[RE-wrenches] Sanyo HIT module diode issues

[Brian Mehalic]

Did you test the voltage of the individual cell banks in the module with
the diodes out?


Brian Mehalic
NABCEP Certified Solar PV Installation Professional™ R031508-59
520.204.6639

Solar Energy International
http://www.solarenergy.org

SEI Professional Services
http://www.seisolarpros.com


On Thu, Jul 6, 2017 at 6:18 PM, Taiyoko Sadewic <
taiyoko at positiveenergysolar.com> wrote:

> Hi Brian,
> Thanks for the info. Yes I tested the diode properly.  I was concerned
> that I needed to test the diode under a load to get a valid test.
>
> Taiyoko
>
> On Thu, Jul 6, 2017 at 4:14 PM, Brian Mehalic <brian at solarenergy.org>
> wrote:
>
>> Did you use the Diode Test function on the meter?  If the diode is good
>> you should see around 0.4-0.8 V in the forward bias, and OL in reverse.  If
>> it is bad (open) you'll get OL in both directions, and if it is shorted
>> closed you'll get the 0.4-0.8 V reading in both directions.
>>
>> Shorted closed would be the failure mode that would indicate an
>> always-closed diode providing a permanent bypass path and thus a drop of
>> 25% of voltage per bad diode (or set of paralleled diodes).  (These have 4
>> diodes right?).
>>
>>
>>
>>
>> Brian Mehalic
>> NABCEP Certified Solar PV Installation Professional™ R031508-59
>> 520.204.6639 <(520)%20204-6639>
>>
>> Solar Energy International
>> http://www.solarenergy.org
>>
>> SEI Professional Services
>> http://www.seisolarpros.com
>>
>>
>> On Thu, Jul 6, 2017 at 4:31 PM, Taiyoko Sadewic <
>> taiyoko at positiveenergysolar.com> wrote:
>>
>>> Hi Wrenches,
>>> We were installing Sanyo HIT modules back in 2006-2007 and in 2014 we
>>> had a rash of bad Sanyo modules. The modules had distinct voltages below
>>> the good modules ie 50% or 75%.  Sanyo at the time (now Panasonic)
>>> indicated that it was a bad diodes from a lightning strike not covered by
>>> warranty.
>>>
>>> I finally got around to checking that out. I identified the purportedly
>>> bad diode in one module (four per module) that was performing at 75% and
>>> removed it. The diode appears to be fine using an ohm meter.  Is that a
>>> valid test?
>>>
>>> Anyone else have similar findings or experiences with this?  Could
>>> lightning blow apart the tab ribbons inside of the module?
>>>
>>> Thanks
>>>
>>> --
>>> <http://www.PositiveEnergySolar.com>
>>> Taiyoko Sadewic
>>> Employee-Owner
>>> NABCEP™PV Installation Professional
>>> NABCEP™Technical Sales
>>> 3209 Richards Lane  |  Santa Fe, NM 87507
>>> cell  505.570.0137 <505.699.9032>
>>> Taiyoko at PositiveEnergySolar.com  <Taiyoko at PositiveEnergySolar.com>
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>
>
> --
> <http://www.PositiveEnergySolar.com>
> Taiyoko Sadewic
> Chief Financial Officer | Employee-Owner
> NABCEP™PV Installation Professional
> NABCEP™Technical Sales
> 3209 Richards Lane  |  Santa Fe, NM 87507
> cell  505.570.0137 <505.699.9032>
> Taiyoko at PositiveEnergySolar.com  <Taiyoko at PositiveEnergySolar.com>
> www.PositiveEnergySolar.com
> <http://www.positiveenergysolar.com/>
>   <http://www.facebook.com/positiveenergysolar>
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