U. Brauch et al. [15] constructed a side pumping solar laser system to compare between different laser types. Nd:YAG and Nd:Cr:GSGG laser types were selected according to their laser and physical properties. This comparison indicated that solar pumped solid state lasers, especially the Nd:Cr:GSGG laser, are the best choice for space-power transmission, while depending on the conditions, Nd:YAG lasers may also be useful. They have demonstrated that the thermal problems, associated with high power CW solid state lasers can be reduced dramatically by cooling. Their experiments with direct solar pumped Nd:Cr:GSGG and Nd:YAG lasers at 77 K and 300 K showed that cooling the laser crystals to temperatures much lower than 300 K reduces thermal problems, increases efficiency and improves beam quality. They have also shown that the overall system efficiency can be increased by splitting the solar spectrum into different parts for conversion to laser power and to electrical power. The estimated values were 17 % for a laser/photovoltaic system and 27 % for a laser/solar dynamic system.