When you imagine the energy of the future, solar power is probably in the picture. After all, it’s reliable, it is powerful, and it fuels the vast majority of life on earth. In recent years, less than two percent of the world’s electricity has come from solar power—but new inventions are likely to change that. So here are five ways solar energy could help power the future. You might think that vast, arid deserts are the perfect place to install solar farms. After all, desert sunlight is intense, and you don’t usually have to worry about clouds.
There’s plenty of wide-open space. But there is one problem: Solar panels aren’t fans of heat. Solar panels work by converting light directly into electricity: When they absorb sunlight, that energy knocks electrons loose and those loose electrons create an electrical current, which can be captured and transferred to awareness. The thing is, solar panels do that most efficiently at temperatures under 25 degrees Celsius. That’s because, when the solar panels get hot, the electrons pick up that extra energy from their environment, which puts them in a more excited state.
When they’re already excited, they have less room to absorb energy from the Sun. So, they actually 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’s no need to clear extra space just for the panels, and, on top of that.
The crops help keep things cool as they release water through their leaves. That 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 it can help keep things nice and balmy for the solar panels. And it makes them noticeably more efficient! Researchers centered at the University of Arizona found that, between May and July of 2019, solar panelsover croplands were three percent more efficient than solar panels in the same region that was not over croplands.
That might not sound like a lot, but over time, those small gains add up. For a house or building operating on solar power, it would amount to close to three days’ worth of electricity over those three months. Engineers have also extended a similar concept to a setup called photovoltaics, 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 an added bonus, agrivoltaics and floatovoltaicsalso open up lots of new possibilities when it comes to finding space for huge arrays of panels.
Setups like these already exist all around the world, and they’re becoming more popular. If that continues, agrivoltaics and floatovoltaicscould produce a significant fraction of the world’s energy in the future. Engineers are always trying to get as much energy out of solar panels as they possibly can. And one of the things they have to think about is exactly what direction a panel should be facing. See, 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 invented something called photovoltaic trackers or PV trackers. PV 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’re always performing at their peak.
To run, these systems do use about 5 to 10percent of the energy they produce, but the energy gained outweighs those losses. In fact, these mounts can boost the amount of electricity a solar panel generates by up to 45 percent, depending on the geographic location. In places far from the equator, where the angle of sunlight varies significantly between summer and winter, PVtrackers can be especially useful. They’re generally still too heavy to be practical on rooftops, which have 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 their surroundings or the architecture they’re attached to. But there’s only so much you can do about that because the most common solar panels are made of silicon, which is just naturally bulky and heavy. Silicon is great for turning light energy into electricity —since its electrons are arranged in a way that makes it easy for sunlight to knock 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. Like, the idea is that you could be sitting by a window on a sunny day, and there are light and warmth hitting you. But some of that sunlight could also be converted into electrical energy right in the glass. But for that to happen, solar cells would need to be made of something way lighter than silicon and also something partially transparent. Scientists actually found a way to do 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. But they can be made by printing the dyes onto thin materials, like rolls of plastic—or glass, in the case of windows. Now, by definition, a material that’s absorbing light is usually pretty opaque, but organic solar cells can be designed to absorb mainly infrared light, letting visible light pass through. So, these days, organic solar cells are fairly transparent.
They let through about 43 percent 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 that cells like this are cheaper and easier to produce than silicon cells, and since they’re so lightweight, they could eventually be adapted for phone screens, camping equipment, or carrots. There is a small catch: They’re not nearly as efficient as silicon. They only convert about 13 percent of the sun’s energy into electricity, whereas silicon cells typically harness about 18 to 22 percent.
The fact that they’re so easy to apply means they could be installed in a greater number of places —including places that don’t currently generate any electricity. In the future, buildings might not be the only things decked out in solar cells—because now, researchers are working on solar fabrics, textiles that would have solar cells integrated into the fibers. The end goal is to generate electricity just by walking outside. One method researchers are experimenting with creating super-tiny solar panels that can be embedded into the fabric.
In 2018, researchers in the U.K. created solar cells measuring 3 millimeters by 1.5 millimeters—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 that the person wearing the clothing shouldn’tfeel them. To test their invention, the researchers embedded200 cells in a prototype—and they were able to generate enough energy to charge a Fitbit. So we’re not talking like a huge amount of energy here.
With just 2000 cells, you could hook up your smartphone with a wire and make enough electricity to charge it. Believe it or not, the design is actually pretty subtle, too. Other fashion designers have incorporated solar panels into fabric in the past, but they’re usually pretty noticeable… which tends to turn people off. Unless you want to put on like a cool mask and really awesome jeans and then rollerblade like it’s cyberpunktimes. 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 actually sitting out in the sun all day long, too. Finally, most recent inventions related to solar energy have focused on creating electrical energy, but some researchers have taken a different approach: They’re focusing on using the Sun’s energy for thermal power, the kind of thing that heats our homes. The goal is to create a rechargeable battery made of chemicals called solar thermal fuels.
Solar thermal fuels absorb the Sun’s energy, store it in chemical bonds, and then release it as heat at a later time. And they can do that on command. When these fuels absorb sunlight, that new energy disrupts the chemical bonds in the molecules and causes them to rearrange into a new configuration. Now it always takes energy for molecules to form chemical bonds with each other, and this new configuration takes more energy —so it traps all the energy the fuel has absorbed from the Sun and just holds onto it.
Like, researchers in Sweden developed a fuel that can store solar energy for nearly two decades. But, as soon as you want that energy back, you can pass those molecules through a physical filter that acts as a catalyst to rearrange those molecules back into their original configuration—and release all that pent-up energy as heat. In fact, the team in Sweden got the fuel to bump the temperature of its immediate surroundings by 63 degrees in just a few minutes. And the team is hoping to get that number even higher.