June 6, 2011 - concentrating solar

Today, a quick look at concentrating solar power technology and its potential to power business and society.

When most people think about solar power, they picture solar photovoltaic panels: rectangular panels composed of a grid of individual solar PV cells, mounted perhaps on a building's roof or a nearby stand.  Photovoltaic cells convert solar energy into electricity, which flows through wires to power electric equipment.

Some people might also think of solar hot water panels, which function somewhat like a greenhouse and use solar energy to heat water circulating through a series of pipes or hoses.  The hot water can then be used for domestic hot water (perhaps after a secondary heating in a more traditional water heater) or for space heating.

Spread around houses or commercial buildings, these two solar energy conversion technologies - solar photovoltaics and solar thermal - have significant potential as distributed energy resources.

At the utility scale, it can be more cost-effective to concentrate the Sun's rays before converting the energy into a usable form, particularly if electricity is the desired end product.  In a concentrating solar application, a series of mirrors -- an array of either flat panels or trough-shaped parabolic mirrors -- can be used to concentrate the solar energy from a large surface area of the ground onto a relatively small area.  Concentrating solar technology works for both photovoltaics and for thermal systems.  In fact, given the larger amount of solar energy that is brought to bear through concentration, solar energy can be used to evaporate water into steam directly.  Concentrated solar energy can also be used to heat another medium, like molten sodium, which can in turn be used to evaporate water into steam.  The resulting steam can be used to spin turbine and generator sets to produce electricity.

Not all sites are well suited for concentrating solar, and today's technology continues to be refined through research and development.  The coming years may show whether photovoltaics or thermal installations prove more cost-effective.  For now, the race is on.