The Photovoltaic (PV) market has always been an exciting one. The growth and new solar power technology developed has left even the biggest sceptic thinking twice about the opportunities that will arise and the goals that will be achieved by this amazing technology. In a world where Eskom has left us disappointed and in financial trouble time and time again, PV has been a way out of the sticky situations created by our utility provider. South Africa has adopted solar with such vigour primarily due to the country’s overburdened and monopolised energy infrastructure. And the innovation and development of this technology is a very exciting thing to observe and be a part of. In this article, I will look a bit closer at new PV technology and what could be possible in the future.
Less than 2% of the world’s electricity has come from solar power, but new inventions are likely to change that. SciShow, 2020.
You might think that vast, arid deserts are the perfect place to install solar farms. After all, desert sunlight is intense and you rarely have to worry about clouds. Plus, there is plenty of wide-open space. But there is one problem – solar panels don’t do well with heat. Solar panels work most efficiently at temperatures below 25°C. This is because when solar panels get hot, the electrons pick up that extra energy from their environment, which puts them in a more excited state. And when they are already excited, they have less room to absorb energy from the sun. They work best in moderate climates where, unfortunately, it can sometimes be hard to find the space to set up a giant field of solar panels.
But since the 2000s, countries around the world have been implementing what seems to be a win-win solution. A system called agrivoltaics. In agrivoltaics, solar panels get installed over crop fields. That way there is no need to clear extra space just for the panels. On top of that, the crops help keep things cool as they release water through their leaves. The release of water works just like sweating – evaporating water removes heat from a plant, which brings down the plant’s temperature and also cools the surrounding area. So they keep an optimal environment for panels to work noticeably more efficient.
Engineers have also expanded a similar concept to a setup called floatovoltaics in which floating solar panels are placed on bodies of water, which are also typically cooler than the air and help keep the panels cool and working efficiently. As a bonus, agrivoltaics and floatovoltaics also open up a lot of new possibilities when it comes to finding space for huge arrays of panels. The cost of maintaining the panels of a floating system is less expensive. This is because the water helps the panels remain dirt-free. In addition, water management of the lake or reservoir inadvertently becomes more cost-effective. The shade cast by the panels helps to significantly reduce excessive algae forming. The expanse of the floating solar panels drastically reduces the evaporation of the water.
Setups like these already exist all around the world, and they are becoming more popular. If that continues, agrivoltaics and floatovoltaics could produce a significant fraction of the world’s energy in the future.
Engineers are always striving to get as much energy out of solar panels as they possibly can. One thing they have to think about is the exact direction a panel should be facing. Solar panels produce the most energy when the sun’s rays are hitting them head-on rather than at an angle. Traditionally people have installed these panels at a fixed angle that gets the most direct sunlight at their specific latitude. But that’s not a perfect solution, because the angle of the sun’s light is always changing depending on the time of day and the season. That’s why engineers have created something called photovoltaic (PV) trackers.
These trackers move solar panels along tracks that follow the arc of the sun. The trackers make sure that the sun’s rays are always hitting the panels head-on so they are always performing at their peak. To run, these systems do use 5-10% of the energy they produce, but the energy gained outweigh those losses. These mounts can boost the amount of electricity a solar panel generates by up to 45%, depending on the geographic location. In places far from the equator, where the angle of sunlight varies significantly between summer and winter, PV trackers can be especially useful. They are generally still too heavy to be practical on a rooftop, which has to be structurally reinforced to carry something so heavy, but they are being used in other settings.
Most solar panels have a pretty conspicuous look, and they don’t just naturally blend into the surroundings or the architecture they are attached to. There is only so much you can do about that because the most common solar panels are made of silicon – a naturally bulky and heavy material. Silicon is great for turning light into electricity since its electrons are arranged in such a way that makes it easy for sunlight to know them loose, but it’s not the only option.
Some engineers are exploring alternatives, including solar cells that could be embedded right in your windows. Solar windows entail solar cells that would have to be made from something way lighter than silicon and also something partially transparent. Scientists did that by developing a new type of solar cell made of organic compounds. These organic solar cells are made of thin layers of materials like polymers and dyes that absorb light and turn it into electricity, a lot like silicon solar cells. They can be made by printing the dyes onto thin materials, like rolls of plastic or glass, in the case of windows.
By definition, a material that is absorbing light is usually pretty opaque, but organic solar cells can be designed to absorb mainly infrared light, letting visible light pass through. These days, organic solar cells are fairly transparent. They let through about 43% of light – which is pretty dark compared to the windows in your home, but they could make a nice tinted window for an office building. What’s great is cells like this are cheaper and easier to produce than silicon cells, and since they are so lightweight, they could eventually be adapted for phone screens, camping equipment, or car roofs. There is a small catch though, they are not nearly as efficient as silicon. They only convert about 13% of the sun’s energy into electricity, whereas silicon cells typically harness about 18-22%. Still, the fact that they are so easy to apply means that they could be installed in a greater number of places, including places that currently don’t generate any electricity.
In the future, buildings might not be the only things decked out in solar cells, because researchers are now working on solar fabrics. Textiles that would have solar cells integrated into the fibres. The end goal is to generate electricity just by walking outside. One method researchers are experimenting with is creating super tiny solar panels that can be embedded into fabric. In 2018, researchers in the UK created solar cells measuring 3mm x 1,5mm, basically the size of a flea. Then the tiny panels were embedded into yarn that was woven into clothing. The idea was for the panels to be small enough so that the person wearing the clothing shouldn’t feel them.
To test their invention, the researchers embedded 200 cells into a prototype and they were able to generate enough energy to charge a Fitbit. This is not a vast amount of energy, but with just 2 000 cells you could hook up your smartphone with a wire and make enough electricity to charge it. Not all solar fabric has to be wearable though. Other companies have successfully embedded solar cells into heavy textiles used for things like awnings and canopies, which have the benefit of sitting out in the sun all day long.
Battery recharging and range issues have been the Achilles heel of electric vehicles. Some automotive engineers believe solar power may be the solution. As solar becomes more efficient and compact, some electric vehicle companies have sought to incorporate panels into the roofs of their cars. Several start-ups, such as Aptera Motors, Atlis Motor Vehicles, Fisker Inc., Lightyear One and Sono Motors, as well as established OEMs like Hyundai, Tesla and Toyota, are developing solar cars or hybrid versions of them. They are integrating solar cells into roofs. However, other body parts, such as doors, hoods, tailgates and trunks, are also prime real estate. Some companies have taken it even further and will even make solar one of the main features of their car. For example, Aptera is releasing a car in 2021 that will utilise solar to give its driver an extra 65 kilometres of range a day!
New technology is being explored and invented every day in the photovoltaic market. Solar energy can easily provide substantial amounts of inexpensive, green electricity. Through new technology and continual improvement, solar photovoltaic cells are becoming even more versatile. New solar power technologies are demonstrating the versatility of this powerful energy source. It has never been more exciting to go solar.
Madelein Kroukamp's Portfolio 