Although the traditional concentrators can reduce the amount of solar cell
they need high accurately tracking system. On the other hand
the spectrum of solar is very wide
while the absorbing spectrum of photovoltaic is narrow. So a lot of energy will be lost. In order to overcome these drawbacks
the later non-imaging optical system was studied. The concentrators with large accept angle and splitting characteristic was designed. This kind of concentrators can form high efficiency
non-tracing and portable PV modules
combined with solar cell. They can used as power of some special devices such as portable computer