[RE-wrenches] Combining Multiple Inverters

[Jason Szumlanski]

705.12(D) reads, "... the interconnection provisions for the
utility-interactive inverter(s) shall comply with (D)(1) through (D)(7)."
That's inverters - plural. The interconnection must be protected by
dedicated OCPD, not each inverter individually. Microinverters comply
because of this interpretation.

That said, I've never done it. An accumulator panel is pretty cost
effective when you consider the alternative cost of an enclosure and the
Polaris connectors. I guess if you are making the Polaris connections
inside the main load center or inside an inverter you can eliminate the
cost of a dedicated enclosure. There would be some material and labor
savings.

​If the inverter has a maximum OCPD rating, you will be limited by that.
​Microinverters "get around" that by the wire and inverter being
sized/rated for the entire maximum string.

Jason Szumlanski

​Fafco Solar​



On Wed, Jun 25, 2014 at 10:40 PM, Isaac Opalinsky <
David.Opalinsky at sunpower.com> wrote:

>  Then how do we install microinverters?  705.12(D)(1) says OCPD for each
> inverter is required at the point of interconnection with distribution
> equipment.  But as long as the conductors are sized to the OCPD, we follow
> the branch-circuit/feeder tap rules, and the inverter’s maximum OCPD limit
> is not exceeded, what is the issue?  I’m assuming the inverter’s maximum
> OCPD is usually the limiting factor, but I’ve been intrigued by the fact
> that the ABB TRIO has an option for AC OCPD in the inverter – it seems like
> there must be a cost-effective solution for tapping a trunk cable with a
> string inverter just as we do with microinverters.  Has anyone tried this?
>
>
>
> *Isaac Opalinsky *| Technical Trainer | *SunPower Corporation*
>
> Desk 443-569-3476 | Cell 443-277-6286
>
>
>
> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
> Behalf Of *Glenn Burt
> *Sent:* Wednesday, June 25, 2014 10:19 PM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] Combining Multiple Inverters
>
>
>
> Code requires OCPD on the output of each inverter, so not sure where the
> savings would be..
>   ------------------------------
>
> *From: *Corey Shalanski <cshalanski at joule-energy.com>
> *Sent: *‎6/‎25/‎2014 21:19
> *To: *RE-wrenches at lists.re-wrenches.org
> *Subject: *[RE-wrenches] Combining Multiple Inverters
>
> I am curious about best practices for combining the output of multiple
> inverters:
>
>    - We are considering using an insulated tap "Polaris/Burndy" connector
>    in lieu of a solar accumulation panel. We would then run the output of this
>    tap connector through a fused disconnect and on to the interconnection.
>    Does anyone else do this?
>    - In the above scenario, how should we size the wire between each
>    inverter's output and the tap connector? Since there is no OCPD on this
>    wire, would we have to use the same wire gauge as the combined output? or
>    can we get away with sizing each wire according to its associated inverter
>    output rating?
>
>  --
>
> Corey Shalanski
>
> Joule Energy
>
> New Orleans, LA
>
> ᐧ
>
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