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Joined: Feb 2002
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I have seen where the PV installers would put them on the outside of the house. They called it "utility disconnect". Then that practice stopped.
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If you have the PV systems with the built in inverters on the panel, every night time (theoretically) the PV power would be disconnected from the Poco grid. That would be on the outside of the house. To me that is the safer install.
Last edited by harold endean; 05/16/11 09:32 AM.
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Gentlemen:
Back to my original quest please....
Our utility was requiring an AC disconnect (lockable) to isolate PV from the grid.
They (POCO) can no longer mandate it due to jurisdictional issues.
Can it be mandated via 705.21 without consideration of the inverter output being dependent on grid voltage???
John
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Can you explain the 'jurisdictional' issue that prevents the POCO from requiring the PV disconnect?
I would like to know how the POCO can be cutout of the decision to safely isolate the grid from the PV source. I have worked with all three major Calif utilities (SDG&E, SCE and PG&E) plus a couple of smaller ones (SMUD and SVP) and have yet to find one that would allow the interconnection without a visible blade, lockable PV disconnect.
While I agree it is not really necessary given the inverter's required anti-islanding features 'anything' can fail (including the anti-islanding features) and for their piece of mind they mandate the visible verification within their Rule 21 requirements.
I believe 705.21 could be referring to the AC switch required to meet 690.15 and 690.17, those switches are usually integral to the inverters and would not meet the Utilities 'visible' requirement nor would a circuit breaker in Calif since you can not 'visually' ensure the circuit is open.
I should note that I don't do RESI work, so what passes the AHJ's and Utility's inspections in that regard I can't comment on.
As far as being outside, I believe it's not required, but if it isn't and it's not adjacent to the Utility disconnect then a plaque would need to be provided at each disconnect (Utility and PV) showing the location of each per 230.2(E)
Last edited by Vindiceptor; 05/16/11 04:33 PM.
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Vin:
The only reason I was presented was 'not within the POCO tarrif'.
I have a email into the BPU to see if they have any reasons, but for now that's all I have.
John
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Means shall be provided to disconnect power production equipment, such as utility interactive inverters You need some kind of disconnect but I assume there is one in the inverter. When you say "lockable", that is the part that is not in 705.21.
Greg Fretwell
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You need some kind of disconnect but I assume there is one in the inverter. When you say "lockable", that is the part that is not in 705.21. The thing that negates most all inverter integral disconnects as being acceptable to the Utility is the "visible blades" part, very few of them have this feature and a circuit breaker is also unacceptable. Most inverter do have lockable disconnects of some sort, but lack the visual part so they can't tell if the device is actually opening the circuit. Anything out here over 30kW will be turned down immediately without this feature. The small Solectria inverters (10-95kW) are the only ones I know of that comply and that's only because they just tack off-the-shelf disconnects onto their inverters.
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Greg:
Removing the term 'lockable' from my question, would you then agree that 705.21 could be cited?
John
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That certainly means you need a disconnect. That gets further defined in 22 705.22 Disconnect Device.
The disconnecting means for ungrounded conductors shall consist of a manually or power operable switch(es) or circuit breaker(s) with the following features:
(1) Located where readily accessible
(2) Externally operable without exposing the operator to contact with live parts and, if power operable, of a type that could be opened by hand in the event of a power-supply failure
(3) Plainly indicating whether in the open (off) or closed (on) position
(4) Having ratings not less than the load to be carried and the fault current to be interrupted. For disconnect equipment energized from both sides, a marking shall be provided to indicate that all contacts of the disconnect equipment might be energized.
Last edited by gfretwell; 05/17/11 12:05 AM.
Greg Fretwell
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As always, I thank you!!!
John
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