diy solar

diy solar

Sol-ark question re additional AC coupled array

Judoal said:
can’t use micro inverters. The combiner boxes have the negative side grounded and can’t deliver split-phase power for AC coupling. Only other solution is a small inverter to replace the CC. Space is limited.

i have an all electric house so additional power is necessary.
Click to expand...
Negative side ground is easy to deal with if the odd bonding is done in the combiner and not in the solar panels. Take out the combiner. However if you only have two conductors with no ground going to the array (which is NOT code compliant) then you will not be able to use microinverters, because they will most likely refuse to start up. While a MPPT can be readily fooled into running in this unsafe configuration.

Do you have photos of the wiring?

Judoal said:
Before I replaced my previous, all arrays were working fine, with all 4 arrays delivering expected power, before I replaced my old system, with some degradation due to age.
Click to expand...

Remind us what the old system is. It probably had SoC export settings to deal with non-communicating SCC, or had a communicating SCC.

The main advantage of a separate GTI is that it will always send the full power towards the grid. You can find outdoor rated GTI which might let you get around some of the limited space problems.

I think we're still sort of going in circles here on this thread, and it's not clear we can productively help. I think we've listed all the possible options. The most impactful contribution from you would be screenshots of settings and production graphs.

Another useful exercise is to do the cost-benefit analysis of different scenarios, however this is jumping the gun a bit.
 
n2aws said:
Cool.

While waiting for tech support, I'd strongly suggest you take a break from this for a bit, and clear your mind. Then, come back and re-read the last page or two, focusing specifically about that people are telling you about the behavior of your inverter and charge controller.

With a fresh pair of eyes, maybe it'll click.

Anyway, since I don't know sol-ark, I'll withdraw from the thread, and maybe someone with sol-ark experience can tell you specifically what config options to tweak.
Click to expand...
Double thumbs up for your participation, you've been very patient. (y) (y) ;)
 
tech support wasn't helpful. but I tried TOU. The draw from the battery side was about 2KW which was in excess of the load requirements and selling to both the load and the grid. But for some reason the CC stayed on float mode never going to MPPT and outputting just a few amps. All the draw was coming from the batteries which during the SOC decreased to 98% over the time period of this test.
 
Judoal said:
But for some reason the CC stayed on float mode never going to MPPT and outputting just a few amps.
Click to expand...
Staying on float mode is related to your settings. That could be normal. I do not understand what "going to MPPT" is or what you expect it to do? A few Amps is typical float current
 
Ampster said:
Staying on float mode is related to your settings. That could be normal. I do not understand what "going to MPPT" is or what you expect it to do? A few Amps is typical float current
Click to expand...
understood. what I was referring to is that the CC never came off float mode provide more power. I've gone through the CC settings but haven't figured it out yet. That's all I was indicating.
 
Judoal said:
tech support wasn't helpful. but I tried TOU. The draw from the battery side was about 2KW which was in excess of the load requirements and selling to both the load and the grid. But for some reason the CC stayed on float mode never going to MPPT and outputting just a few amps. All the draw was coming from the batteries which during the SOC decreased to 98% over the time period of this test.
Click to expand...

I found the manual to your CC here:

On page 53, Rebulk voltage is how you define when it should switch from float to bulk again.

Also, be aware that if this is a lithium battery, the charge curve is pretty flat.. you may need to get below 98% SOC for the battery voltage to dip low enough for the CC to "rebulk"

But check this setting, and see if your battery fell below that voltage for 90+ seconds. If not, drain the battery further or adjust rebulk accordingly.

A quick search of the internet also shows me that you may want to update the CC firmware. apparently they changed how rebulk works slightly in later firmware versions.
 
n2aws said:
I found the manual to your CC here:

On page 53, Rebulk voltage is how you define when it should switch from float to bulk again.

Also, be aware that if this is a lithium battery, the charge curve is pretty flat.. you may need to get below 98% SOC for the battery voltage to dip low enough for the CC to "rebulk"

But check this setting, and see if your battery fell below that voltage for 90+ seconds. If not, drain the battery further or adjust rebulk accordingly.

A quick search of the internet also shows me that you may want to update the CC firmware. apparently they changed how rebulk works slightly in later firmware versions.
Click to expand...
I have this manual and tried it and set the rebulk to the current float voltage. Then tried to reduce the float voltage but the CC wouldn't let me. Reset the bulk voltage back to default
 
Last edited:
Judoal said:
need GT inverter
Click to expand...
As much as I posted earlier in this thread about the value of AC coupling, I do not see a need for AC coupling in this situation. As I read more of this thread I think the lack of production on that one string may simply be incorrect Charge Controller settings or production being curtailed because the batteries may be full. I have asked for kWh data to support the need for more production and none has been forthcoming. I suggest you spend more time documenting the performance of your system and determine what your needs actually are in terms of kWh capacity before you decide whether AC coupling is what you actually need.

How many kWhs does your system produce in a year and what is your consumption on an annual basis?
 
Last edited:
Ampster said:
As much as I posted earlier in this thread about the value of AC coupling, I do not see a need for AC coupling in this situation. As I read more of this thread I think the lack of production on that one string may simply be incorrect Charge Controller settings or production being curtailed because the batteries may be full. I have asked for kWh data to support the need for more production and none has been forthcoming. I suggest you spend more time documenting the performance of your system and determine what your needs actually are in terms of kWh capacity before you decide whether AC coupling is what you actually need.

How many kWhs does your system produce in a year and what is your consumption on an annual basis?
Click to expand...



annual critical loads 16560kwh
Annual production. 11616kwh
 
Judoal said:
its an 0ff grid inverter, need GT inverter
Click to expand...
I'm not sure you'll find a GT inverter that will work with your ~ 100 VDC negative grounded array.
The 100 VDC could be rewired pretty easily in the combiner box to increase the voltage, however the PV negative to ground connection isn't helping. I'm pretty sure that every modern inverter I've seen is meant for floating (not grounded) PV array.
If you're willing pull new wire to the array, picking a GT inverter will be easy.
 
If not running a new ground through the conduit, maybe you can find a 10-20 year old grid tie inverter that will work with a grounded PV array.

Or maybe someone here knows of a grid tied inverter that will be happy with a grounded PV wiring.
 
That explains why your charge controller is always in float stage because the batteries are full. There is nothing wrong with your charge controller. If you want to get that array to put out more power you could always run your system on batteries overnight and charge them during the day from the charge controller. That is the least expensive way to get some of the 25% production you are trying to get.
 
I got the CC to sell 1500 watts. Set float voltage to the same as the inverter and put the inverter in time of use mode. When Vbatt < Vfloat, CC kicked in and a lot more power was sold than than from the arrays connected to the inverter. Still a few problems to solve yet.
 
Dunno. This was just a test today. There wasn’t much sun for one thing so 2500 watts output from the CC was pretty good for an aging array. When I stopped the test, the batts recharged from the grid rather than from than from the arrays. But making progress.

As for estimates,due to poor sun and shorter days, the 3 arrays were producing less than 20 kwh. I have to figure out how to get batteries recharged from the arrays rather than from the grid.
 
Last edited:
Judoal said:
I have to figure out how to get batteries recharged from the arrays rather than from the grid.
Click to expand...
As mentioned several times throughout this thread it is all about the settings and the SOC of the batteries when the sun comes out. You will want the batteries at a low SOC at daybreak so the charge controller will charge them. That means you want the SolArk to use the batteries overnight so the charge controller can charge them in the morning and you want to set the SolArk settings to charge as last resort. If that is too difficult you may need to spend some money to better utilize that one array. Because it has a different voltage from the other three, it would have to be on a separate MPPT controller and configured to put out enough voltage to meet the minimum to work with the SolArk. That means the existing three arrays would have to all go to one of the MPPT inputs. There is not enough information to know if that is possible or even an option. There is not much more I can offer beyond what has already been said.
 
Last edited:
You must log in or register to reply here.

Similar threads

C
AC coupled inverter
Replies
4
Views
300
millsan1
millsan1
G
Frequency shifting ports for EG4/Luxpower/Sol-Ark - not identical?
2
Replies
47
Views
1K
Cmiller
C
D
Sol-ark + Enphase musings
Replies
2
Views
574
cstar707
C
R
26KW Solar and Sol-Ark 15K Evaluation/Grid Sell Limit
Replies
9
Views
820
Dave911
D
J
Anyone ever combine PV Array and Wind Turbine with a Sol-Ark?
Replies
6
Views
1K
lekeeper
L

diy solar

diy solar
Back
Top