How do we make solar energy cheaper than conventional energy sources that we use? how will we increase the efficiency of a cell to maximum?

To make solar energy cheaper we have a lot ways >> the most important two of them are:1- increasing local manufacturing part of solar energy components 

2- develop encouraging customs laws and schemes to lower initial costsIncreasing the cell efficiency is depending on type of solar cell but in general increasing light collection efficiceny is very important 

A cell's efficiency can be increased by - minimizing the amount of light reflected away from the cell's surface. - use the best angle - use mppt - tracking system

i think the solar tracking system is so awesome way to solve these problems.

to introduce solar tracking system into our traditional syatem

Conventional energy sources are avaliable in huge amount in earth crust and more efficient  than non-conventional sources.That is the reason we use conventional sources for power generation.

Solar energy is very useful and renewable source,but the materials use for making PV Cell is expensive.But the solar companies try to make it cheaper.

Highest efficiency of the cell is achieved which is44% by Helmholtz Center Berlin.Different elements research and their properties,and many factors that includes in the efficiency of the cell.