Alternative energy sources - Solar energy


Solar radiation can be transformed into electricity thanks to the photoelectric effect. The photons of a light beam collide with the electrons of a certain surface, and thus eject the electrons, making them move freely -- in other words, turning them into electricity.

The efficiency factor of most current photovoltaics systems lies between 6 and 18%. It depends on the unit's design, the intensity of the solar radiation, the radiation angle, and the outside temperature. Conventional photovoltaics systems get less efficient at temperatures of 24° C and more. This is the reason why no giant photovoltaics farms can be built in hot, high-radiation areas such as deserts. The well-known solar power project in the Sahara is based on a different technology altogether: sunlight is harnessed to produce steam, which in turn drives the turbines that produce electricity. A further important efficiency-determining factor is the angle at which sun rays hit the photovoltaics panels -- a right angle is ideal.

By layering several different materials, it is possible today to construct panels that convert about 30% of the visible sunlight into electricity.

Types of solar cells

Thin film solar cells

Although silicon, which is needed to build solar cells, exists almost everywhere on Earth, production costs for photovoltaics plants are relatively high. In part, this is due to the fact that the manipulation of silicon requires cutting-edge technology that is very energy-intensive. As a consequence, silicon is an expensive material component of photovoltaics systems.

For increased efficiency, conventional photovoltaics plants today often include thin film technology. By depositing one or several very thin layers of photovoltaic material on glass substrate, a significant amount of silicon can be saved. While their efficiency factor is only 10% compared to conventional systems, due to their low production costs thin film plants are still an economical alternative. They are less suitable for large-scale applications such as power plants, but they are a good choice for other uses, such as panels mounted on house fronts.

Multijunction solar cells

Radiation moves at the speed of light and in the shape of particle waves -- similar to waves on the ocean. The light visible to humans constitutes only a fraction of the range of electromagnetic radiation. Apart from the light we can see, we are exposed at all times to other types of radiation that are invisible to us. Like the human eye, photovoltaics systems can only process a certain range of that radiation spectrum, which doesn't necessarily have to include optical light. If such as system combines several different materials, then it becomes possible to extract much more energy from solar radiation. Some multijunction systems can thus achieve an efficiency factor of 30% or more.

These systems are highly complex and very expensive to construct. They are an ideal choice for applications where the available solar radiation is subject to certain limitations, i.e., when a circumscribed, high-intensity space needs to be exploited in the most efficient way.

Organic solar cells

In building what is known as "plastic solar cells," organic photovoltaics (OPV) responds to the rising demand for flexible, thin, sturdy, and low-cost solar technology. To date, plastic solar cells have only reached an efficiency factor of around 2% -- a far lower rating than conventional, silicon-based cells. They are thus not suitable for photovoltaics plants or rooftop applications. However, they are projected to play a central role in powering consumer electronics such as cellular phones, laptops, GPS units, and so forth. For these purposes, the malleable plastic solar cells can be "woven" into the fabric of drapes, coats, blinds, windows, or walls. Moreover, they can be applied to various surfaces as a kind of "solar ink."

Organic photovoltaics technology is still in the development stage, so it isn't currently being used. By the time it is ready for the market, it should have achieved an efficiency factor between 5 and 10%, as well as a further reduction in production costs. Until then, a number of technical issues regarding the solar cells' stability and life span will have to be resolved.

Political and economic efficacy of photovoltaics

Current scientific research suggests that carbon dioxide, a by-product of combustion, has been contributing significantly to global warming. Moreover, it is generally acknowledged that global petroleum resources are dwindling, and will no longer suffice to supply energy for the world's population a few decades from now.

To increase the production of renewable energy would contribute to reducing carbon dioxide emissions, as well as the emission of other, even more toxic chemicals. In addition, it would help lower the world-wide consumption of fossil fuels (such as petroleum, coal, and gas).

Carinthia's focus on the development of photovoltaics technology will soon have a series of positive results. It will not only create jobs and generate value within the region, but it will also open up new possibilities for high-tech exports. Once we reach our goal of becoming an energy self-sufficient region, we will be able to minimize our dependency on fossil fuels.