Re: Re: Solar PV

[Simon H <silvertringbongo@xxxxxxxxxxx>]

My first question posted on this forum after many years: be gentle
with me!

My solar PV was installed last week, and consists of 16 off Sanyo HIT
250W panels, in two strings (12 and 4).  The inverter is an Aurora 3600
(3.6KW) which was specified due to the separate strings, but I
understand to be a very good unit.  A small amount of chimney shading
during a small part of the day was factored into the design, hence part
of the reason for two strings.

Thus far I am happy, and have seen 4014W once or twice indicated under
optimal conditions.  Oh how the Aurora hums!

However, I have seen one thing I have had cause to question:  since I
cannot peel my eyes away from the inverter readout I noticed the main
array output drop to 500W, when the smaller array was managing 1024W.  I
rushed out to see that the chimney was shading a small part of one panel
on the main array.  This effect lasted a few minutes and then passed.

Conclusion was that shading affects output far more than I imagined, and
caused me to question why the strings had been designed in that
configuration.  Surely the design should make the smaller string the one
most affected?  Answer from the installer: it's the way the software
spits it out and we are often surprised ourselves.

I don't find this satisfactory.  As the angle of incidence changes over
the year, shading will become more of a factor.  The installer has
stated that to change this will mean more scaffolding and panels off to
change the cable layout.  There was me thinking they could just chop and
join the cables in the loft space.  On that point, they were going to
use 4mm cables throughout, but based on what I have read here, I
persuaded them to use 6mm.

I can only monitor the output for now to see what's what, but I am also
nervous about forcing them into changing the layout only to find they
were right all along!  Can you see my dilemma?

Thoughts, comments, and suggestions welcome.

Cheers,

Simon H



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