Solar Mirror Revelation!

I have always wondered why people never put a couple of mirrors above
and below the solar cells. After all the Photo voltaic solar cells
are quite expensive per square meter. If the cost of reflective film
is cheap so why not improve the peak power output by using some cheap
mirrors ?

My musings have now been answered.

If the sunlight falls disproportionately onto a solar cell (parts
brighter than others) then the parts change their impedance. This
makes some parts of the cell absorb electricity while others
generate. You can get hot spots which then make the material 'brake
down'. This can damage the PV cell.

All explained at
http://www.redrok.com/up980301.htm

Practical Photovoltaics apparently explains why and introduces some
electronics to sort it out too.

You would think that the space people for whom cost is no problem but
weight is would see the advantages of having a double/triple the
power for no practically no increase in mass.

You can see why a thermal panel would benefit little from the use of
mirrors. The increase in heat would come at the hot point in the year
and the decrease ( in non direct sunlight ) would come at the lowest
point. If you where storing energy over the year ( few Danish systems
do system store ) then the over production in the summer is a
different matter.

still mystery solved.