[RE-wrenches] Two systems on one building with separate services

Fri Mar 14 14:56:44 PDT 2014

Ah...OK

Looks like you have two options:

Locate the shop's inverter on the house, and run 240 VAC the 100 feet to the shop, where it will connect at the shop's service entrance.

Or, locate the inverter at the shop, and run the PV array DC the extra 100 foot distance.

Which is better? Electrically, I don't think that it really matters much.

With the inverter on the house, you are adding a 100' of AC wiring, so you need to make sure that any voltage drop does not cause the inverter to operate at too high an output voltage. If the utility service has already higher than normal AC voltage, that could cause the inverter to shut off due to high AC voltage. Running that distance as DC would not give you that potential issue. You still lose some power due to voltage drop of course (either AC or DC), but as long as that doesn't cause the inverter to operate below its MPPT DC voltage window, it won't effect it.

In either case, you will need an approved disconnect at each location, in other words, on each end of that 100' line. And good signage.

And I would recommend surge/lightning protection on both ends.

However, if you have the shop's inverter on the house, that also means that you have an AC connection from the shop's Service present at the house. This is where 230.2 may apply. You have two separate buildings with two separate Services. 230.2 applies to single, or physically connected, buildings with multiple Service entrances. It's about safety, so that fire fighters or other emergency personnel can be sure that if they pull a service meter, that they are cutting all the power to that structure. If you have an AC connection to that other Service, the AHJ may take issue with it under 230.2, even if you have a lockable disco,  good signage, and the house meter and shop disco are close together. You should consult with your AHJ.

Brian Teitelbaum
AEE Solar

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Nathan Charles
Sent: Friday, March 14, 2014 2:23 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Two systems on one building with separate services

No, the shop service is located on the shop building.

-N

On Fri, Mar 14, 2014 at 4:52 PM, Brian Teitelbaum <bteitelbaum at aeesolar.com<mailto:bteitelbaum at aeesolar.com>> wrote:
Are both services (and meters) on the house? Or is the shop service located on the shop building?

Brian

From: re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at lists.re-wrenches.org> [mailto:re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at lists.re-wrenches.org>] On Behalf Of Nathan Charles
Sent: Friday, March 14, 2014 1:43 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Two systems on one building with separate services

The distance between the building is about 100'.

The residential service is a 200A service but the workshop is 400A because of large of equipment and can't be combined at this point.

On Fri, Mar 14, 2014 at 4:03 PM, Brian Teitelbaum <bteitelbaum at aeesolar.com<mailto:bteitelbaum at aeesolar.com>> wrote:
Nathan,

What is the distance between the buildings, and where are the utility meters located?

What are the sizes of the Services? 200A?

Can both buildings be powered from a single Service? Why is the workshop metered separately?

Brian Teitelbaum
AEE Solar

From: re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at lists.re-wrenches.org> [mailto:re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at lists.re-wrenches.org>] On Behalf Of Nathan Charles
Sent: Friday, March 14, 2014 12:05 PM
To: RE-wrenches
Subject: [RE-wrenches] Two systems on one building with separate services

Hi Wrenches,

I've got an issue that's got me stumped and I was hoping somebody could give me some suggestions.

We have a customer who has two meters, one on the house and one on a workshop.  The workshop is heavily shaded and it's zoned residential so meter aggregation isn't a possibility.   The customer is hoping to put two separate PV systems on the house one for each meter with the inverters mounted in the garage.  It seems like that sets me afoul of the intentions of 230.2 Number of services, but if I remote one set of inverters and run DC I'm not quite sure how to think through the disconnecting requirements.

Any advice or suggestions on if or how this might be possible?

--
Nathan Charles
Engineer
NABCEP Certified PV Installation Professional #042013-20
Paradise Energy Solutions

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Nathan Charles
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NABCEP Certified PV Installation Professional #042013-20
Paradise Energy Solutions
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Nathan Charles
Engineer
NABCEP Certified PV Installation Professional #042013-20
Paradise Energy Solutions
(717) 283-2021 direct
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