The Environmental Benefits of Solar Energy

Many homeowners turn to solar power as a way to cut monthly electricity bills and gain energy independence. Saving money is just one advantage of home and community solar, though. There are also huge environmental benefits to solar energy. Let’s break down the pros and cons.

As a solar advocate and user myself, I will start with the pros of solar energy for the environment.

Why solar power is good for the environment

#1. Solar power means cleaner air

If you heat your home with gas and you switch to electric heating, your indoor air quality could improve dramatically. Gas combustion is a key source of indoor air pollution, so ditching your gas stove and gas furnace are good moves for a cleaner and greener home.

What if you already have electric heating though? Well, your electricity may still come from coal- or gas-fired power plants, which churn out nitrous oxides, sulfur dioxide, mercury, and particulate matter that cause smog and soot.

In fact, fossil fuel-fired power plants are responsible for 23% of the U.S.’s nitrogen oxide (NOX) emissions and 67% of sulfur dioxide (SO2) emissions, according to the National Renewable Energy Laboratory (NREL). The NREL also notes that greater adoption of solar power could reduce annual NOX emissions by 68,000 to 99,000 tons, and SO2 emissions would be reduced by 126,000 to 184,000 tons.

Signing up for community solar or a green energy provider, or installing solar at home, reduces reliance on these fossil fuels and helps cut emissions for everyone. Switching to solar also lessens the upstream impacts of fossil fuel production and use. This includes methane emissions and other types of pollution associated with fracking.

CO2 emissions saved by going solar

Going solar at home can help cut your carbon emissions. And if you end up producing a surplus of electricity in any given year, you’ll help cut the carbon emissions of others too! 

The U.S. Environmental Protection Agency offers a handy tool to calculate emissions reductions associated with various green lifestyle changes. Using the EPA’s tool, we calculated emissions reductions from a solar array sized to meet 90% of the average U.S. household’s energy needs. The result is the equivalent of taking 1.5 cars off the road each year or planting 113 tree seedlings that grow and sequester carbon for 10 years. Not bad!

Here are the carbon emissions reductions from going solar at home:

This chart doesn’t tell the full story, though, and we like to dig a little deeper at LeafScore. To get a true reflection of carbon emissions from going solar where you live, we have to factor in something called the irradiance or capacity factor. Put simply, the same solar panels won’t produce as much energy in Indiana as they will in Hawaii because the panels don’t have as much sun to work with. 

The table above gives the likely output in kilowatt-hours (kWh) of a solar array based on four peak-sun-hours a day, which is average for the U.S. It’s also the amount of peak-sun-hours you might expect if you live in:

• Alabama
• Delaware
• Iowa
• Minnesota
• Oregon
• Tennessee
• Washington State.

For other states, we can use more accurate data for peak-sun-hours to calculate the likely output of a solar array. At the extreme ends of the spectrum, we have Arizona, with 7.5 peak-sun-hours a day and Alaska, with just 2.5.

Here’s how output and carbon emissions reductions look for those states:

In summary, no matter where you live in the U.S., even a small 2 kW solar array getting just 2.5 peak-sun-hours a day is the equivalent of planting 21 trees a year or not driving nearly 3,200 miles. 

So, when considering how much you can save by going solar, don’t forget to factor in saving the environment.

#2. Reduced carbon dioxide and greenhouse gas emissions

Fossil fuel-fired power plants are responsible for 40% of man-made carbon dioxide (CO2) emissions, according to the National Renewable Energy Laboratory (NREL). The Solar America Initiative launched in 2006 aimed to install 70-100 GW of photovoltaic systems in the U.S. by 2030. Achieving that target could, according to the NREL, reduce annual CO2 emissions by 69 to 100 million tons in 2030.

By going solar, you also reduce your personal carbon footprint and your overall green gas emissions. Even one home going solar makes a difference to the environment.

Let’s look at two examples, the first in Arizona. The average home in this state uses a little less than 13,000 kilowatt hours of electricity every year. Installing a modest solar array of around 6 kW could reduce the draw on the grid by 80%, which would, over 20 years, offset the equivalent CO2 of more than 233,000 pounds of coal (it takes around 1.12 lbs. of coal to produce 1 kWh). 

Put another way, this Arizona homeowner could eliminate the equivalent greenhouse gas emissions of driving 365,892 miles in an average car, according to the U.S. Energy Information Administration. Go a little bigger with that array, to power the home entirely by solar, and the emissions reduction would be even greater.

Arizona is quite sunny though. What about somewhere with less solar capacity, like Connecticut? Even here, the average home solar array could produce more than 8,000 kWh every year. Switching to solar from fossil fuels would be akin to planting 150 trees every year for the life of those solar panels, in terms of reduced CO2 emissions.

#3. Cleaner water and less water use

Manufacturing solar panels does require some water, but the amount needed is far less than with nuclear, natural gas, and coal-fired power plants. These all need huge amounts of water for cooling purposes and can create polluted water waste.

With solar power, there’s no competition for drinking water or water for agriculture. If the U.S. got 80% of its electricity from renewables by 2050, annual water use by coal-fired and natural gas-fired power plants would decrease by about 50%, according to an NREL Renewable Energy Futures Study.

The exception is for concentrated solar power (CSP) or concentrated solar thermal power plants. These, like other thermal electric plants, require water for cooling. The amount of water depends on how the plant is designed and where it is located. CSP plants using wet-recirculating technology can use 600-650 gallons of water per megawatt-hour produced. Dry-cooling design can help reduce water use by 90% or so, however. These designs are less efficient, though, especially at temperatures over 100 degrees Fahrenheit.

#4. Reduced strain on finite resources (and fewer associated military conflicts)

Our planet has only a finite amount of oil, coal, and natural gas. Despite this, we continue to consume fossil fuels as though they’re limitless. This rampant consumption creates a wealth of environmental issues related to resource extraction, transportation, and combustion and also contributes to military conflicts around the globe. And armed conflicts don’t just hurt humans, they also have a devastating impact on the environment. 

Some military actions deliberately damage the environment (remember Agent Orange during the U.S.-Vietnam war?). Most of the environmental impact of war is collateral, though. Explosives can start wildfires, tanks and other armored vehicles destroy vegetation, toxic gases and munitions can pollute the air, water, and soil, and even low-tech trench warfare causes damage to the land.

The awful irony is that as resources deplete further and climate change displaces more people, conflicts are set to grow.

Finding responsible and sustainable ways to bring renewable energy to more people worldwide, and reduce our reliance on fossil fuels, could help turn the tide on climate change.

It could also allow more people to stay in the places they’ve called home for their entire lives. No one wants to be a refugee, but war and climate change have already forcibly displaced millions of people around the world. In 2017 alone, an estimated 22.5 to 24 million people were forced to move because of flooding, forest fires after droughts, and intensified storms.

These are only the acute events though; slow effects of climate change also take their toll, including sea-level rise, ocean acidification, air pollution, desertification, rain pattern shifts, and loss of biodiversity that can lead to famine.

Going solar isn’t a magic bullet, but it can play a part in fighting climate change. The one caveat being that solar panel manufacturers need to act responsibly when it comes to sourcing rare earth minerals and other materials.

The environmental downsides of solar power

Solar power brings a wealth of benefits, but it also has several potential downsides for the environment. Several of these are laid out in a report by the Union of Concerned Scientists and include:

• Excessive land use, land degradation, and habitat loss
• Hazardous material extraction and disposal
• Life-cycle greenhouse gas emissions.

#1. Land use for solar

While residential and commercial rooftop solar arrays don’t require any additional land use, large-scale (utility-scale) solar farms can require 3.5 to 10 acres of land per megawatt. For CSP plants, this can be 4 to 16.5 acres per megawatt. This need not be prime farmland, though. In fact, solar is a great use for abandoned mining land, brownfield sites, transportation and transmission corridors, and sites that require time for remediation.

The field of agrivoltaics is also blooming, with researchers finding ways to make use of the land underneath solar panels. Clearly, solar panels are designed to soak up the sun, which inevitably means less light getting through to plants beneath. For some shade-loving plants, though, this is actually better than constant bright light for many hours of the day. Growing plants under solar panels does make it difficult if not impossible to till, weed, and harvest mechanically, but mechanical tilling and harvesting pose their own issues for soil health.

Sure, some agrivoltaics evangelists are just looking for a way to get subsidies or permits to place solar farms on farmland, but others are genuinely interested in finding ways to actually improve the yield of certain crops. These include raspberries, grapes, and goji berries, all of which are hand-harvested anyway. Positioning crops under solar panels also offers opportunities for less intense working conditions for farm laborers, reducing the risk of heat stroke.

#2. Hazardous materials and solar

Solar panels comprise a mix of metals, minerals, glass, and plastic. Their manufacture involves a variety of hazardous chemicals including hydrochloric acid, sulfuric acid, nitric acid, hydrogen fluoride, 1,1,1-trichloroethane, and acetone. These all pose a risk to worker safety and to the wider environment.

Solar panels also require the mining of quartz to produce silicon, and the acquisition of aluminum, copper, and silver, either from mining or recycled sources. Expansion in the PV industry means most of these materials are freshly mined, which creates potential for environmental degradation and risks to worker safety. Workers producing solar panels also face a risk of inhaling silicon dust. 

It’s also worth noting that some photovoltaics are more problematic than others in terms of the environment. For instance, thin-film PV cells contain more toxic materials than traditional silicon PV cells. These materials include gallium arsenide, copper-indium-gallium-diselenide, and cadmium-telluride. The good news is that while these chemicals are bad for the environment if they aren’t properly handled, they’re also valuable commodities. This means that manufacturers have a strong incentive to reclaim and recycle them.

#3. End-of-life hazards

Standard solar modules have encapsulated silicon wafers, usually wrapped in ethyly vinyl acetate (EVA). This layer of EVA protects the silicon wafer and helps prevent leaching of hazardous chemicals if the panels are maintained and disposed of properly.

Manufacturers are finding ways to streamline recycling, however. This makes it more cost effective and less hazardous. Strategies include building panels in such a way that glass, plastic, and metal can easily be separated. Building panels that last longer and are easier to maintain also helps reduce their environmental burden.

All in all, though solar panel production does involve some hazardous chemicals, there are ways to mitigate risks to health and the environment. And, however we look at it, the risks associated with solar panels are far lower than those from fossil fuels. After all, coal has to be chemically cleaned and treated after mining, and fracked natural gas is extracted using a variety of toxic chemicals. And that’s before they’re burned to produce electricity (and toxic gases). Even nuclear power involves extremely radioactive materials, demonstrating how no power source is without its downsides.

#4. Life-cycle greenhouse gas emissions

Solar electricity generation doesn’t produce any greenhouse gas emissions per se, but there are emissions associated with the production, installation, maintenance, and disposal of solar panels. Estimates of life-cycle greenhouse gas emissions range from 0.07 to 0.18 lbs. of CO2 equivalents per kilowatt-hour for PV systems. For CSP, this increases to 0.08 to 0.2 lbs. of CO2E/kWh.

How does this compare to natural gas and coal? In short, favorably! 

The life-cycle emissions for gas are around ten times higher at 0.6-2 lbs. of CO2E/kWh. For coal, emissions are around 20 times higher at 1.4-3.6 lbs. of CO2E/kWh.

These figures are all taken from the International Panel on Climate Change Special Report on Renewable Energy Sources and Climate Change Mitigation.

Another report, from the NREL found that solar panels’ life-cycle emission intensity is approximately 40 gC02/kWh, or around 0.09 lbs. of CO2E/kWh. In comparison, the life cycle emission intensity of coal was approximately 1,000 gC02/kWh, or 2.2 lbs. of CO2E/kWh. Essentially, to produce the same amount of energy, coal produces 25 times more CO2 than solar. And these calculations were done in 2014, using solar panel efficiencies of just 13.2% to 14.0%. These days, most solar panels are nearly 50% more efficient, with some of the best solar panels nearing the 23% efficiency mark. This means the life-cycle impact of solar is even less these days than it was in 2014.

The environmental payback period for solar panels

Most homeowners considering going solar want to know how long it takes for solar panels to pay for themselves in cost savings. This is known as the solar payback period and averages around 8 years for most home solar arrays.

There’s another way of looking at the return on investment for solar though: the environmental payback period for solar panels. This is the amount of time before a solar power system generates enough electricity to offset the energy required to produce the system (including panels, racks, and so forth). 

Calculations for this will, like the conventional payback period, depend greatly on location and weather. Conveniently, the NREL offers data to help us out. 

According to these numbers, polycrystalline solar panels took just two years to pay back their energy consumption. Again, though, these calculations were performed in 2014, when solar panels were far less efficient. These days, even the average monocrystalline solar panels could generate enough electricity in just a year or two to offset the energy used to produce them. A two-year ROI sounds pretty good!

Solar Panels Energy Payback Time, NREL 2004

‍The true value of solar

When we talk about the cost of solar and the value of solar to homeowners, and even to governments, we usually restrict this to a discussion of direct costs associated with electricity production and distribution. This is frequently because studies into the value of solar are commissioned or sponsored by utilities.

Even this shortsighted, narrow approach reveals that it is more cost-effective for utilities and governments to support residential solar and community solar, as well as utility-provided solar than to maintain the status quo. Utilities themselves stand to benefit from increased solar installation, including residential solar, even with net metering.

A broader view would include a monetary value for the wider benefits to society, the economy, and the environment. This includes benefits for public health through cleaner air and water; a reduced need to invest in central power plants and massive distribution systems; and improved price stability and grid reliability over the longer term.

Residential solar is a clean, emission-free energy source. It reduces local and systemic carbon dioxide emissions and hazardous air pollutants including nitrogen oxide, mercury, and particulate matter that causes smog and soot. It also decreases upstream impacts of fossil fuel production and use, including fracking-related methane emissions, land destruction, water pollution, and even increased seismic activity (earthquakes).

Final thoughts on the environmental benefits of solar energy

There’s no doubt that solar power is a reliable form of renewable energy. It’s also increasingly accessible, for homeowners and renters, as well as businesses, non-profits, and government entities.

What are the advantages of going solar at home? In short, a solar electrical system could:

• Help reduce your energy bill
• Protect you from rising electricity prices
• Make you some money long-term
• Increase your property value by around 4%
• Give you backup power during blackouts and brownouts
• Pays for itself in eight years on average.

As for the environmental benefits of going solar, for homeowners these include:

• Cleaner, healthier air at home
• A lower carbon footprint.

Going solar is a great way to invest in a greener, more sustainable future. Your rooftop array, solar roof, solar shingles, or subscription to a community solar project can all inspire family, friends, colleagues, and neighbors to make greener choices. 

Solar electrical systems pay for their own energy use in less than two years and generate 3-25 times less greenhouse gas emissions than fossil fuels to produce the same amount of energy. They also reduce reliance on polluting fossil fuels, helping to improve air quality.

The sun provides the most abundant source of energy on Earth, delivering an impressive 173,000 terawatts of solar energy per second. Clearly, we can’t harvest all that energy, but even if we captured a fraction of it, we could power the world thousands of times over.

If more of the U.S. was powered by the sun, this would go a long way to helping tackle climate change and improving the nation’s health. Like any energy source, solar power isn’t perfect. There’s no question, though, that solar power has a net positive environmental and financial impact.