Conditions such as temperature affect the performance of PV cells. That is one of the reasons some people install the panels to have some space between it and the roof. That way, there would be movement 9f air below the panel to cool it.

The use of MPPT charge controllers have helped users to harness the highest amount of energy from the PV panel at any time and from what i know, it has been proven to perform well.

Finally, i read that there are modifications going on to further increase the performance of PV cells, one of which is the use of nanotechnology.

A nice write up i must say.