CPower Srl Italy
The main obstacles for the photovoltaic energy to be competitive with standard energy sources are 3: the low efficiency, intended as low density of energy production for occupied area, the high cost of the constituting materials and the variability of the production which is correlated to the meteorological conditions.
While for the last point the solutions are related to technologies external to the PV, touching issues of grid management and distribution of solar plants, the first two issues are the aims of the PV research. One way investigated to improve the efficiency and reducing the costs is the concentrated photovoltaic (CPV); the light concentration allows higher efficiency for the cells’ PV conversion and permits to replace large part of photoactive materials with cheaper components concentrating the light. Unfortunately, besides these advantages some limitations are present for the CPV too; the most evident are the necessity for the panel to be mounted on a sun tracker and the capacity to convert only the direct component of the sunlight; moreover, the reliability of the CPV systems has not yet been proofed in field for long time as for the standard PV, since this technology has achieved an industrial dimension only in the last years. The photovoltaic concentrators spread on a large space of different possible configurations; there are concentrators with concentration factor from 2 to over 1000, there are CPV assemblies using silicon solar cells as well as using III-V semiconductors solar cells; there are CPV systems with one axis tracker as well as two axis tracker, and with different requirements on the pointing precision. All these different configurations have been developed from the first pioneer works in the ’70s till the current commercial products, to find the best solutions for cost competitive solar energy.
The CPV industry is very different from that of other PVs; indeed, a CPV module or assembly is made of many components requiring high precision of mounting. So, the CPV sector appears like an hybrid between the microelectronic and the automotive industries. This possibility to derive large part of the automation necessary for medium-high volume of production from other well consolidated industrial field is an important advantage for the first assessment of CPV and an useful reference for the cost analysis of large productions.