[RE-wrenches] off-grid permitting problem

Kent Osterberg kent at coveoregon.com
Wed Dec 12 09:20:34 PST 2012


These code references should be all that is necessary to put the 
inspector on the right path. His requirement that the source be capable 
of 100 amps clearly conflicts with the intent of 690.10(A); it makes 
clear that the inverter system only needs to be large enough to operate 
the single largest load that it is intended to operate. Thus it is 
permissible for combinations of loads to overload the inverter and cause 
a nuisance shutdown.

You might also ask if he'd be happy with a utility service provided by a 
15-kVA transformer. While capable of substantial overloads, it is only 
rated to provide 63 amps continuously. Most 200-amp service panels don't 
really have 200 amps available except for short durations.

Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com
t: 541-568-4882

On 12/12/2012 4:43 AM, Jason Szumlanski wrote:
> See 690.10, 690.1, and 690.3.
>
>
> *Jason Szumlanski*//
>
> /Fafco Solar/
>
>
>
> On Wed, Dec 12, 2012 at 1:00 AM, William Miller 
> <william at millersolar.com <mailto:william at millersolar.com>> wrote:
>
>     Jeff:
>
>     There is a code passage that specifically states that one does not
>     need to provide full rated ampacity to a service.  I am sure you
>     can find it.
>
>     Find a way to prove, mathematically, that the system planned will
>     provide adequate power.  Create or find a spreadsheet listing all
>     appliances and wattages and system watt hours provided.  Dress it
>     up, put your logo on it and sell it to the building department.
>
>     William Miller
>
>
>
>
>     At 07:52 PM 12/11/2012, you wrote:
>
>         Content-Type: multipart/alternative;
>                 boundary="----=_NextPart_000_0006_01CDD7F2.373D3CB0"
>         Content-Language: en-us
>
>
>         We have a client that just had assembled on his rural property
>         a pre-fab modular home with  "normal" wiring and 200 amp main
>         panel and meter base.  However, landowners around his property
>         will not grant access for electric utility to cross and he
>         needs to move in ASAP.  He realizes that some day he should be
>         able to resolve this utility access but until then he wants us
>         to do an off-grid "basic" solar system with generator backup
>         so he can at least power lights, well pump, and basic
>         appliances.   His budget will not allow a fully off-grid solar
>         system so we wanted to do reduced solar and battery system
>         with larger generator to fill in on bad solar days.  He does
>         have good solar exposure and lots of cleared land, but figures
>         one day the solar and generator will become a backup system to
>         a future grid connection so does not want to spend any more
>         than absolutely necessary.
>
>         However ,this local inspector for this rural county has no
>         experience with solar and is expecting to see a 200 amp
>         service connection from the utility before allowing occupancy.
>          He did hint that a 100 amp service connection may be allowed
>         but nothing less.  I know NEC does mention that a panel does
>         not have to be supplied with the amount of service capacity it
>         is rated for, but what other code issues can I point out to
>         get this accepted without getting into a pis----- contest?
>
>         Thanks,
>
>         Jeff Yago
>
>
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