Like batteries, automobiles, nuclear power plants, and well, basically everything, solar panels have a lifespan. The “renewable” in renewable energy refers to the fuel inputs. For example, coal and petroleum are fuel inputs not the infrastructure and physical devices to capture energy. Uranium is the input for nukes. Now, the sun isn’t going to flame out for a few billion years. Phew! During that time, wind will continue to move air and spin wind turbines. The oceans will still make waves (thanks to wind and the moon). But harnessing these forms of energy generation requires material components that wear out. In this blog, we’ll focus on PV panel efficiency, their lifespan, and how to recycle a solar panel.
Solar power takes two forms. Today, we’ll discuss the obvious one: photovoltaic energy transformed to electricity. The other form is heat power. For example, using the sun to heat water or concentrating mirrored dishes to cook food like in a solar oven.
Panels lose efficiency over time. The average lifespan is about 25-30 years with a loss of up to 20% efficiency in that period. However, most panels only show efficiency decrease of less than 10% in 25 years of daily use. High quality panels can function up to 40 years in some cases.
But every panel loses its production over time. Opportunities await those who reclaim castoff components. That’s why PV recycling is a growing market.
A Brief Solar History and the development of Cell Efficiency
First, let’s look at the history of solar power. Using the sun to produce electric power dates back over 150 years.
In 1839, French electrolytic cells generated a tiny current. At the age of 19, Edmond Becquerel, a physicist working in his father’s lab, generated the first PV effect. Today, a prize named in his honor is awarded annually at the European PV Solar Energy Conference by the European Commission.
In 1883, Charles Fritts developed a selenium cell solar panel. A year later, he installed an array on a rooftop in New York. The efficiency rating was less than 1%!
Albert Einstein described the photoelectric effect at a quantum level in a paper published in 1905. Over 15 years later, the research (and other work on theoretical physics) earned him a Nobel Prize in Physics.
In 1954, Bell Labs produced a silicon solar cell with an efficiency of 6%. A year later, they made a commercial cell with a 2% efficiency that cost about $1,785/watt. For comparison, today’s solar cells cost about $0.30 per watt (before installation).
By 1959, Hoffman Electronics made a 10% efficient commercial cell. A year later, they’d improved efficiency to 14%.
The first piloted spacecraft powered by solar energy was the Soyuz 1, in 1967.
In 1977, global production of PV cells exceeded 500 kilowatts or 0.5 megawatts. Global solar installation power reached 1,000 megawatts IN 1999. Remember, a kw is 1/1,000 of a megawatt. In 20 years, solar power output increased by 2,000 times over!
By 2008, a new record in efficiency was achieved. The US Dept. of Energy National Renewable Energy Lab (NREL) built a cell with almost 41% efficiency. However, they focused the energy equivalent of over 300 suns at the device to break the old record.
First Solar used cadmium telluride (CdTe) cells to convert 22% efficiency in 2016. Today, about 5% of the global solar market uses CdTe technology.
NREL set another record using multi-junction solar concentrator solar cells in 2019. They measured 47% efficiency.
In 2020, scientists added a layer of perovskite crystals to boost efficiency in solar panels. The breakthrough reduces the cost of producing electricity.
Solar waste map
Created by GreenMatch
Solar panel recycling
Why do we need PV recycling? Depending on the conditions (like climate) and quality, solar panels lose efficiency. After 20-40 years, they’re replaced. Without recycling programs, an estimated 60-80 million tons of solar panels will end up in landfills by 2050. That’s not exactly “clean” energy.
Fortunately, some enterprising recyclers are stepping up to meet the challenge. This is an intense and industry-specific recycling process. It’s not like putting out your aluminum cans and bottles for curbside pickup.
How to recycle a solar panel
We’ll discuss silicon-based solar panel recycling. Keep in mind, thin-film based cells are also recyclable, but the process is different. Up to 96% of a panel can be reclaimed, but that number is increasing.
A solar panel is like a silicon sandwich, laminated under thin sheets of plastic. A stiff metal frame protects the fragile glass layers.
In recycling, the junction box and wiring (mostly aluminum and copper) are stripped off a panel. First, the recycler separates metal and glass parts. The rest is shredded.
Basically, almost every bit of glass is reused, about 95%. External metal (frames) can make new cell frames.
The internal silicon wafers and metal contacts (busbars, conductors and wiring), are heated at high temps to loosen the bindings. The silver electrodes, tin, and lead connections are lost in the mix.
Extracting and separating silicon and silver is difficult but some recyclers are doing it with an optical process. Most recyclers crush bits together as a “dirty” source of glass.
Where can you recycle panels?
In the EU, solar producers must plan for end-of-life recycling. In some countries, like Japan, Australia, and India, solar recycling laws are in process.
There are no US solar recycling mandates in place, except for Washington state. Washington passed its product stewardship bill in 2017 as part of a Solar Incentives Job Bill.
In 2021, California changed solar panel designation from hazardous waste to universal waste in an effort to increase recycling efforts. The new rule makes it easier to collect, process, and recycle solar panels that are past their prime.
Otherwise, PV recycling in the US is voluntary and therefore limited.
One Nevada company, Recycle PV Solar, captures 90% of solar panels they accept from all over the US. They reclaim raw materials, mostly glass and aluminum. They repurpose old solar panels. The company places intact panels in off-grid installations or where they can bear lower efficiency rates.