Solar makes financial sense for many households. But what are the environmental benefits of solar energy? Is solar really making a difference, individually and collectively?
The math and science say, pretty much indisputably, “yes.”
That being said, the question — and the answer — is worth examining from multiple angles.
Key Takeaway: Installing solar is an impactful sustainability move.
Solar panels have a carbon footprint and land use footprint just like any other manufactured product. But when its lifetime energy output is taken into account, solar energy is considerably better for the environment than energy derived from the burning of fossil fuels.
The clean energy potential and energy payback period of a residential solar system depend on the following:
While each solar system will vary, we’ll give you some numbers based on averages.
Carbon dioxide, or CO2, is one of the radiation-absorbing greenhouse gases that prevent heat from escaping Earth’s atmosphere.
As the primary greenhouse gas linked to recent climate change, carbon dioxide is generally the focus of mainstream discussions on renewable energy. But there are other greenhouse gases, too, including methane, nitrous oxide, ground-level ozone, water vapor, and F-gases (often used in aerosol propellants, pesticides, coolants, and other products).
Humans aren’t the only ones putting carbon dioxide into the atmosphere. Carbon is stored in many forms naturally, including in the ocean, sediments, rocks, and living organisms.
Many of the earth’s natural processes actually involve carbon output, including tree decomposition, forest fires, and volcanic eruptions. But nature has its own processes for keeping reservoirs of carbon dioxide balanced, including the role of forests in absorbing carbon dioxide.
However, the earth’s natural carbon cycle is disrupted by the large amounts of carbon — 30 billion tons per year — humans produce through various processes, including the following:
Basically, when we add large amounts of CO2 to the amounts nature is already producing, it overwhelms the natural systems in place. There is an imbalanced concentration of carbon in different reservoirs across the planet, creating an atmosphere where CO2 is effectively trapped. Greenhouse gases can remain in the atmosphere for anywhere from a few years to thousands of years.
The result? Higher average global temperatures and erratic weather patterns.
After conducting life cycle assessments of renewable and non-renewable energy sources, researchers published data in a 2017 Nature Energy study showing that solar generates 18 times less of a carbon footprint over its lifetime than coal and 13 times less of an emissions footprint than natural gas.
Consumer Ecology has drawn similar conclusions based on NREL lifecycle assessment data.
Consumer Ecology’s solar sustainability calculations put the carbon footprint of the average monocrystalline solar panel system is 25.8 kg CO2e per Megawatt Hour (MWh).
The carbon footprint of an equivalent amount of energy derived from natural gas is 486 g CO2e per kWh according to the NREL, which puts the greenhouse gas emissions of solar panels at 18.8 times lower than natural gas.
And these numbers aren’t just theoretical.
Brian Sheridan, development and engagement director of the Coalition for Clean Air, explains that there are concrete differences between solar-friendly states and less solar-friendly states in emissions numbers.
“If you zoom out a bit and look at the states that have set Renewable Portfolio Standards, in almost every case they've reduced emissions — mostly from the adoption of both residential and commercial solar.”
Read More: Why Does Your State Not Support Solar Power?
At an individual level, it can be eye-opening to reflect on our own households' impact on emissions levels.
In 2021, the average U.S. residential household used 10,632 kWh. Each kWh produces 0.855 pounds of carbon dioxide, so, on average, each household using the fossil fuel-powered utility grid is contributing more than 9,000 pounds of carbon emissions per year.
Hypothetically, if you installed a solar system that offsets 75 percent of your power from the grid, you’d avoid producing 200,000 pounds of carbon dioxide that you otherwise would over the lifetime of your system.
That’s a significant impact coming from your household alone, but when combined with a neighborhood of solar, or a city, or a state — the numbers are staggering.
This is the type of future many of us in the sustainability space are hoping to see: clean energy like solar producing close to 50 percent of the electricity in the United States in the 2050s.
One study even showed that converting all U.S. coal power plants to solar would save 52,000 American lives per year from reduced air pollution.
Not every solar aspect is perfectly green (even though it’s pretty darn close).
While solar has a zero-emissions output during use, there is an output of carbon emissions throughout a solar panel’s lifetime.
The solar cells in solar panels are made up of silicon and rare earth minerals like metals, which need to be mined. The process of mining silver, copper, indium, and tellurium produces greenhouse gas emissions and can also contaminate the areas impacted by mining, including the water, soil, and air. Lithium also needs to be mined for solar batteries.
The manufacturing process of solar components including panels, inverters, and batteries requires energy and thus produces emissions.
There are two types of crystalline solar cells: polycrystalline and monocrystalline. Polycrystalline solar cells are less common and involve melting silicon crystals together, requiring less energy to make.
Monocrystalline solar cells are more common due to their higher efficiency but they do produce more emissions than polycrystalline. To make monocrystalline cells, single pieces of silicon are cut into thin wafers and are then attached to the panel.
A third technology that is less common is thin-film solar, which incorporates amorphous silicon, cadmium telluride, or copper indium gallium selenide. Thin-film solar is relatively fast, easy, and more emissions-friendly to manufacture but the final product is not as efficient as monocrystalline or polycrystalline panels.
Again, the materials used in solar panels need to be either mined or produced, causing environmental impact in the process.
Since greenhouse gas emissions from transportation account for roughly 27 percent of total U.S. emissions — the highest single source of emissions — solar-related vehicle transport is crucial to this conversation.
Transportation emissions implications include the following factors:
For U.S. solar companies, a key solution in decarbonizing the supply chain is utilizing and expanding existing U.S.-based solar manufacturers to minimize reliance on overseas manufacturers.
The 2022 Inflation Reduction Act should help jumpstart growth in domestic solar manufacturing. The law includes about $369 billion in funding for various energy and climate measures including federal tax credits for solar manufacturers.
The Inflation Reduction Act also incentivizes electric vehicle (EV) adoption as well, another key decarbonizing effort to consider within transportation.
SunPower, in its Environmental, Social, and Governance (ESG) Report, has committed to converting 90 percent of its vehicle fleet to electric and hybrid vehicles by 2030 and has begun that process. SunPower’s initiative contributes to its plan to eventually achieve net zero carbon emissions for U.S. warehouse shipments to home delivery.
Hopefully, many other solar companies follow suit and take steps to decrease transportation-related emissions with electric and hybrid vehicles.
Read More: SunPower reviews
Solar panel recycling is much more expensive than putting them in a landfill, and there are no federal regulations mandating they be recycled. So it’s not too surprising that only about 10 percent of non-productive panels in the U.S. are recycled. Not a great look for a symbol of sustainability.
However, there is change happening in this realm as well. Solar company Sunrun and recycling company SOLARCYCLE can collaboratively recover up to 95 percent of a solar panel’s value through a process enabling the manufacturing of new panels or other materials.
EmPower Solar CEO David G. Schieren understands the full scope of the issues of solar and sustainability as the board president of the New York Solar Energy Industries Association (NYSEIA). He explains, “By recycling all parts of discarded solar panels, the industry could greatly offset the pollution caused by mining for new materials.”
Schieren adds that solar panel longevity is another consideration to the larger solution of minimizing waste — and therefore, consumers should invest in products that ensure longevity.
“SunPower panels, for example, operate at peak efficiency for 25 years, though they can last as long as 40 years,” Schieren says. “This reduces the need to produce more panels quickly, and demonstrates to manufacturers that the long lifespan of a product is just as important as its aesthetic value or energy efficiency.”
Read More: EmPower Solar reviews
While solar is generally installed on a rooftop, many commercial and community solar projects do have a land use footprint.
Citizen sustainability convert and "Switching to Electric" blogger Michael Jones covers solar topics in the larger context of the home electrification movement. He explains that progress is happening in the arena of solar land use, with solar canopies built over parking lots at shopping malls, colleges, sports stadia, and big box stores like Target and Walmart in the Southwestern United States.
“And there’s some interesting work being done at the intersection of solar and agriculture,” Jones shares. “In Massachusetts, cranberry growers are finding that their bogs perform perfectly well, even when solar panels are placed over them.”
Solar is a sustainable choice in general, regardless of the installation company used, so this information is fair game for solar companies to utilize in their marketing.
That being said, not all solar installers use environmental-based rhetoric — different approaches include appealing to financial benefits or increased energy independence.
We recently analyzed the home pages of our top-ranked 100 solar companies across all U.S. states to see how often companies are appealing to solar’s environmental benefits over motives related to finances or energy independence.
The verdict: We found that 53 percent of solar companies appeal to the sustainability benefits of solar with a pronounced call to action (CTA) or tagline on the home page.
Sustainability-themed taglines and CTAs included words like sustainable, green, environment, pure, clean, and renewable.
Meanwhile, companies are more likely to utilize financial savings messaging. We found that 74 percent of solar companies appeal to financial benefits with a pronounced CTA or tagline on the home page.
Financially charged taglines and CTAs included mention of tax incentives, money saved over a lifetime, or money saved monthly with solar.
Energy independence was not as prominent a theme as financial and environmental but was nonetheless utilized frequently. We found that 31 percent of solar companies appeal to the benefits of energy independence with a pronounced CTA or tagline on the home page.
Taglines and CTAs related to energy indepence mentioned emergency preparedness, the negatives of reliance on the grid, words like “independence” and “freedom,” and unfair utility policies.
Some companies utilized rhetoric relating to all three themes whereas, while rare, some didn’t mention any of them. In those cases, companies tended to feature a CTA related to their company’s awards, certifications, reviews, or other recognition setting them apart from other companies rather than attempting to convince the consumer of solar’s benefits overall.
What appears above the fold — or in this case, at the top of the page — is either a reflection of what the company deems important, or what the company thinks customers deem most important.
Messaging about the environment, financial benefits, and energy independence function to sell prospective customers on solar as an investment, regardless of the specific company they choose.
Read More: Is Solar Worth the Investment?
Still, one company’s emphasis on sustainability could potentially win over an environmentally minded consumer if they’re in the purchase stage. This brings us to our final consideration.
The majority of Americans care about sustainability.
A recent survey found that 65 percent of Americans say the U.S. government is doing “too little” to reduce the effects of climate change.
Another survey revealed that 66 percent of consumers are willing to pay more for sustainable products.
Customers have left over 30,000 reviews in Best Company’s solar category. Using a sample of those reviews, we identified the frequency of environmental keyword usage in positive reviews, including words and phrases like environment, sustainable, climate, fossil fuels, emissions, etc.
We found that 6 percent of 4-star and 5-star reviewers mention sustainability within their review, with comments like the following:
Customer Review: Ozzy
"Job well done, simple and easy. Makes sense to lower carbon impact and save money!"
Customer Review: Abner
“I am super pleased about the panels I have. Sunpower panels and Enphase Energy micro inverters are an unbeatable combination. I feel at ease knowing my panels are covered for any issues whatsoever as long as I own them. Feels good to be on the renewable energy bandwagon. :)”
We find that most reviews, in general, tend to focus on what a specific company has to offer as well as the overall customer experience, such as customer service, pricing, warranties, and value.
And yet, we find it notable that a small portion of reviewers took the time to share their experience with solar installation in the context of an investment in sustainability. Such could be said of any solar company, but these customers found it important enough to voice their satisfaction with solar’s environmental impact.
Solar technology has made huge strides in recent decades and will continue to improve in terms of minimizing land consumption, increasing solar cell efficiency, utilizing bifacial solar panels, and improving tracking systems that follow the sun for optimal energy production.
And consumers’ individual efforts don’t need to stop at solar installation.
Joshua M. Pearce, Ph.D., is the director of the Free Appropriate Sustainability Technology (FAST) Research Group and has led groundbreaking research in solar, recycling, and agricultural technology.
Pearce recommends consumers upsize their solar system to cover their thermal load with a heat pump and to cover the charging needs of their EV. “This can radically reduce their personal CO2 emissions,” he explains.
I was fascinated by images of less-polluted skies when commuting was at a low point during the pandemic in the spring of 2020.
Unfortunately, the temporary decrease in nitrogen dioxide emissions — a gas emitted by cars, planes, and power plants — during the height of the pandemic did little to slow humans’ excessive disruption of our planet’s carbon cycle.
It’s clear that the burgeoning residential solar industry, nurtured by government incentives and an increasing grassroots consumer demand for sustainable products and practices overall, is essential for minimizing carbon emissions in the short and long term.
Solar makes a difference. The question is — will we?
June 19th, 2023
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