I would like use the PV panel charge up a battery.In order to increase the efficiency, I would like to install some Fresnel lens above PV panel.It makes the light ways to concentrate on the PV panel in one point.But I am in doubt with some energy problem. Although the intensity of that point is increase much, the intensity of the area around the point will drop. Does it mean that the energy input with Fresnel lens is the same as that without the lens? If there is some difference, will the efficiency increase much?

Thanks.

One problem you may create using a lens is that the focus will heat up
more than the surrounding area. Depending on the current you are
trying to draw through the panel, this may cause problems with further
local heating of that area of the panel.

You could try searching for "effect solar PV shading" and have a trawl
through what comes up.

Shading is certainly a problem for many smaller roof and domestic PV
installations and what you are doing with a lens creates a similar
problem.

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Andy Fierman

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http://signality.co.uk
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With regards to the lens focusing the light you will not notice any real difference than if the panel was operating without a lens. When a PV panel is partly shaded (depending on the panel used) the output will not be as efficient than with no shading. Each panel has a number of cells wired in series and parallel, by shading one of the cells in series you will prevent it producing current, therefore blocking that entire 'string' of cells generating current.

Increasing the luminance on one area would mean that the other areas are effectively shaded, giving this problem of reduced output from the panel. also panels work best below 85 degrees centigrade, so dependant on the temperature created through the lens there could be efficiency problems in this regard too.

I hope this is of some use to you.