[RE-wrenches] Utility transformer limitations

[Christopher Warfel]

What happens if the study shows yes, that their no was wrong. Or does 
that never happen?😕

On 12/26/2022 12:48 PM, Jay via RE-wrenches wrote:
> If the utility is PG&E in my experience here is what happens
>
> They say yes or no to the interconnection.
> If no you have the option to request an engineering study to determine 
> how much solar. That study is at your expense, paid in advance and the 
> exact cost isn’t known until the study is done. Could be $500 to 
> $15,000 or more.
>
> I’ll be curious to know what happens
>
> Jay
>
>
>
>
>
>> On Dec 26, 2022, at 9:07 AM, Drake Chamberlin via RE-wrenches 
>> <re-wrenches at lists.re-wrenches.org> wrote:
>>
>> 
>>
>>
>> William,
>>
>> I ran into this once on an old transformer, which fortunately they 
>> changed at no cost. It was a 10 kW transformer on a 200 A (48 kW) 
>> service. They had some dimming of lights on heavy loads, and the 
>> transformer was changed out on that basis, at no charge.
>>
>> My questions for the utility would be?
>>
>>   * Are there any other PV systems feeding the transformer?
>>       o If so, what is their maximum production.
>>   * What size is the transformer?
>>   * What percentage of transformer capacity is allowed to be back-fed.
>>
>> If the math comes out in your favor, you will have a good case to 
>> escalate to the next level.
>>
>>
>> Good Luck,
>>
>> Drake
>>
>>
>> Drake Chamberlin
>>
>> Athens Electric LLC
>>
>> Ohio Electrical Contractor’s License 44810
>>
>> CO Master Electrician’s License 4526
>>
>> NABCEP Certified PV Installation Professional
>>
>> -------------------------------------------------------------------------------
>>
>> On 2022-12-25 13:58, William Miller via RE-wrenches wrote:
>>
>>> Wrenched:
>>>
>>> Merry Christmas to those of you that observe such traditions, or 
>>> substitute the winter festivity of your choice.
>>>
>>> I helped a previous employee install an Enphase IQ8 system on his 
>>> home.  He applied for the utility approval concurrently with his 
>>> building permit  The day he got his final inspection the utility 
>>> contacted him and claimed "The aggregate generation exceeds the 
>>> identified transformer rating" and refused him a Permission to 
>>> Operate letter.
>>>
>>> Adding up the service ratings of the homes on his secondary we get 
>>> about 336 kW of potential consumption. Adding the grid-tied systems 
>>> on his secondary we get about 16.5 kW.  How is it that the back-feed 
>>> exceeds the transformer rating?
>>>
>>> I would appreciate any insight on how to consider this situation and 
>>> how to fight it.
>>>
>>> Sincerely,
>>>
>>> William Miller
>>>
>>> Miller Solar
>>>
>>> 17395 Oak Road, Atascadero, CA 93422
>>>
>>> 805-438-5600
>>>
>>> www.millersolar.com <http://www.millersolar.com/>
>>>
>>> CA Lic. 773985
>>>
>>>
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>
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-- 
             Christopher Warfel
                      ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
                                 401-466-8978
<http://entech-engineering.com>

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