I'd echo Bob-O on this and also add that when diagnosing others' work
over the phone, it often is completely different issues when you get
there. You have no idea if for instance he's actually got the modules
wired correctly, he may have a loose connection(s) there, the parallels
may all be loaded onto one 12 ga wire out, and cooking a module jbox
connection, etc.
The DIYers never want to hear it, but its always time for a rewire, and
a bigger controller too. It's the only way I take these systems on: all
or nothing.
Once they're suffered for long enough, they'll usually back off, break
out the check book, and let you do your job.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 5/10/2013 6:02 PM, Bob-O Schultze wrote:
Ron,
It certainly sounds like a failed diode (there are two) to me. Usually they
fail open, but it isn't unheard of that they might just avalanche when they see
the current of the other PVs. Solarworld would probably replace it under
warranty IF you return the dead module to them. How the hell do you do that?
I'd tell him to call them and see if they will let him record whatever test
procedures they want to see. This assumes, of course, that your DIY guy has a
decent DMM, etc. He might get lucky.
It's often a good faith gesture to help out a DIY in a situation like this, but
if I were you, I'd make it very clear that this is a one-time deal. Explain
that you are a pro who gets paid for your hard-won knowledge and expertise. If
he is like most DIY-ers, that will be the last you hear from him. A good deal
for you- you really don't want him as a BFF who feels like he can ring you up
every time he has a question, but continues to buy his stuff from
Cheaper-than-you-can-imagine.com Ya know?
Bob-O
On May 10, 2013, at 4:33 PM, Ron @ earthRight Solar wrote:
Hi Wrenches,
Wondering if anyone can shed some light on this. I have a customer who self
installed 4 x 165w Solarworld panels a few years ago (2008). It's a 12v nom.
battery and the panels are wired in parallel. They've been working fine for
five years on a full time household using a 3024i Blue Sky controller albeit
driving it well beyond it's max PV power recommendation as currently published
by Blue Sky.
However, now one of the panels has dropped from approx. 30-35v output to 13v.
When the failed panel is removed from the string the three remaining panels
come back to normal voltage and amp output but after about 15 minutes drop down
to around 13v on the Blue Sky display - even though the individual output from
each panel when unhooked and tested in full sun show about 35v. After turning
the system off and on again a few minutes later the normal voltages return but
drop again in about 15 min. The failed panel stays at 13v, does not recover.
I'm trying to do a little pro bono diagnostic for the guy who lives back in the
bush. I haven't been to the site but asked him to carefully check all the
wiring and he says it's fine. So two questions. First- is there a diode in the
failed Solarworld (sealed J box) that could have failed and if so is it
repairable? Second, any ideas what could explain the intermittent drop in
voltage output of the remaining three?
Ron Young
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