I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that.
–Thomas Alva Edison
During the next decades, most of the traditional energy resources (oil, gas, uranium, coal) will reach the peak of their use. In addition, the use of energy will rise as a consequence of the rising standards of living in the still developing countries. Consequently, new alternative sources of energy must be researched and made profitable. One of the most important alternative energy sources is the solar energy.
The Sun ist the single largest energy source available to us, as it sends 970 trillion kWh worth of free energy to us every day. Furthermore, all the fossil fuels on Earth are product of organic life that drew its energy from the Sun. Hydropower and wind energy get depend on the sun, as well.
Concentrating Solar Power Devices
In the 19th century, concentrating solar power (CSP) devices using lenses or mirros to concentrate heat to drive engines or generators were designed. In the 1870s, CSP devices were used to drive steam engines. The first solar motor company was established a few decades later, in 1900.
Solar hot water systems are familiar to many people living in the warm and sunny countries. Solar water systems became popular in the 1970s, but unfortunately the systems on the roofs were both ugly and not very effective.
Today’s solar hot water equipment is much more efficient than the first generation was. In many areas in the USA, green building standards make the solar hot water equipment a required part of both residential and commercial construction.
Another common application of solar energy is photovoltaics (PV), in which photons are converted into electricity using semiconductors. The first photovoltaic chips were made as early as in 1883, using selenium and gold. The photovoltaic technology is by far the most important technology today.
Traditionally, PV cells are made from silicon. The process used for making them, is very expensive as the silicon must be refined to 99.9999 percent purity and baked in 1350 degrees centigrade. In addition, oxygen, moisture and airborne particles must be carefully controlled during the process.
Thin-film PV devices are the second generation of PV devices. These devices are based on mixture of elements applied in a thin layer to plastic or organic compontents. The thin film can be mass-produced for a fraction of the silicon PV chips, which has the potential to make solar energy cheap and cost effective enough to be used in the developing countries, as well.
Unfortunately, the thin-film solar is not as effective as the silicon cells. Most of the thin-films on the markets, have only a 4 to 5 percent efficiency. This is less than half of the efficiency provided by the silicon PV cells. The poor efficiency means that one needs to have twice as much surface are as when using PV cells.
Recent Trends in Photovoltaic R&D
The efficiency of thin-film PV is improving continuosly. In the research labs, efficiency of 19.5 percent has already been reached by Ascent Solar (NASDAQ: ASTI). Arise Technologies (TSX:APV) and SunPower (NASDAQ:SPWR), on the other hand, combine both silicon and thin-film PV wafers in a hybrid cell that boasts an efficiency of 18 percent.
Nanosolar is yet another interesting player trying to cut down the costs in PV production. It has developed technology for roll-printing the semiconductor of the solar cell with the help of a modified printing press. The ultimate goal is to produce building integrated photovoltaics, which integrate PV into the roofing materials. This would eliminate the need of separate solar panels entirely.
Yet another recent trend is designing hybrid photovoltaic/thermal (PV/T, PVT) elements. These combine layers of PV material with a thermal collector that both collects solar energy and increases the efficiency of PV layer by cooling it down.