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Panel Orientation with Batteries

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Posted by ~~NoMad~~ on January 12, 2007, 8:58 pm

It occurred to me that orientating solar panels tilted due south (180T) may
not be the best situation when charging batteries. It seems that it would be
best to charge the batteries as fast as possible in the early morning then
let the charge rate taper off during the latter part of the day. On
examination of a solar cycle chart it appears that an orientation of 120T
may be most effective to get batteries charged as soon as possible so that
they get a long tapered late afternoon finishing charge.

Are there any other considerations here?


Posted by dold on January 14, 2007, 8:33 pm

I am grid-tied with no batteries, so my interest is in most $ for the sun
that I get.  My optimum is 217 degrees.

An off-grid friend nearby thinks he should pattern his orientation after
his usage, which peaks in the morning.  He has freestanding racks that he
manually positioned with some portion toward the morning sun, and some
portion toward the afternoon sun.

He feels that he is optimizing "direct" use of the panels and easing the
usage of his batteries.

Clarence A Dold - Hidden Valley Lake, CA, USA  GPS: 38.8,-122.5

Posted by Solar Flare on January 15, 2007, 2:09 am
 I thought of this many times but some of the MPPT and inverters
consume power to be on standby or working. The varied angles would net
in a longer power consumption period before the MPPT shuts it's
circuits down.

Posted by dold on January 15, 2007, 8:46 pm
Would that be a matter of minutes?  Would the reduced peak wattage but
longer period offset that?  The power consumption is listed at 7 watts.

My Fronius starts when the sun is substantially behind the face of the
panels.  Late in the evening, I can see the flash of the panel backlight as
it tries to restart several times before it finally gives up, sometimes
when the sun is well below the local horizon.  

Clarence A Dold - Hidden Valley Lake, CA, USA  GPS: 38.8,-122.5

Posted by Solar Flare on January 16, 2007, 1:17 am
 Morning and afternoon orientation sounds like hours of extra
production. I am not sure what my unit draws on standby and when. When
it was on grid-tie it had to run the inverter and it was between 100W
and 150W depending on the load. Now it is running stndalone it has to
run all the time anyway.

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