Generating electricity from solar panels is currently the newest technology to get energy from renewable sources. One of the benefits for this method is that sunlight is free, so we don’t need to spend money and labor to mine coal or oil. The other benefit is that it won’t produce any greenhouse gases or pollution while generating the electricity.

However, building a solar power plant requires a large area, so most of the power plants are built in the desert. Some of the environmentalists are concerned about building power plants at the desert will destroy the fragile ecosystem, so that is why we haven’t really build many power plants now.

However, a study showed that we don’t need to build any power plants and we can produce 90% of the electricity we use in America. Let’s assume that there are 100 million houses and then each house installs a 100m2 solar panel on the roof, so there are total 100 billion m2. According to the research, there are 5 kwh per m2 per day of insolation to earth, and our recent solar panel can transfer 20% of the sunlight to electricity, so every m2 of solar panel can generate 1 kwh of electricity per day. So 100 billion m2 of solar panels can produce 3.65 trillion kwh of electricity per year.

And during 2005, America use about 4 trillion kwh. Although that not everyday and everywhere can have sunlight all the time, at least we can generate plenty of electricity by using solar panels and without using any lands.