[RE-wrenches] Inverter output fluctuations

[Dave Angelini Offgrid Solar]

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/
e-mail  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 [1] 
> <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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Links:
------
[1] http://energysolarnow.com
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