This article is one in a series of Instructables articles about DIY technology. The full list can be seen here.
Photo by Rob Patto from D.I.Y. Solar Setup
Step 1: Power Overwhelming
Solar panels collect their energy as the light hits the photovoltaic (PV) cells. The PV cells are semiconductors and when the light hits them electrons inside get knocked loose. If this happens enough times it can create a current of electrons moving in one direction. Combine that with the voltage of the PV cell and we get power. Not all of the light gets converted into power, however. Most solar panels are only 12% to 18% efficient.
The light that hits the PV cells is made up of different photons with different amounts of energy. To knock the electrons loose, the photon has to have the right amount of energy. Photons with too little or too much pass right on by. That’s 70% of the energy just moving right along while some other problems taking out a little bit more.
A disadvantage with the solar panels is the cost of production. Prices have been coming down, but are still an investment. In the United States, prices are around $4 per watt. Installing a 100-watt system, enough to power one 100-watt incandescent light bulb, would cost $400. At current electricity prices in California it would take well over a decade for the solar panel to start paying for itself.
Another problem with solar is where to put all of the panels. Energy is lost in transmission, which is why it’s great to put the panels on top of homes. It barely has anywhere to go, it’s the best commute ever. After that, solar installations take up a lot of space that then can’t be used for homes, parks, or anything else. And of course it needs to be installed somewhere where it will get a good amount of sunshine. All of this drastically limits the number of options.
With 18 terawatts being used globally, an increase of solar capacity to 2 terawatts would really move the needle. With the current solar technology that would mean installing 100 square meters of solar panels every second for the next 25 years. That would give us 67 billion square meters of solar panels. That would be nearly 26,000 square miles or a square 161 miles on a side. That’s over half the size of New York state. And then there would also be all of the infrastructure around the solar panels that would be needed to keep things running.
So are we all doomed to a non-solar future? Not quite. There can be some breakthrough in the technology, but it’s not something to place all of your faith in. If you’re concerned with your carbon footprint, then it would be worthwhile making your own life more efficient and consider how much energy your lifestyle uses. It’s a more difficult process, but it can be fun to see how you can change what’s right around you.
image below and more information from Saul Griffith's "The Game Plan"