Residential Concentrated Solar Power Systems

The idea behind concentrated solar power systems(or CPV - concentrated photovoltaic) is to reduce the cost of solar power systems, measured in $ per Watt production capability. Solar panels are by far the largest cost item of residential solar power systems. The reason solar panels are relatively expensive is that most of the commercially available panels use silicon, and silicon is expensive.

Concentrated solar power is one method of cost reduction

The cost reduction efforts are mainly in three directions:

Using less expensive photovoltaic materials (polymers, thin film);

Using concentrated solar power systems (employing optic gear)

Increasing the production volume.

Less expensive photovoltaic do exist, however their conversion efficiency is not as good as the silicon conversion efficiency. As a result, the cost per square foot is indeed lower, however one needs bigger size panels to compensate for the lower efficiency; hence, the cost per Watt is not as we want it to be. As companies are working hard to develop these technologies, the expectation is that in the mid range future mass production of lower cost panels will be feasible
Concentrated Solar Photovoltaic(CPV) started as a technology for a utility size power plants and medium size enterprise systems. Recently, many start-up companies as well as incumbent companies are investing heavily into small CPV systems. It will take some more time to see which approach is the winning one and who are going to be the leaders and winners in the race. Down the road it is expected that field proven CPV residential systems will show up, at present it is a technology mostly used in medium size and large size facilities.

Background of CPV

The idea reminds me my childhood when I used a magnifying glass to ignite fire on a piece of paper by concentrating the sun radiation on the paper. According to the legend, Archimedes (287-212 BC) set fire on the Roman ships that were laying siege on his hometown Syracuse (Sicily). We all heard about fires in the woods caused by a broken glass. So, the idea is to collect by optical means sun radiation from a large area and concentrate it on a smaller size solar panel. Presumably, optics, be it a lens or a mirror, is cheaper than the silicon. Effectively, the optics virtually multiplies many times the size of the panel

Concentrated Photovoltaic Practical Issues

There are 2 practical issues involved

Concentrating a lot of sun radiation on a small area heats up the panel and reduces its effectiveness, so some way to remove heat is necessary
If the concentrating optics is not oriented accurately toward the sun the system will not receive sun radiation. The remedy is to add a solar tracker (with an unavoidable added cost and complexity)

One compromise is to use a crude concentrator that magnifies by 7-10 (rather than by hundreds) and is less susceptible to inaccuracies in pointing the optics toward the sun and its heat generation is more manageable

There are a dozen plus companies investing substantial money in developing CPV, about half a dozen in the Silicon Valley, at least two in Australia, at least one in Germany. Some of the companies have business affiliates in Spain

2011 Revisit of Concentrated Solar (CPV)

The number of CPV module manufacturers has grown from 47 to 54 since I wrote this page back in 2009. Some of the newbies are aiming to residential roof mounted CPV. The name of the game is cost reduction and practicality. The targeted niches are the commercial submarket and the residential sub-market. Both RFMD (Greensboro, N.C) and JDSU, well known veteran semiconductor manufacturers entered this promising area. JDSU specifically address CPV, and claim as features "a high degree of customization in cell size and configuration, state-of-the-art epitaxial growth, in-house characterization techniques."