[RE-wrenches] Low OC Voltage

[Dave Tedeyan]

Drake,
If you want to find out for sure, often you should be able to open up the
jbox on the back and poke around. It certainly is somewhat destructive, but
you may find that either a diode is not the issue, or it is fixable.
Sometimes you do have to pull out potting though. I have restored modules
for second hand use that otherwise would have ended up in the dump this
way. Obviously though it wont be like new anymore.
Cheers,
Dave

*Dave Tedeyan, PE*
Senior Engineer | Taitem Engineering, PC

110 South Albany Street | Ithaca, NY 14850
o. *607.277.1118 x121*  f. 607.277.2119
www.taitem.com

Solar • Sustainability • Energy • Design
B-Corporation Best for the World 2018 Honoree


On Thu, Jun 13, 2019 at 10:26 PM <drake.chamberlin at redwoodalliance.org>
wrote:

> The outside temperature was unseasonably cool, maybe 55 degrees.
>
>
>
> ----- Original Message -----
> From:
> "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
>
> To:
> "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Cc:
>
> Sent:
> Thu, 13 Jun 2019 09:25:39 -0400
> Subject:
> Re: [RE-wrenches] Low OC Voltage
>
>
> Drake,
> At what temperature did you get that reading? If it was very hot, then
> that could just be poor temperature characteristics of the module. I have
> run into some modules, specifically Suniva's, that just do very poorly in
> warm temperatures. Otherwise, if the voltage is approximately 2/3 of what
> you would expect, then it is usually an issue in the module jbox. Either a
> bad diode or failed solder connection. This case is odd, because it is a
> little bit more than 2/3 the voltage. So maybe it was very cold with 1/3
> the module not working, or very hot. Also, taking a look with an IR camera
> when the system is functioning can often show if 1/3 the module is not
> working or if there are some bad cells in the module.
>
> Cheers,
> Dave
>
> *Dave Tedeyan, PE*
> Senior Engineer | Taitem Engineering, PC
>
> 110 South Albany Street | Ithaca, NY 14850
> o. 607.277.1118 x121  f. 607.277.2119
> www.taitem.com
>
> Solar • Sustainability • Energy • Design
> B-Corporation Best for the World 2018 Honoree
>
>
> On Tue, Jun 11, 2019 at 7:05 PM Drake <
> drake.chamberlin at redwoodalliance.org> wrote:
>
>> Hello Wrenches,
>>
>> Would you expect a low open circuit voltage in a module to be due to a
>> problem in the J-box / diodes or the module itself? The OC voltage read
>> about 28.3 V, where as the STC OC voltage of the module is 37.3.
>>
>> The module is an LDK 240, which means no warranty.
>>
>> Thanks,
>>
>> Drake
>>
>> Drake Chamberlin
>>
>>
>>
>>
>>
>> *Athens Electric LLC OH License 44810 CO License 3773 NABCEP Certified
>> Solar PV 740-448-7328*http://athens-electric.com/
>>
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