When solar thermal heat collection systems are factored in, total global solar energy capacity is a whopping 245 GW (2011), which exceeds that of wind energy (not by far, though), which is 238 GW (2011). Photovoltaic solar (these are the solar panels most people are accustomed to) capacity is a small fraction of that total solar amount. Photovoltaic is only 50 GW, while solar thermal accounts for the other 188 GW.
You have probably heard people argue about the fact that solar panels have a much lower power-to-size ratio than nuclear power plants, which can generate plenty of power with even one pellet of uranium.
Here is a more relevant argument: due to the fact that solar panels are the only generators that can be integrated into every shirt, knapsack, laptop, tablet, phone, roof, window, door, curtain, wall, car body, binder, watch, bridge, driveway, and even sidewalks; they can be set up to waste the least amount of land, even compared to nuclear power plants, which require the virtually permanent burial of toxic waste and can’t exactly be built on houses, carports, bags, etc.
This goes to show the paramount importance of how technologies are applied. Application is everything! (Not literally.)
There are two main solar thermal systems in use today:
1) Solar thermal power plants that generate electricity through the use of sunlight to boil water or mineral oil and produce steam, which then drives a steam turbine.
2) Solar thermal collectors that collect heat from sunlight and directly use it to heat water for showering, laundry, dishwashing, etc.
Both the solar and wind industries have exhibited strong growth for years, and according to an IEA (International Energy Agency) roadmap, solar could account for one-sixth of the world’s low-temperature heating and cooling needs by 2050.
Paolo Frankl, Head of IEA’s Renewable Energy Division, said: “Given that global energy demand for heat represents almost half of the world’s final energy use — more than the combined global demand for electricity and transport — solar heat can make a significant contribution in both tackling climate change and strengthening energy security.”
The IEA’s Solar Heating and Cooling Roadmap outlines how best to advance the global uptake of solar heating and cooling (SHC) technologies, which, it notes, involve very low levels of greenhouse-gas emissions. Some SHC technologies, such as domestic hot water heaters, are already widely in use in some countries, but others, like large-scale solar fired district heating, are just entering the wider deployment phase, while solar-powered cooling is still at the development stage.
The IEA roadmap also pointed out that there are industries which require large amounts of heat for their manufacturing processes, which could utilise solar thermal heat directly.