[RE-wrenches] not sure what's going on here

[Ray Walters]

Take a charge controller with you that is sized for that array.

R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 5/12/2013 11:57 PM, Ron Young wrote:
> Hello all and thank you for the illuminating replies. One thing that immediately comes to mind is that I (we) are relying on the clients description of what is going on. I have not visited the site but it looks like it's in the cards as this seems like it could be a problem with several moving parts. The description I received from the owner is as follows:
>
> 1/ one of the 4 modules is only putting out about 13 volts. This is a persistent condition and does not go away. So from this I conclude that diodes have failed.
> 2/ the remaining 3 modules connected to the 3024i operate in a normal voltage range but after about 15 minutes drop to around 13 volts. Once disconnected from the controller then reconnected this condition repeats: normal then dropout after about 15 min. So from this I conclude that either the firmware is at fault or there is another cause as suggested by Dan "heating of the PV is causing one or more bypass diodes in one or more of the remaining
> modules to fail short intermittently".
>
> I'll try and work out a site visit to chase this one down and report back. I've also emailed Rick at Blue Sky. Once again thanks for the considered responses.
>
> Ron Young
>
> On 2013-05-12, at 10:22 AM, "Larry Crutcher, Starlight Solar Power Systems" <larry at starlightsolar.com> wrote:
>
>> I have a tendency to read between the lines and try and perceive things unstated. Just my nature. I doubt that the module removed from the circuit stays at 13Vdc. Ron said "...the normal voltages return but drop again in about 15 min". Because of the 3024 software issue I think this is affecting all modules. Also, " the individual output from each panel when unhooked and tested in full sun show about 35v". Each meaning the 3 or all 4? Ron, please clarify this. Have you been to the site or was this the report from the owner?
>>
>> Anyone that says, "41 years in solar energy …" is bound to be an enlightened, albeit aged fellow. Wear it as a badge. Actually the reference was in general as I view most of us battery wrenches as graybeards.
>>
>> Larry
>>
>>
>>
>>
>>
>> On May 12, 2013, at 7:45 AM, Exeltech <exeltech at yahoo.com> wrote:
>>
>> Hello Larry,
>>
>> A firmware upgrade may address some aspects of the issue, and
>> is certainly a recommendation, but it doesn't account for the
>> one PV that exhibits 13Vdc output when it's completely out of
>> the circuit.
>>
>> That characteristic clearly exemplifies a failure within the PV
>> module itself.
>>
>> It's entirely possible more than one failure mechanism is involved
>> here, such as something within the PV, and other that's related
>> to the firmware.  Multiple-issue failures are some of the most
>> frustrating and challenging of all fault analyses.  Then add
>> distance to the equation ....
>>
>>
>> Thanks too for the reference to "aged".
>>
>>
>> Dan
>>
>>
>> --- On Sun, 5/12/13, Larry Crutcher, Starlight Solar Power Systems <larry at starlightsolar.com> wrote:
>>
>>> From: Larry Crutcher, Starlight Solar Power Systems <larry at starlightsolar.com>
>>> Subject: Re: [RE-wrenches] not sure what's going on here
>>> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
>>> Date: Sunday, May 12, 2013, 9:30 AM
>>> Fellow Wrenches,
>>>
>>> I realize that many of you are offering your time and
>>> comments in a genuine effort to help Ron, however, the
>>> problem he described is the EXACT behavior of all early
>>> 3024i controllers. This happened with overloaded controllers
>>> operating in 24 to 12 downconversion, just like in this
>>> case. When the 3024 would reach current limiting, the
>>> controller will lock itself to half the input voltage.
>>> Because high power is still available, the controller would
>>> still function and many did not even know they had a
>>> problem. By disconnecting PV and battery and reconnecting,
>>> the 3024 will reboot and the problem will not occur again
>>> until current limit is reached. Note that this only happens
>>> when using high voltage PV and down converting to 12Vdc.
>>>
>>> Blue Sky Energy is our #1 selling controller and we have
>>> installed over 500 3024i's and 3024iL's. When I first
>>> discovered this issue and reported it, Rick at Blue Sky was
>>> able to duplicate it and made appropriate changes. Upgrading
>>> firmware always corrected the issue.  So, with respect
>>> to the many aged but wonderful minds on this list, I highly
>>> suggest the controller upgrade first. At the very least,
>>> reboot the controller in the morning and observe as it
>>> reaches the limit.
>>>
>>> Larry Crutcher
>>>
>>>
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