We always thought the world will look more like the Jetsons right now with flying cars and clean energy. While we’re still waiting on a flying car, or a jet pack, renewable energy, especially solar panels, have come a long way.
Solar panels are made of photovoltaic cells. These cells convert sunlight into energy by using photons to knock loose electrons. These cells are commonly made up of a silicon wafer-like sandwich. One wafer is positively charged, the other negative, this forms an electric field. Phosphorus is added to the top layer to raise the number of electrons there and boron is used for the bottom to make it more positive. Photons, from our buddy the sun, knock an electron out of that electrical field and then the cell has other parts that use that electron as energy.
Photovoltaic cells aren’t a new technology, they’ve been around for over a hundred years. The first “solar cell” was patented in the XIX century. But since then, it’s kind of been slow going. Almost 90 years later RCA Laboratories come out with the silicon adaptation of a solar cell … but it only had a performance of 1,1 %. Basically, that means for the amount of energy going into a solar cell from the sun, only 1,1% of that is transformed into usable electricity.
And research into solar technology is like we said, slow going. One researcher said gains of 0,3 percent are the norm and gains of 1 percent are seen as serious improvements. Since the 70s efficiency has only elevated from 1,1% to around 20% for most regular models. In contrast, traditional forms of electricity from fossil fuels are mainly about 40% efficient.
Over a decade ago the DARPA initiative put out a request for 50% efficiency in solar panels. So far, the quest has come close. In 2007 researchers from the University of Delaware declared they created a unit with 42,8 percent efficiency up from 40%, which in this field was a huge accomplishment. Their photovoltaic gained in efficiency by separating light into different energy bins of high, medium and low, and guide them onto cells of different light-sensitive materials to cover the solar spectrum.
And in 2014 Australian scientists announce a 40% efficient panel in the journal Progress in Photovoltaics. It pushed up efficiency by including another filter to grasp more bandwidths of light that are usually wasted by other units. But it’s still not either the typical model you’d see on houses. Most regular panels only get to an efficiency of around 20%.
Maybe silicon is not the answer.
Research into another material called perovskite has started over the past few years. Perovskite is a normally occurring mineral with a crystalline structure build out of calcium and titanium. It’s really easy to manufacture in a lab out of an organic-inorganic hybrid of lead, or tin halide that’s mixed with organic groups like methylammonium. The crystalline structure makes it distinctively good for such solar applications. But one of the exciting things about this new type of solar unit is how far it’s come in such a brief time. Perovskite research seems to be moving at very quick pace related to its counterpart, silicon. In only six years it jumped from 3,8% efficiency in 2009 to a confirmed 20,1% in 2015, which is a match for conventional silicon panels.
So, just maybe, they could reach DARPA’s goal in no time.
While perovskite panels aren’t on the market yet, some startups promise they’ll have some ready to go by 2017. One of the other great things about perovskite is that it is really cheap and easy to make. Which could be a blessing for those in areas without access to traditional sources of power.
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