[RE-wrenches] Sanyo HIT module diode issues

[Taiyoko Sadewic]

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>
>> www.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/>
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