Solar Energy-Electrical Energy Conversion

Power energy belongs to high-grade energy, which is convenient in utilization, transition and distribution. How to convert solar energy into power energy has been the crucial technologies foundation for large-scale utilization of solar energy, which has been, raised attentions from each country in the world. It can be realized in many conversion channels, i.e. direct conversion of solar energy into power energy and indirect conversion of solar energy into power energy. Solar cells, the direct conversion apparatus is to be focused on this paper.

Report on silicon solar cells was firstly launched in the worldwide in 1941. Single crystal silicon solar cells with the efficiency of 6% were developed successfully in 1954. The solar cells were firstly applied to generating electricity to satellites in 1958.

Before 1070s, the solar cells were mainly applied to space utilization due to its low efficiency and expensive price. After 1970s, extensive research was conducted on its material, structure and process. Great progress was achieved in increasing efficiency and reducing cost. The utilization in the ground was also expanding gradually. But comparing with the conventional power system, the cost was still expensive for the mass-scale utilization of solar energy.

Right now, the highest level of experimental efficiency of solar cells in the world is:

a.        For single crystal silicon solar cells, 24%(4cm²)

b.        For multi crystal silicon solar cells, 18.6%(4cm²)

c.        For InGaP/GaAs twin-structured solar cells, 30.28%(AM1)

d.        For non crystal silicon solar cells, 24%(initially), 12.8%(steady)

e.        For telluride cadmium solar cells, 15.8%

f.        For silicon ribbon cells, 14.6%

g.        For titanium dioxide nanometer organic cells, 10.96%

In China, research on solar cells was started on 1958. Results have been achieved for 40 years. Right now, the highest level of experimental efficiency of solar cells is:

a.       For single crystal silicon solar cells, 20.4%(2cm´2cm)

b.        For multi crystal silicon solar cells, 14.5%(2cm´2cm), 12%(10cm´10cm)

c.        For GaAs solar cells, 20.1%(1cm´1cm)

d.        For GaAs/Ge cells, 19.5%(AM0)

e.        For CuInSe cells, 9%(1cm´1cm)

f.        For multi crystal silicon thin film cells, 13.6%(1cm´1cm, non activated silicon liner)

g.        For non crystal silicon cells, 8.6%(10cm´10cm), 7.9%(20cm´20cm), 6.2%(30cm´30cm)

h.        For titanium dioxide nanometer organic cells, 10%(1cm´1cm)