why dont we harness solar enegy to the fullest?

Solar Cells are also horribly inefficient. Commercially viable solar cells are only about 16% efficient at best. Governments also tend to use what's most economical, and coal is very cheap, and one of China's main sources of energy.

we lack the technology to make solar cells efficient enough and cheap. todays best solar cells have an efficiency of only 25% and they are very expensive. A lot of silver is used to make these cells because silver is the best conductor of electricity and offers least resistance so to increase the efficiency of cells silver wires are used to connect one cell to the other, this increases the cost of the cell and the end result is a very expensive low efficiency cell. On the contrary if solar cells are used in space their efficiency and power generation is many times more then wats on earth so one way to generate electricity can be to use solar cells in space and then transmit the electricity to a particular place on earth through a microvave beam but yet again its a huge project ...

Hi, until the masses have electric cars and trucks, everything will depend on oil. Even if you want to set a solar installation somewhere, you will still have to use cars and or trucks to get the bits there. The entire manufacturing world uses cars, trucks and ships, nothing anywhere is made without using them somewhere along the line.