[RE-wrenches] Low OC Voltage

Thu Sep 26 14:27:55 EDT 2019

This is a follow up on an old post about a failed 
LKD module. I wrote that I'd give follow up 
information when it became available.

It turned out that some of the fine circuitry on 
the face of the module was fried: according to my friend, it looked welded.

Drake

At 09:59 AM 6/19/2019, drake.chamberlin at redwoodalliance.org wrote:
>Dave,
>
>I gave the module to a friend who is going to go 
>into the J-Box. If there are any conclusions I 
>can post them on the list, but don't know when she plans to attempt the repair.
>
>Thanks,
>
>Drake
>
>
>
>----- Original Message -----
>From:
>"RE-wrenches" <re-wrenches at lists.re-wrenches.org>
>
>To:
>"RE-wrenches" <re-wrenches at lists.re-wrenches.org>
>Cc:
>
>Sent:
>Tue, 18 Jun 2019 14:57:47 -0400
>Subject:
>Re: [RE-wrenches] Low OC Voltage
>
>
>Drake,Â
>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,Â
>Dave
>
>Dave Tedeyan, PE
>Senior Engineer | Taitem Engineering, PC
>
>110 South Albany StreetÂ | Ithaca, NY 14850
>o. 607.277.1118 x121Â  f. 607.277.2119
><http://www.taitem.com>www.taitem.com
>
>SolarÂ Â SustainabilityÂ Â EnergyÂ Â Design
>B-Corporation Best for the World 2018 Honoree
>
>
>On Thu, Jun 13, 2019 at 10:26 PM 
><<mailto:drake.chamberlin at redwoodalliance.org>drake.chamberlin at redwoodalliance.org> 
>wrote:
>The outside temperature was unseasonably cool, maybe 55 degrees.
>
>
>
>----- Original Message -----
>From:
>"RE-wrenches" 
><<mailto:re-wrenches at lists.re-wrenches.org>re-wrenches at lists.re-wrenches.org>
>
>To:
>"RE-wrenches" 
><<mailto:re-wrenches at lists.re-wrenches.org>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,Â
>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,Â
>Dave
>
>Dave Tedeyan, PE
>Senior Engineer | Taitem Engineering, PC
>
>110 South Albany StreetÂ | Ithaca, NY 14850
>o. 607.277.1118 x121Â  f. 607.277.2119
><http://www.taitem.com>www.taitem.com
>
>SolarÂ Â SustainabilityÂ Â EnergyÂ Â Design
>B-Corporation Best for the World 2018 Honoree
>
>
>On Tue, Jun 11, 2019 at 7:05 PM Drake 
><<mailto:drake.chamberlin at redwoodalliance.org>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/>http://athens-electric.com/
>
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