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Panel tilt on East facing "flat roof" - Page 2

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Posted by Dallas Dick/Jean Rystrom/Clay on April 16, 2010, 4:56 pm
 


An update: I had another Solar PV installer over and after going up on
the roof he determined that the roof was actually more like a 10
degree angle.  He also felt that there was no significant advantage in
increasing the angle of the modules to the east or south.  Part of his
reasoning is that tilting the individual panels would cause shading on
some of the panels unless they were spaced appropriately, in which
case we would be unable to put as many modules on the roof.  So the
gain from tilting would be lost by reducing the number of modules.
His recommendation is to lay the panels flat on the roof (on stand-
offs actually).
If the modules were tilted as a single unit the best angle we could
get is about 14 degrees.  I'm not sure that would help much.
Any thoughts?  BTW, thanks for the responses.

Posted by Dallas Dick/Jean Rystrom/Clay on April 16, 2010, 5:01 pm
 


An update: I had another Solar PV installer over and after going up on
the roof he determined that the roof was actually more like a 10
degree angle.  He also felt that there was no significant advantage in
increasing the angle of the modules to the east or south.  Part of his
reasoning is that tilting the individual panels would cause shading on
some of the panels unless they were spaced appropriately, in which
case we would be unable to put as many modules on the roof.  So the
gain from tilting would be lost by reducing the number of modules.
His recommendation is to lay the panels flat on the roof (on stand-
offs actually).
If the modules were tilted as a single unit the best angle we could
get is about 14 degrees.  I'm not sure that would help much.
Any thoughts?  BTW, thanks for the responses.

Posted by Josepi on April 16, 2010, 5:20 pm
 No comment on the angle but...

PV panels need to stay cool for efficiency and rain and snow need to run
underneath the panels. The standoffs are quite important for those saspects.

No way to turn them into awnings over some major south facing windows and
keep the solar radiant heat out in the summer months?




An update: I had another Solar PV installer over and after going up on
the roof he determined that the roof was actually more like a 10
degree angle.  He also felt that there was no significant advantage in
increasing the angle of the modules to the east or south.  Part of his
reasoning is that tilting the individual panels would cause shading on
some of the panels unless they were spaced appropriately, in which
case we would be unable to put as many modules on the roof.  So the
gain from tilting would be lost by reducing the number of modules.
His recommendation is to lay the panels flat on the roof (on stand-
offs actually).
If the modules were tilted as a single unit the best angle we could
get is about 14 degrees.  I'm not sure that would help much.
Any thoughts?  BTW, thanks for the responses.



Posted by Jean Marc on April 19, 2010, 8:46 am
 
message de news:
243ec913-fc82-4caa-b202-bc413f9aaa10@g10g2000yqh.googlegroups.com...

You could play with this tool:
http://re.jrc.ec.europa.eu/pvgis/apps/pvest.php?lang=en&map=europe

Don't know if there is a similar one for your part of the world, but still
could give you the gap from optimum.
Maybe there:
http://eosweb.larc.nasa.gov/cgi-bin/sse/sse.cgi?

HIH
JM



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