From the first energy saving light bulbs brought to the market in the mid-1980's, to the smart home thermostats and fixtures of today, what is the next step towards a self-sufficient, energy producing home? The golden goal for all homeowners and renters alike, is to lower energy bills without having to walk around our homes in10 layers of clothing when it's -3oC outside. We have double-glazed windows, porches, energy saving LED light bulbs, wall and loft insulation amongst other things in an attempt to save on our energy bills. Solar panels have been around for years too, but it's estimated that only half a million people in the UK alone actually have them installed for their homes. There are two main types of solar panel (or cell): photovoltaic solar panels (which convert the sun's energy to electricity, powering household goods and lighting) or thermal solar panels (which use the sun's energy to heat water, cutting down heating bills). What potential does solar power hold for the future of self-sufficient homes, and what new research is there for solar energy? Imagine windows which could generate electricity (\citet{futurity}). Too good to be true? Possibly not in the near future. Research suggests that transparent solar-film for windows could generate as much energy as bulky solar panels installed on roofs. By combining both rooftop solar panels and new solar-film, the electricity demand could be met for each country (including the UK and US), dramatically reducing fossil fuel use globally. But how do they work? It is not glass itself which acts as a solar panel. Instead it is an ultra-thin, transparent film which has been produced at Michigan State University by Professor Richard Lunt and his research team \cite{lunt2017}. The film has been coined 'a solar concentrator', and can be placed on windows, mobiles, buildings and other flat, clear surfaces to utilise the sun's energy without disrupting views. The film-like material is 'tuned' to absorb specific wavelengths of light (i.e. ultraviolet to near-infrared) and subsequently convert the light energy to electricity, just like a regular solar panel. Solar panels convert particles of light (i.e.photons) into electricity. They achieve this via the photoelectric effect: as photons come into contact with atoms in solar panels/film etc., they knock electrons out of atoms in a solar panel, creating a flow of electricity (i.e. a current). Traditionally, solar panels are made from lots of materials each required to generate a current. This forms an opaque object, yet solar-film is transparent and still performs the same job. Solar-film technology can increase the number of surfaces able to generate electricity all over the globe. Alongside this new research, Tesla has developed their own solar roofs. Instead of installing bulky solar panels, Tesla has developed solar cell roof tiles. This drastically increases the roof space which can be used to generate solar energy (\citet{tesla}). The tiles are not only able to generate solar energy for our homes, but are also a lot more durable than traditional roof tiles, able to withstand much greater forces (e.g. hailstones, high winds and fire). Another benefit of solar panels or solar roofs, is that they can earn you money. The amount of energy generated by solar panels, tiles or film is much greater than that which can be used in the home immediately. As a result, governments pay people who own these power supplies a set amount per unit of excess electricity generated and use it around the country. The sun's power is brilliant during daylight hours but at night where should we get electricity from? Tesla have developed another ingenious invention which can store some of the excess electricity generated during the day: the power wall (\citet{tesla}). The power wall is essentially a very large battery which can store some of the excess electricity, ideal for nighttime, natural disasters or blackouts. Once the battery is full, any more electricity generated will go to national use. It is an efficient way to use, store and share electricity.Currently, only 1.5% of the global electricity demand is met through the use of solar panels. If all windows in the US were covered in solar film, 40% of the electricity demand could be met. If all the roofs in the US were covered in solar panels or with Tesla's solar roof, this would equate to at least another 40%, taking the total to ~80% if both solar options were deployed. This is true Worldwide. These strategies would reduce the use of fossil fuels drastically and lower harmful carbon emissions tremendously. With stats like this, wouldn't it be great to get behind solar energy and all do our bit to better the future of the planet, creating self-sufficient homes?ContributionsLauren Nelson wrote the article. Lauren is a Ph.D. student at Newcastle University (UK), researching computational drug design alongside the Northern Institute for Cancer Research. Lauren also writes a scientific blog aiming to stop science from seeming so boring. (Twitter @ashortscientist; Instagram @ashortscientist; Blog: ashortscientist.wordpress.com).Ernesto Llamas made the illustrations. He obtained his Ph.D. in Biotechnology from Universitat de Barcelona doing his research at the Centre for Research in Agricultural Genomics. Creator, editor and illustrator of Sketching Science. (Instagram @eellamas).
