One of the most common objections to solar energy deployment is that the panels are “a blight on the landscape”, and to be fair there is some truth in that. Solar panels aren’t precisely pretty. They are black, dark green, or grey, mounted on large metal structures, and they don’t visually fit into the natural environment. No matter how much this type of criticism misses the point –renewable energy is fundamental to stopping climate change and this trumps individuals’ aesthetic sensibilities– researchers and companies have been working on ways to make panels more practical and also more visually pleasing.
The reasoning is that if there’s less of this ‘superficial’ opposition from people who care about solar panels’ appearance there will be less obstacles to overcome in getting projects approved and solar arrays built. The idea of transparent solar panels isn’t new, it’s been around for decades actually, but recent developments in material sciences have made the concept feasible for the first time. Up until now there have been many attempts at creating a transparent solar panel, and most of them have stumbled on two issues: the panels were never truly transparent, usually resembling thick tinted glass, and their yield was very poor compared to regular solar panels.
Luminescent solar concentrators
Now, researchers seem to have overcome this hurdle with the creation of what are called Luminescent Solar Concentrators (LSC’s). Instead of generating electricity from solar cells placed on an opaque surface, these panels are made of specially formulated transparent plastics which only block light from the ultraviolet and infrared spectrum. When hit with this type of light (which is present in sunlight) the plastic radiates it back out (essentially, it glows) and thin strips of solar cells that run along the external edges of the panel capture it and generate electricity using the same principle as regular solar panels.
All of this is possible because ultraviolet and infrared light are invisible to the human eye while the panels let 90% of visible light through, comparable to normal glass windows. Currently the panels’ efficiency is between 5% and 10% (meaning they transform between 5 and 10 percent of the light they receive into electricity), significantly less than normal solar panels, but this figure is predicted to grow as the technology becomes more refined. And this reduction in efficiency isn’t even a problem, because the technology will allow LSC’s to be placed in locations where traditional solar panels wouldn’t go, meaning any electricity they generate will be a net gain.
Perovskite solar cells
Another emerging technology are perovskite solar cells with graphene electrodes. Developed recently at Hong Kong Polytechnic University, these new solar cells are semi-transparent and have an efficiency of 12%, significantly higher than contemporary semi-transparent solar cells, which usually achieve figures of around 7%. Using graphene, a super thin form of carbon with very high conductivity, allows these cells to be translucent and to capture light from both sides. The other factor setting them apart from currently available technology is production cost. Both perovskite and graphene are very cheap, and the manufacturing costs of these cells are said to be significantly lower than comparable technologies.
According to the team that developed them they could be produced for as little as $0.50/Watt, which is even cheaper than current silicon cells. Up until now solar could only be deployed on rooftops or in fields outside urban environments, but with transparent and semi-transparent panels that look like normal glass the possibilities are endless. Entire skyscrapers could be covered in them, transforming their huge light-catching glass surfaces into energy generating resources. Another possible use case would be in self-charging smartphones and tablets; leaving your phone or tablet sitting in the sun would generate electricity to charge its battery. And what about electric vehicles? Cars and buses spend most of the time outdoors so covering their roofs with a layer of electricity-generating glass or plastic would help to recharge their batteries and reduce reliance on the electrical grid. Getting into a solar charging car in the middle of August might not be very pleasant, but if it significantly cut down on people’s electricity bills it would be worth it.
So far these technologies have seen very limited implementation, but their potential is enormous and when they reach the mainstream market they may very well change the landscape of our cities, our architecture, our electronic devices, and our vehicles.