[RE-wrenches] Troubleshooting Off-grid PV

[David Katz]

I would check each string.  I have seen many failed 120 watt Kyocera modules. They had a delamination problem.
David Katz

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----- Reply message -----
From: "Eric Stikes" <eric at harvesthesun.com>
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Subject: [RE-wrenches] Troubleshooting Off-grid PV
Date: Sun, May 27, 2012 2:51 pm



Hi Wrenches,

I inherited an off-grid PV system that seems to be significantly under producing. I have:

12 KC120's (~17V 7A each) paired up 2 in series, for 6 strings terminated on new 15A breakers in a new Midnite combiner,
Output of combiner passes through a 60A breaker then into a SolarBoost 50 charge controller. An SW4024 ties in the CC, a Kohler 8.5 Gen set, and a Yuasa 24V battery bank.

My problem is that I never see more than about 5A (displayed at charge controller) coming off the array, even in full sun, regardless of the state of charge of the batteries. I figure I should see, at least once in a while, closer to between 20-30A. Batteries are, admittedly, passed their life expectancy as the system was installed in '02 and I am sure this is part of the problem. I'm thinking that if the batteries are at about 1/2 capacity (don't own a hydrometer...yet), the controller senses the batteries are near full SOC even at lower voltage (~24V) and is therefore attempting to trickle charge even in the bulk stage. Though this is not how the CC is supposed to function in bulk, obviously, I'm assuming the old batteries are altering the standard operating conditions of the system. I've adjusted the Bulk set point on the CC but that doesn't seem to make a difference.

I doubt this is part of the problem but the generator is problematic as well (it has it's own array of maladies).

Any insight is greatly appreciated. Thanks!

--
Eric Stikes
Owner
SunHarvest Solar
+1 (530) 798 - 3738
www.harvesthesun.com<http://www.harvesthesun.com/>
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