[RE-wrenches] Inverter output fluctuations

[Howie Michaelson]

Dave,
I'm pretty sure I have not done that test. I'm not currently in sure and
won't be for a couple of weeks, but maybe I can try it remotely. Went would
disabling the charger make a difference with an AC coupled backfeed issue?
Thanks,
Howie

On Mon, Jul 24, 2023, 10:45 AM Dave Angelini Offgrid Solar via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hey Howie, Can't remember but did you try disabling the charger in XW+ for a pulsation test ?
>
>
> *Dave Angelini Offgrid Solar
> "we go where powerlines don't"
> http://members.sti.net/offgridsolar/ <http://members.sti.net/offgridsolar/>
> e-mail  offgridsolar at sti.net <offgridsolar at sti.net>
> text 209 813 0060*
>
>
> On 2023-07-23 9:37 pm, Howie Michaelson via RE-wrenches wrote:
>
> Don,
> Thanks, but this is not the issue here.  The fluctuations happen anytime
> the AC coupled inverter connects to the XW+'s "grid", not just when the
> batteries are full.  The frequency only changes about 1/10 of a herz when
> it connects, but it doesn't matter what the voltage is of the batteries,
> the pulsation starts. Going over the settings with Eric Bentsen, we shut
> off the AC coupled option to prevent the frequency shifting - this made no
> difference.  We do have a contactor installed that disconnects the inverter
> from AC when the voltage starts elevating past the charge voltage and it
> has worked well for years. If I set up an AC coupled Off-Grid open loop
> system in the future, I'm thinking that I would look to disconnect the DC
> input as the batteries reach charged voltage - generally an easier cycling
> for the system to endure. There is also a smaller, legacy DC coupled array
> in this system which takes care of the finishing charge of the batteries
> through a charge controller. Again, it has all worked well in the past,
> only having any issues with AC fluctuations due to having the generator
> charging load set too high for the existing generator. This was solved by
> simply turning down the charge rate of the batteries and the visible light
> fluctuations stopped.
> Howie
>
> On Sun, Jul 23, 2023 at 11:42 PM don energysolarnow.com <
> don at energysolarnow.com> wrote:
>
> Howie-
>  it sounds like the XW+ is trying to curtail the Solar Edge by shifting
> frequency, and the loads don't like it.
> When off-grid and batteries are charged there is no place for all that AC
> coupled solar power to go.
> This is an issue windmill folks have too. The solution can be as simple as
> a dump load such as a water heater to absorb the excess energy.
> Tell the customer to turn the hot tub up high, or something like that.
> Heat up a bathtub in a greenhouse and plant bananas.
>
> DonBarch
> Energy Solar
>
> From: Howie Michaelson <Howie.Michaelson at gmail.com>
> To: Dave Angelini <offgridsolar at sti.net>, RE-wrenches
>         <re-wrenches at lists.re-wrenches.org>
> Subject: Re: [RE-wrenches] Inverter output fluctuations
> Message-ID:
>         <CAHMeMs=
> oOj_P0_a_sjyvw7_-+8kC9yVFSnm9PkWvgK-xnjx9MQ at mail.gmail.com>
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>
> Hi,
> I was finally able to get to the site with the light pulsating issue. It
> turns out it is that it directly corresponds to the AC coupled SolarEdge
> HDwave 6kW inverter.  Moreover, the pulsating gets stronger with higher
> output of the SolarEdge inverter (as more sun pouches more current through
> the inverter). And the hum of the XW+ very noticeably fluctuates in direct
> proportion to light fluxuations. It affects all the lights in the house,
> regardless of manufacturer, wattage or age. I did not have an oscilloscope,
> but looking at the Hz, it does sag very slightly to 59.9 when the SolarEdge
> is producing, down from a rock solid 60 Hz when the SE is not producing.
> The output voltage does not change at all.  The fluctuations in both the
> lights and the inverter hum immediately stops when the SolarEdge production
> is shut off. So it is clearly some interaction between the 2 inverters
> causing this issue.
>
> Has anyone dealt with this issue before? Does anyone have any suggestions
> for dealing with this, short of replacing the SolarEdge with a Schneider
> high voltage Charge Controller?
> Thanks,
> Howie
>
>
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