[RE-wrenches] [EXTERNAL] 208V residential service

[Dave Tedeyan]

Hi All,
I thought I'd report back on this one. First of all, ConEd gave a quote of
over $19,000 to drop in a 240V transformer. So much for that route.
The good news is that the IQ8A microinverters have been performing better
than expected. Even though the data sheet says it goes down to 211V, it has
connected and produced power every day so far without fail. Typically the
voltage in the morning is about 207V. Then I would have expected the
microinverters to produce much less power at the low voltage. I've seen the
AC voltage rise up to 216V, and if it was limited to the 1.45a as shown in
the datasheet, that would be 313w. It is rated for 349w continuous. I've
seen the microinverters put out 339w continuous on a good day. So the
current in the strings must be going higher than the rated value, and
fortunately that is okay here. So, the only real impact is that the
microinverters max out at about 10w less than rated power.

It is not often that products exceed expectations and do better than the
printed specs!
Cheers,
Dave

On Mon, Oct 21, 2024 at 1:03 PM White, Will <will.white at fluke.com> wrote:

> I've seen this issue with a condo building. A competitor had installed a
> set of Outback inverters that wouldn't work because of low AC voltage. They
> had to swap them out for an inverter that would work at 208.
> ------------------------------
> *From:* RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> on behalf
> of Dave Tedeyan via RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Sent:* Thursday, October 17, 2024 8:26 AM
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Cc:* Dave Tedeyan <dave at sungineersolar.com>
> *Subject:* [EXTERNAL] [RE-wrenches] 208V residential service
>
>
> *CAUTION:* This email originated from outside of the organization. Do not
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>
> Hi All,
>
> I was just out of town installing a system for a friend just North of NYC.
> I was confused when checking phase for consumption CT's when I found that
> there was 120V L-N, but 206V L-L. I went and found the transformer, and
> there was in fact one transformer for all the houses that I could see. It
> had 4 wires coming out of it, and each house was tapped onto 3 of them. So
> they actually are just using two legs of a 3 phase 208/120V distribution
> system.
>
> Has anyone seen this sort of thing before? I was amazed that a bunch of
> houses there all have 208V L-L, and it seems to not be causing problems.
> Granted my friend says his A/C is really weak and that they have had some
> funky problems with their electric oven. But they also just moved in last
> year, don't have many 240V (or 208V) appliances, and are not very
> electrical savvy, so they were clueless about this.
>
> Unfortunately this means that all the Enphase IQ8A's I just put on their
> roof are useless, unless I go back to put in a transformer or get the
> utility to do something about it. I am going to call the utility (Con Ed),
> but I was just curious if anyone has had a similar experience and whether
> their utility was open to changing it to 240V.
>
> Cheers,
> Dave
>
> --
>
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> Dave Tedeyan, P.E.
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