is the question we will definitively answer in this post. By the time you reach the end of this article, you will know how to calculate how many solar panels you can fit on your roof.
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You will also find out how many solar panels the average home fits, how much of the roof you can cover with solar panels, and whether you can put solar panels on different sides of a roof.
How Many Solar Panels Can I Fit on My Roof Calculator? (Factors)
To calculate the number of solar panels you can fit on your roof, you need to know the size of your roof and your energy requirements. Once you’ve measured both you can then map out where and how to fit the solar panels.
Calculating how many panels you will be able to fit is a simple two-step process where you answer two questions. How big is your roof and how much energy do you need?
Calculating roof size
The easiest way to work this out is if you have the blueprints of your home. They will have an accurate measure of your roof dimensions. If you don’t have the blueprints then that means you are going to have to physically measure the roof with a tape measure or string.
When taking the measurements, you should only measure the areas where you can place the solar panels. Be careful to exclude areas like chimneys or skylights where you cannot place solar panels. Once you have measured you will know how much space you have to work with.
When you take your measurements also be cognizant of leaving space for a walkway between and around the solar panels for installation and maintenance.
Calculating your energy requirements
Working out how much energy you will need is a little more complicated than getting out a tape measure. You will need to know your energy consumption and how many solar panels will produce enough energy to meet your consumption.
The simplest way to get your energy consumption is to look at your energy bill over the last 12 months. It should tell you your consumption as a kilowatt-hour unit measure (kWh). The average residential consumer in the U.S has a monthly consumption of around 877 kWh. (Source)
Rounding that off to 900 kWh and dividing by 30 gives you 30 kWh, which is the daily energy requirement. Now you know how much energy you need. But how many solar panels will produce that amount of energy?
This will be determined by how much sunlight the solar panels receive. Some areas receive more sunlight than others. Someone in California will need fewer solar panels than someone in New York as there are more peak sunlight hours in California than there are in New York.
If for instance your home consistently receives 5 hours of peak sunlight, your solar panels would have to produce 6,000 watts to meet your energy requirement of 30 kWh.
30 kWh / 5 hours = 6,000 watts
Working out how many solar panels you need now becomes a simple matter of dividing the watt rating of a solar panel by the total watt output. The average homeowner in the U.S can have their solar energy requirement met with between 20 to 25 solar panels. (Source)
How Much of The Roof Can I Cover with Solar Panels?
You can cover every square inch of available space on your roof with solar panels but this is neither practical nor structurally sound. Covering an entire roof with solar panels would put too great a load on it and the solar energy produced would likely exceed what you need to cover your energy requirements.
Solar panels weigh between 35 to 45 pounds each. That is without including the added weight of equipment to attach the solar panels to the roof. A roof covered in solar panels would be like having a second roof on your existing roof!
Besides placing unnecessary load pressure, squeezing too many solar panels into a limited space makes them difficult to access for maintenance. They would also produce energy, far above what you would use.
There are regulations limiting how much of your roof can be used for solar. Depending on your jurisdiction you will only be allowed to install a certain number of solar panels. This is partly to allow firefighters access in the event of an emergency. (Source)
How Many Solar Panels Can the Average House Fit?
The average home has a roof size of around 1,600 square feet. Solar panels have an average size of 17 square feet. Allowing for obstructions like chimneys, pipes, or skylights you could fit anywhere between 80 to 90 solar panels on a roof.
While you could fit all those solar panels in theory it would not be advisable in practice because of the load weight, overproduction of energy, and regulations prohibiting it.
Can You Put Solar Panels on Both Sides of The Roof?
You can put solar panels on both sides of the roof. This has the advantage of maximizing energy production by capturing sunlight at different times of the day. These are known as “multiple string” solar systems.
A group of two or more solar panels wired together is called a string. You can have more than one string of solar panels in your system. You might need to have multiple strings if your roof has an irregular shape or if you just want to take advantage of having two or more strings on different parts of your roof.
A multi-string solar system has a slightly different design from a single-string system. The biggest difference is that a multi-string system uses a multi-string inverter to control the energy input from the different strings of solar panels.