In a mere 14 and a half seconds, the sun the sun provides as much energy to the earth as humanity uses in a single day. It only takes 88 minutes for the sun to deliver 470 exajoules of energy, which is the total amount of energy humans consume in an entire year. In less than five days, the sun can supply 36 zettajoules of energy – as much energy that is found in all proven reserves of oil, coal and natural gas in the world.
Even with the massive abundance of solar energy, solar power only makes up a minute fraction of all power generation capacity on the planet. Solar power accounts for about 0.2 percent of all energy production.
Solar energy has always been plentiful, but the means to capture it have been inefficient and expensive. However, that is quickly changing as the price of capturing solar energy has significantly dropped over the last 30 years.
Currently there is frequent talk of a “Moore’s law” in solar energy. Moore’s law states that the number of components that can be placed on a chip doubles every 18 months. In layman’s terms, the amount of computing power you can purchase for a dollar roughly doubles every 18 months. This has been happening for decades and is the reason the cell phone in your pocket has thousands of times as much memory as computers did decades ago and only costs tens or hundreds of dollars rather than millions. Now, if only this tactic worked in solar power technology. Then we would have extremely cheap, mass distributed energy technology that was much more effective than the giant and centralized technologies it was born from.
The National Renewable Energy Laboratory of the U.S. Department of Energy has seen the price per Watt of solar modules (not counting installation) plummet from $22 dollars in 1980 to under $3 today. The trend averages a 7 percent price reduction each year per watt of solar photovoltaic cells.
There are two factors behind the price changes. First, solar cell manufacturers are learning how to reduce the cost to fabricate solar.
Next, the efficiency of solar cells is constantly improving. In the lab, researches have achieved solar efficiencies of as high as 41 percent, which was unheard of 30 years ago. Inexpensive thin-film methods have increased laboratory efficiencies as high as 20 percent.
What do these trends predict for the future? If costs continue to decline 7 percent each year, then in 20 years the cost per watt of PV cells will be barely over 50 cents. Some feel the projections may actually be too conservative.
The cost of solar in the U.S. will cross the current average retail electricity price of 12 cents per kilowatt hour in around 2020. Since retail electricity prices rise by a few percent each year, prices will more than likely cross earlier.
By 2030, solar electricity is predicted to cost half of what coal electricity does today. Solar capacity is being constructed at a rapid pace already. Once prices become much more favorable than any other alternate energy source, the pace will only quicken.
The trend in solar watts per dollar has been occurring for at least 31 years. If it continues (which it most likely will) in another 8-10 years, we’ll have a power source that is as inexpensive as coal for electricity, with almost no carbon emissions. If the trend continues for 20 years, the world will have a green power source which is half the price of coal and electricity.