Solar energy is one of the six alternative forms of power generation that gains increasing attention as nuclear fuels fall out of favor almost everywhere around the world today. 1% of renewable energy in the USA are generated with the sun at the moment, but scientists believe that eventually, the sun will be able to provide almost all energy needed on planet earth, once some of the technical hurdles that exist today are overcome.
For solar energy to be tranferred into electricity it needs a conversion system. The three common conversion systems for solar energy today are:
- Photovoltaic systems (PV, solar cells) that use semiconductor materials to capture the energy in the sunlight and directly convert it to electricity.
- Concentrating solar power systems that use solar heat to produce electricity by bundling sunlight with mirrors into a hot beam.
- Flat-plate collectors that heat water directly by exposing it to sunlight.
There may be new technologies coming up in years to come based on advantages on nanotechnology, but most of these ventures are experimental at best and nowhere near the scalable stage needed for satisfying broad demands. As often with renewable forms of energy, storage is a problem. This can be partly solved with molten salt storage: The heat from solar collectors is transferred to a network of tubes filles with a salt solution that contains the heat for several hours.
Advantages of solar power:
- No emission of greenhouse gases during operation.
- The sun is a free power source, so operating is extremely inexpensive.
Disadvantages of solar power:
- Solar energy plants can only generate electricity during daylight hours (about 5.5-8 hours).
- Solar energy is more expensive than other renewables, especially when compared with wind energy.
- Small overall contribution, because the technology is not advanced enough to compete with other, cheaper sources of energy.
- Limited tax credits in the USA, which creates weak incentives to invest in technology.
- Large footprint of thermal solar plants, only suitable for desert areas or uninhabited land, remote from actual demand.
- Photovoltaic is only useful for local application. The storage and transport problem is still unsolved.