[RE-wrenches] Sol-Ark AC Coupling Issues

Thu Jan 20 08:08:31 EST 2022

Hi Vince,
That is a very complex design, so many breaker interlocks but I think I
understand the intent!

When you say that you have programmed the Radian for AC coupling, that
really isn't programming it to be AC coupled on its AC input side, its
saying that it can AC couple inverters on its AC load side.  Remember the
Radian is a grid forming inverter on the load side (controls voltage and
freq) and a current source on the grid input (does not control voltage and
freq).  How you are connecting solar modules to the Radian will tell you
how to set this setting.  If you are using charge controllers, you don't
want AC coupling here.

Look closely at the grid settings in the Radian, this will control how it
will interact with the Sol-Arks at its input.  Its looking at the voltage,
frequency, impedance etc. on the input and deciding if it should push
current.  Maybe there is a setting that needs opened up a bit?  Be cautious
here.

Anyway, here is what I would try after looking closely at the grid settings
in the Radian:

Measure DC buss voltage (Blue Ion voltage) throughout this process.  Do you
see any abrupt changes in the DC buss voltage?  At what SOC?   Do you have
solid communication between Sol-Ark and Blue Ion (Namaka box)?  Do you ever
see it drop and go to voltage mode instead of SOC communication mode?  Does
the same issue occur if you use voltage control on the Sol-Ark?

Turn on your DC coupling, and slowly ramp up the AC coupled current (sell
current setting on the Radian).  Does any AC coupled current trip it off?
I suspect if the sell current is lower than the load current, there should
be no freq/watt shift.
If you discharge the batteries deeply, does this make a difference?
Since you have an open Gen Input Breaker, why not put the Radian GT
connection on it?
Do you really want the Radian to be able to discharge the Blue Ion battery
bank at night?

Customer designs are tough, Good Luck!

On Wed, Jan 19, 2022 at 10:16 PM Vince McClellan <
vince at solarenergydesign.com> wrote:

> Thanks Pieter
> We seem to have the opposite problem from what you are experiencing. Our
> freq-watt regulation of the Radian inverter by the Sol-Ark inverters seems
> to be actuated by the DC power from the solar array that is DC connected to
> the Sol-Ark inverters. It is supposed to be actuated by the SOC of the Blue
> Ion batteries, but that is inconsistent at best. We can turn the DC power
> from the solar array on on the master inverter, but when we try using the
> MPPT channels on the two other inverters it briefly actuates the freq-watt
> function of the Sol-Ark disconnecting the Radian inverter.
>
> Vince McClellan
> Energy Design
> NABCEP PV Installation Professional
> p. (541) 485-8122  f. (541) 338-8202
>
> If you have received this email and are not the intended recipient please
> delete this email. Copying, or using any part, content, or attachment of
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>
> On Wed, Jan 19, 2022 at 8:20 PM Pieter Huebner <
> pieter at offgridenterprises.org> wrote:
>
>> Vince, For what it is worth:
>>
>> We have also been working on similar issues when using multiple Solark
>> inverters connected in parallel. The issue has been that parallel Solark
>> inverters don't seem to be able to properly regulate the battery charge
>> voltage. Although Solark technical support has been outstanding, and with
>> their help we have diminished the severity but not solved the issue.  For
>> the sites that we currently have deployed for the interim we had to resort
>> to turning down the charge voltage set points in order to protect the
>> Lithium batteries. and avoid BMS shutdowns. We have a client with an
>> existing outback system and were planning to expand the existing system
>> using AC bussed Solark 12K inverters with additional battery and solar
>> capacity (the site is 100% off grid, and has evolved into a micro grid),
>> but are now going a different direction. Although we have not yet attempted
>> an AC bussed Solark system, I suspect that the issues you are having are
>> related to the battery voltage regulation problem we have experienced.
>>
>> Pieter
>>
>>
>>
>>
>>
>> *From:* RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> *On
>> Behalf Of *Vince McClellan
>> *Sent:* Wednesday, January 19, 2022 5:16 PM
>> *To:* RE-wrenches <RE-wrenches at lists.re-wrenches.org>
>> *Subject:* [RE-wrenches] Sol-Ark AC Coupling Issues
>>
>>
>>
>> Is anyone on the list familiar with AC coupling Sol-Ark inverters?
>>
>>
>>
>> We haven't been able to AC couple an existing Outback Radian system to a
>> new system that we built with 3, Sol-Ark 12K inverters and 3, Blue Ion
>> batteries. Each time we have tested the system the Sol-Ark inverters accept
>> the power from the Radian inverter until we turn on the DC power from the
>> new solar array to the Sol-Ark inverters. As soon as there is
>> significant DC power coming from the solar array the Sol-Ark inverters
>> freq-watt turns on for a brief second and disconnects the Radian inverter
>> even when the Blue Ion batteries are below the programmed state of charge
>> threshold. If we don't turn on the DC power from the new solar array the
>> Radian will connect and stay connected.
>>
>>
>>
>> We have been working with Sol-Ark for several months now to get this
>> system to accept the incoming power from the Radian without freq-watt
>> kicking in on the Sol-Ark inverters and disconnecting the Radian inverter.
>> Sol-Ark has sent two software revisions to the Sol-Ark inverters and we are
>> still experiencing the same problem.
>>
>>
>>
>> Can anyone think of what we might be missing and where to direct our
>> troubleshooting efforts next?
>>
>>
>>
>> Thanks,
>>
>>
>> Vince McClellan
>>
>> Energy Design
>>
>> NABCEP PV Installation Professional
>>
>> p. (541) 485-8122  f. (541) 338-8202
>>
>> If you have received this email and are not the intended recipient please
>> delete this email. Copying, or using any part, content, or attachment of
>> this email is strictly prohibited.
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-- 

Mac Lewis

*"Yo solo sé que no sé nada." -Sócrates*
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