Should I cut down trees that shade my solar panels?
It might seem environmentally counterproductive, but it actually makes sense to trim or cut trees to make room for solar panels.
If you want to get the maximum performance out of solar panels, it’s important that they have full sun for as much of the day as possible.
To see the effect of shade on your solar panels, try The Solar Nerd calculator with different values for shading, from none to partial and major shading. You can quickly see that shading has a seriously detrimental effect on how much electricity a solar array will generate.
So, from an energy perspective, it makes sense to clear branches or even whole trees to improve the performance of your existing solar panel system or to prepare a site for a new solar installation.
However, many people install solar panels not just to save money on utility bills, but because they want to contribute to a cleaner environment. If that’s one of the reasons why you’re interested in solar, you might be asking if it makes sense from an environmental point of view to remove trees that are blocking a solar array.
That’s what this article will address, starting with the carbon footprint of electricity.
The carbon footprint and carbon offset of solar panels
In terms of carbon emissions, solar panels are far and away much cleaner than electricity generated from fossil fuels. While solar panels don’t emit any pollution while generating electricity, it does take energy and raw materials to manufacture them.
After looking at numerous studies on the subject we can conclude that, on average, it takes about 3 to 4 years of operation for a solar panel to offset as much carbon as was required to manufacture them. After that, you’re looking at completely emissions-free electricity for as long as the solar panels last, which is often 25 years or more.
This means that once the carbon footprint of manufacturing is “paid back”, a solar array will be carbon negative for the rest of its lifetime - meaning that every kilowatt hour of solar electricity generated results in avoided emissions from power plants on your grid.
How dirty is the electricity from your local grid?
The electric grid is made up of a lot of different power plants, some cleaner than others. For example, where I live in upstate New York, there is a lot of hydroelectricity from Niagara Falls and carbon-free electricity from nuclear power plants.
Because of that, my grid electricity is much cleaner than the national average: about 0.29 pounds of carbon is emitted per kWh of electricity generated. Other parts of the country rely much more on dirty fossil fuels and have correspondingly higher emissions. For example, in Wisconsin, the carbon emissions are around 1.7 pounds per kWh.
To find out how dirty your electricity is, enter your zip code into the EPA’s Power Profiler tool. It’ll tell you how much CO2, SO2, and NOx pollution is created by your local electricity supply.
How many trees does it take to offset your grid electricity use?
If you scroll a little bit down on EPA Power Profiler page, you will see another calculator called Estimate Your Emissions. This is a handy little tool that translates these pollution numbers into something a little more tangible - like how many trees it takes to offset your electricity.
To use the tool, just enter your average monthly electricity usage in kilowatt hours. If you don’t know what that is and you’re too lazy to check your latest electric bill, just use the national average of 1,011 kWh.
Once you plug that in, you’ll get a report showing how much pollution your electricity usage generates. It’ll look like this:
Under the Annual Results section of the report, you’ll see some interesting facts, one of which is the number of trees you would need to plant every year to sequester the carbon dioxide that results from your electricity use. Here’s the report for my usage in upstate New York:
It would take 26 seedlings grown for 10 years or 1 acres of forests in one year to offset those CO2 emissions.
My electricity usage is lower than average - about 600 kWh per month. And my grid electricity is also cleaner than average. But even so, I would need to plant 26 trees every year to offset my grid electricity usage.
If greenhouse gas emissions are what you care about, cut the trees down
Fortunately, I don’t use much grid electricity - I have 18 solar panels on my home that supply nearly all of my electricity usage. That means my solar electricity has a carbon offset equivalent to planting more than 20 trees a year.
Your calculation might be different - probably higher, because the electricity supply is dirtier on average than what we have here in upstate New York.
All of this is just a roundabout way of saying that, from a greenhouse gas perspective, the math is overwhelmingly in favor of cutting down a few trees so that you can have a well-functioning solar array.
Other environmental considerations
This article only touched on greenhouse gas emissions, but of course there are other environmental benefits from trees that are a little harder to quantify. Trees provide shade, food and habitat for animals, and natural beauty - all important things. Whether those things are more important to you than the pollution benefits of solar electricity is up to you to decide.