Solar panels today rely on silicon to generate electricity from the sun. The technology has been around for nearly 50 years. Over the past half century, the cost of silicon solar cells has plunged nearly 98% since Jimmy Carter first installed solar panels on the roof of the White House.
Those original panels could only convert about 2% of the sunlight that struck them into electricity. Ordinary panels today have a conversion factor of around 20% with high end (and more expensive) panels able to convert almost 30% of sunlight to electricity. Alta Devices set the record for gallium arsenide solar cells last November with a 29.1% efficiency rating. Those cells are now being tested by NASA in space.
A totally different kind of solar cell was created by Japanese researchers in 2009. Called perovskite, it doesn’t depend on silicon. Instead, it uses a hybrid organic-inorganic lead or tin halide based material as the light harvesting active layer. According to TechCrunch, Oxford PV, a company based in the UK, is working on developing perovskite solar cells that could have a conversion rate as high as 37%.
What excites people about perovskites is they can be sprayed or painted on virtually any surface. The materials are abundant and inexpensive, which means solar panels using perovskite technology could cost half what conventional solar panels cost today. Instead of heavy and bulky mounting systems, perovskites could cover the surface area of buildings, vehicles, sidewalks, or vehicles, exponentially increasing the amount of sunlight hitting the Earth every day that gets converted to electricity.
Oxford PV recently got a cash infusion of $3 million from the UK government to continue its research. In the US last week, Swift Solar filed a statement with the Securities & Exchange Commission saying it has raised $7 million from investors to develop similar technology.
“Perovskite has let us truly rethink what we can do with the silicon-based solar panels we see on roofs today,” says Sam Stranks, one of the co-founders of Swift Solar. “Another aspect that really excites me: how cheaply these can be made. These thin crystalline films are made by mixing two inexpensive readily abundant salts to make an ink that can be deposited in many different ways. … This means that perovskite solar panels could cost less than half of their silicon counterparts.”
Oxford PV has already set a world record efficiency level for perovskite solar cells at 27.3% — 4% higher than the leading monocrystalline silicon panels available today. “Today, commercial-sized perovskite-on-silicon tandem solar cells are in production at our pilot line and we are optimizing equipment and processes in preparation for commercial deployment,” says Chris Case, the company’s chief technology officer.
It’s not all honey and roses for perovskites, however. They don’t currently have the durability of conventional solar panels and tend to degrade rather quickly in any environment outside the laboratory. It’s not that they can’t be made to compete head to head with silicon based solar cells, they just aren’t there yet. But then again, consider where electric cars were 10 years ago and where they are today. Progress seems to take forever until you wake up one morning and it seems like the world changed overnight.
Could perovskites be a key factor in converting the world to solar power? Yes. Will they be? “We’ll see,” said the Zen master.
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