Solar energy is used in power generation and its technology is advanced fast. If we compared the solar energy power generation efficiency with fossil fuels power generation the comparison will not be in the side of solar energy. However, you must put in your mind that solar energy is available and for free in opposite to fossil fuels that has high costs. In addition, solar energy power generation is clean and green power while the fossil fuels power generation is polluted and has environmental hazards.
Solar energy is used in power generation and its technology is advanced fast. If we compared the solar energy power generation efficiency with fossil fuels power generation the comparison will not be in the side of solar energy. However, you must put in your mind that solar energy is available and for free in opposite to fossil fuels that has high costs. In addition, solar energy power generation is clean and green power while the fossil fuels power generation is polluted and has environmental hazards.
Solar plant(farm), of few hundred kilo meter, in Sahara desert could supply the whole world, and is efficient too, main the initial investment. Germany, India etc. many countries have achieved around 50% of total power by solar power generation.
The conversion factor of ( power output ) / ( irradiance rate ) for a typical solar plant is not too great, if that is what you are referring to !
However, since the source energy (through irradiance) is for free, the conversion factor (which is roughly equivalent of efficiency in a conventional power plant) has "partial" importance in a solar thermal or PV power plants.
The free source energy is also what keeps the running cost of the plant substantially low - we don't actually "spend" on "input power" !
This feature of low running cost due to freely available source power is in fact, a characteristic feature of most energy sources that are classified as "renewables".
Consider you want to run a high voltage line (lets say for ex. 250 KV) from the Sahara desert to the USA, a distance of (for ex.) 8000 KM. The load is (for ex.) 1 Terawatt. What size cable do you need and what is the Vdrop? Not real practical at currently popular HV levels.