On Fri, 25 May 2012 13:18:22 +0100, The Natural Philosopher wrote:

A neighbour has had his roof adorned with panels and a nearby
tree
casts a large shadow across them, be interesting to see just how
much
that reduces the output..

It will reduce the output by lots. It only takes the shadow of a
few
twigs to really cut the performance. I cut a few trees back last
year
when I checked out what the effect was.

You only need to have a basic knowledge of photography to know that open
shade will give you 1/4 the light of full sun.

As will light cloud. Deep cloud reduces it anther 2-4 times, and you can
halve the output again within an hour of sunset.

But basic knowledge isn't your strong point, is it harry?

But it's not simply the amount of light being reduced the panels are
series connected and a shaded one reduces the terminal voltage and
possibly increases the source impedance so the panels that are fully
illuminated can't deliver their energy to the invertor.


--
Cheers
Dave.