Every day, the sands of the Sahara Desert reach temperatures up to 80° Celsius. Stretching over roughly nine million square kilometers, this massive desert receives about  22 million terawatt hours of energy from the Sun every year. That’s well over 100 times more energy  than humanity consumes annually. So, could covering the desert with solar  panels solve our energy problems for good? Solar panels work when light particles hit their surface with enough energy to knock electrons  out of their stable bonds. On their journey back to stability,  these electrons produce electricity. However, there’s a limit to how much power panels can generate. Solar panels can only interact  with certain wavelengths of light, making it impossible to convert  over half the sunlight they receive. And even light particles they can convert often bounce off them without ever hitting an electron. But thanks to clever scientists  and engineers and substantial government investment, solar panels are generating  more electricity than ever. Anti-reflective coatings and patterns  on the panels’ surface create more opportunities for incoming  light particles to hit electrons. These techniques have increased commercial solar panel efficiency from the low-teens to 25%, with experimental models reaching up to 47%. What’s more, solar has gotten  89% cheaper over the last decade, thanks in part to global supply chains for other technologies that use the same materials. Together, these factors have  made solar power the cheapest source of electricity  on Earth. Countries including India, China,  Egypt, and the US, have already taken these new panels into the desert. Their massive solar farms range  from 15 to 56 square kilometers, and when the sun is high in the sky, these plants can provide energy for hundreds of thousands of local residents. But these farms also get extremely hot. Light that solar cells don’t convert  or reflect is absorbed as heat, which reduces a panel’s efficiency. And the cooling systems employed by many farms can use huge amounts of energy powering fans or moving water  to maintain optimal temperatures. Even with these systems, solar panels  in the desert absorb far more heat than the natural sandy environment. This hasn’t been a problem on the scale of existing solar farms. But if we tried to cover the Sahara, this effect could create massive changes in the region's climate. Constructing solar farms already disrupts local ecosystems, but a plant of this scale could  dramatically transform the desert landscape. Thankfully, solar panels aren’t our only option. And some of the largest solar plants  in the world are trying a new approach: giant mirrors. Morocco’s Noor Power Plant, which will eventually cover roughly  30 square kilometers of the Sahara, is a concentrated solar power plant. This design reflects light  onto a receiver, which converts that energy to heat, and then electricity. These mirrors still create a dangerous temperature shift for local wildlife, but they have less potential to transform the landscape. And since it takes time for the materials being heated to cool off, these plants often continue producing electricity past sunset. Whether they use panels or mirrors, industrial solar farms are often easy to fit into existing energy infrastructure. However, getting their electricity beyond local power grids is much more difficult. Some countries are working on ways to connect electric grids across the globe. And many farm store energy in massive batteries, or convert their electricity  into clean gas that can be used later. But right now, these techniques are still too expensive and inefficient to rely on. Worse still, industrial renewables can share some of the same problems as fossil fuels, relying on destructive mining operations  and carbon-emitting global supply chains. Fortunately, solar can exist on many scales, from industrial solar farms  to smaller installations that power individual buildings  and rural communities. These projects can supplement energy use or provide a passive source of energy for regions off the grid. And since solar panels rely  on a few simple components, they’re quick to install  and relatively easy to update. In fact, it’s this flexibility  that enabled solar to become so cheap and ubiquitous  over the last decade. So if we want to keep up with humanity's rising energy use, we'll need answers both big and small.