May 03, 2009
Two Companies Claim Cheaper Solar Concentrator Designs

Skyliine Solar uses parabolic mirrors to focus light on photovoltaic (PV) cells to generate electricity.

Skyline Solar, a startup that today announced its existence to the world, has developed a cheaper way to harvest energy from the sun. The company's solar panels concentrate sunlight onto a small area, reducing the amount of expensive semiconductor material needed to generate electricity.

Skyline Solar uses the parabolic trough approach used in solar thermal electric plants. They only concentrate the light by a factor of 10. Other companies pursuing photovoltaics (PV) with solar concentrators use much higher factors of light concentration and therefore have much bigger heat dissipation problems. The falling prices for PV reduces the advantage of using concentrators. The cheaper the PV the less point in using concentrators to reduce the amount of PV used.

Increases in PV efficiency help improve the economics of concentrating solar. If SunPower can improve their PV from 22% to 24% and beyond this will lower concentrating solar's costs because the same amount of mirrors will make more electricity. Higher efficiency PV fits well with concentrating solar. So concentrating solar with silicon-based high efficiency PV competes with thin film lower efficiency and lower cost PV.

An Israeli solar concentrator start up, Zenith Solar, is also claiming a cheaper way to do concentrated solar that uses both PV and thermal energy.

The technology, a system of rotating dishes made up of mirrors, is capable of harnessing up to 75 percent of incoming sunlight – roughly five times the capacity of traditional solar panels. In addition, using mirrors to reduce the number of photovoltaic cells needed, it makes the cost of solar energy roughly comparable to fossil fuels.

While this technology has been implemented elsewhere, Israeli start-up ZenithSolar – working in conjunction with Israel’s Ben-Gurion University – is a pioneer in combining it with a water-based cooling system that increases the photovoltaic cells’ efficiency and produces thermal energy to boot.

The value of that thermal energy depends on what you can do with it. Solar thermal's highest value comes in late winter and early spring when the days have gotten longer but the weather is still cold. The thermal energy can be used to heat buildings. But on a hot summer's day the hot water is only useful if it can boil and produce steam to generate electricity.

Do solar concentrators have a long range future? Or will declining PV prices make concentrators pointless?

Share |      Randall Parker, 2009 May 03 11:31 PM  Energy Solar

Doug said at May 4, 2009 11:33 AM:

The outcome seems to depend partly on whether the manufacturing costs of the various concentrators also come down.

Bruce Dunn said at May 6, 2009 11:06 AM:

If you want electricity and are content to have it only when the sun is shining (for example, to power air conditioners), then photovoltaic panels may eventually be cheapest. They are also the easiest to implement at the householder level.

However, for base load, grid connected electricity, solar thermal power has the advantage that is is relatively cheap to store thermal energy captured during the day (hot rocks, hot oil, phase change materials etc.) and make power after the sun has set. Storage efficiency is high as unlike most ways of trying to store electricity, there are no losses as energy is converted from one form to another.

billb said at August 12, 2009 6:03 AM:

Why can't the excess summertime thermal energy power an absorbtion unit to produce air conditioning? Why can't waste heat from an automobile engine do the same?

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