Traditionally, concentration has been proposed as a way of reducing the cost of photovoltaics (PV) [1]. As a rule of thumb, a higher concentration means lower costs. However, high and very high concentrations pose severe technological and economic limitations. For example, at very high concentrations the deleterious effect of series resistance can become important reducing the efficiency of the solar cell. However, suitable optical concentrators become rarer when the concentration increases and such properties as their acceptance angle are seriously affected. As well as this, efficient heat extraction could require complicated solutions. Therefore, the expected cost savings in reducing the solar cell area could be counterbalanced by the expensive cost of other elements such as sophisticated optics, a refined heat removal subsystem, etc or simply by the fact that, for a given concentration level, there is currently no available technology.