[RE-wrenches] Inverter output fluctuations

[Howie Michaelson]

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>
> Content-Type: text/plain; charset="utf-8"
>
> 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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