Man has been harnessing the sun’s energy for well over 2,500 years. He took advantage of the heat sink effect when building his homes into hillsides facing the sun. This provided heat well into the night as the earth slowly released the sun’s energy gained during the heat of the day.

In the 1880’s, the first selenium based photovoltaic cel was produced with a mere 1% – 2% efficiency. It wasn’t until the mid 1950’s when that figure rose to a more robust 11%. Solar power use didn’t really take off until the oil-embargo days of the 1970’s and enjoyed another growth spurt during the Gulf War, obviously spurred by the notion that oil was no longer going to be readily available. In that time, over 1,000,000 homes had a form of solar system installed.

Today, solar energy is harnessed in a variety of ways. The solutions become more numerous and efficient as the uncertainty of foreign energy reserves increases. A fortunate byproduct of that uncertainty is that as oil becomes more expensive and harder to obtain, solar power becomes less expensive due to the larger economies of scale in production of the panels and other infrastructures. This phoenomenon is not unlike the ever-improving cost vs. value relationship that computers have experienced over the past 20 years or so.

There has never been a greater focus on the potential of solar energy and it’s rightful place in our energy future. On a sunny day, the energy from the sun can produce the equivelant of 4,000 horsepower from just one acre of land. Once a system is installed, it is virtually maintenance free and should perform flawlessly for decades.

Concentrated Solar Thermal (CST)

Concentrated Solar Thermal systems produce energy by focusing the sun’s rays usually onto a pipe filled with a liquid heat transferring agent… typically water or a synthetic oil. This superheated liquid is pumped to a heat exchanger where the heat is used to produce steam which in turn, drives an electricity generating turbine.

Two variations on the CST theme are currently in use around the world. The more conventional type utilizes parabolic trough mirrors to focus the suns energy on a long pipe. These mirrors are mounted so they can track the sun through the sky during the day.

At the heart of the second CST variation is a large central tower housing a reservoir of fluid which is superheated by an enormous array of mirrors radially distributed in the field below. These mirrors also track the sun and deliver it’s energy to the top of the tower. The Power Tower as it’s called, in Seville, Spain was built in 2006 and is the first large scale implementation of this new and promising technology. The tower rises 40 stories above the mirror array and currently produces 11 MegaWatts of power with plans in place for this same facility to produce 300 MW by the end of 2013. Before you ask, no… this photo has not been Photoshopped. The amount of light focussed on the tower is so intense, it is almost impossible to look at it without sunglasses.

CST projects are generally utility scaled operations due to the relative higher capital cost and the requirement for concrete, steel and glass. Among the benefits of these projects is the fact that materials required to produce these projects are readily available. In other words, they don’t suffer from supply bottlenecks and subsequently offer investors a more secure investment.

Photovoltaics (PV)

Photovoltaic systems generate electricity when the energy from the photons in the sun’s rays displace electrons on semiconductor panels (usually made of silicon) producing an electrical current.

The Future

In response to mounting global pressures to advance the status of all forms of clean alternative energy sources, continued advancements in photovoltaic technoligies pave a road for exponential growth and security in the solar industry.

Nanotechnology holds significant potential to further improve the efficiencies of photovoltaics. Research underway is revealing that as much as ten times the light trapping capacity of conventional silicon based solar cells may be realized from the emerging nano technologies. Nano systems per unit cost should be a fraction of conventional systems’ because the organic polymer thin films require fewer and much less expensive materials.

… just so you know.

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