Sol-ark question re additional AC coupled array

[400bird]

I have an all electric house so additional power is necessary.

Then program the inverter to use more energy from the battery? If the battery is full, the charge controller doesn't have anywhere to put the juice.

You keep saying you can't change the array because the negative side is grounded. Why can you change that? That's a pretty old standard and not in practice currently. Seems like you could remove the bond between ground and PV negative. Or if you need to keep the negative ground, you could do so, but in rewiring remove multiple panels from that ground connection.
Post pics of the junction box if you want to investigate that further, I'm sure someone can draw on a potential solution.

 

[Judoal]

These were wired over 10 years ago and are 150’ sway. Rewiring is not practical. The power is not being drawn from the batteries.

 

[n2aws]

The power is not being drawn from the batteries.

Right.

We're saying, change the settings on the inverter so that power *is* being drawn from the batteries. Then, the CC will output current.


Right now, there is nowhere for that energy to go, so the CC isn't taking the PV power, and using it for the batteries.

You have to understand that for all intents and purposes, the CC is a dumb device. if the batteries are sitting at the voltage you told the CC to charge the batteries to, the CC thinks it's job is done, and will act accordingly. "no more power is needed for the batteries, so I won't make any more power".

Give the power somewhere to go. Set the solark to pull from the batteries. As the batteries discharge, your CC will see a difference and "well, now power is needed, all systems are go!"

 

[400bird]

So, you aren't willing to change the SolArk programming. You just want to throw money at it and buy a grid tied inverter to get AC from that array?

 

[Judoal]

Don’t reinterpret what I wrote. Another inverter is but one option. I asked SA tech support about configs . I have not determined the configs on my own other than TOU which is fixed times and not dependent on power on solar gain.

 

[Judoal]

Right.

We're saying, change the settings on the inverter so that power *is* being drawn from the batteries. Then, the CC will output current.


Right now, there is nowhere for that energy to go, so the CC isn't taking the PV power, and using it for the batteries.

You have to understand that for all intents and purposes, the CC is a dumb device. if the batteries are sitting at the voltage you told the CC to charge the batteries to, the CC thinks it's job is done, and will act accordingly. "no more power is needed for the batteries, so I won't make any more power".

Give the power somewhere to go. Set the solark to pull from the batteries. As the batteries discharge, your CC will see a difference and "well, now power is needed, all systems are go!"

The float voltage of the CC is a bit greater than that for the array. The power does have some place to go, the grid. Looking
at the graphical displays of power flow. The power from the DC coupled array goes to both the load and the grid. I waiting to hear back from tech support.

The CC float voltage is slighty higher than the inverter’s. If set lower the CC registers that the batteries are full, other than TOU haven’t found a setting to draw from the batteries. 1st inverter priority is fixed at array first .

 

[n2aws]

The float voltage of the CC is a bit greater than that for the array. The power does have some place to go, the grid. Looking
at the graphical displays of power flow. The power from the DC coupled array goes to both the load and the grid. I waiting to hear back from tech support

I think you're just not understanding what we're telling you man.


your solark has *no idea* something on the DC bus is providing additional power than what it knows about. As such, it's NOT going to put additional power onto the grid, unless you specifically tell it to do so.

Since the sol-ark isn't going to put additional power to the grid, the CC isn't going to *produce* the power to charge the battereis.

You'll specifically need to tell the solark that it's allowed to pull from batteries to push to grid. That isn't the standard behavior (most people use batteries for backup, they don't want to sell *battery* power to the grid and discharge the batteries, but *you* do, because of the extra CC.

I don't know the sol-ark config options to tell you what settings to change. But using my inverter as an example, I can tell it that "between 9am and 4pm, allow the batteries to drain to XYZ state of charge. which would allow it to sell from the battery to the grid. In the case of my adding anohter CC that doesn't communicate with the inverter, it'd just sit there until the battery was low enough to accept some current, then the CC will start producing power from the PV array.

 

[Judoal]

I think you're just not understanding what we're telling you man.


your solark has *no idea* something on the DC bus is providing additional power than what it knows about. As such, it's NOT going to put additional power onto the grid, unless you specifically tell it to do so.

Since the sol-ark isn't going to put additional power to the grid, the CC isn't going to *produce* the power to charge the battereis.

You'll specifically need to tell the solark that it's allowed to pull from batteries to push to grid. That isn't the standard behavior (most people use batteries for backup, they don't want to sell *battery* power to the grid and discharge the batteries, but *you* do, because of the extra CC.

I don't know the sol-ark config options to tell you what settings to change. But using my inverter as an example, I can tell it that "between 9am and 4pm, allow the batteries to drain to XYZ state of charge. which would allow it to sell from the battery to the grid. In the case of my adding anohter CC that doesn't communicate with the inverter, it'd just sit there until the battery was low enough to accept some current, then the CC will start producing power from the PV array.

Please. I understand TOU settings. That’s not what I’m looking for since its fixed and will draw down the batteries when. There is is no sun. The grid will then recharge the batteries. Not ideal. I’ll post when
I hear back from tech support.

 

[n2aws]

Please. I understand TOU settings. That’s not what I’m looking for since its fixed and will draw down the batteries when. There is is no sun. The grid will then recharge the batteries. Not ideal. I’ll post when
I hear back from tech support.

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.

 

[n2aws]

The power does have some place to go, the grid. Looking
at the graphical displays of power flow. The power from the DC coupled array goes to both the load and the grid

the huge key difference that you are missing here:

The integrated MPPT's are able to communicate with the rest of the sol-ark, and it can make intelligent decisions about how to handle the power the PV is generating. INCLUDING selling that excess to the grid.

This communication simply doesn't exist with the additional MPPT. It's quite literally a dumb device, as has been explained multiple times. It's *only* job in life, is to charge the batteries up to the settings you specify in it's config. Once the battery is at that level, the CC has done it's job and will back off until it decides it has more work to do. Based on your comments, I'm 99.999% sure this is whats going on.

The *reason* we've mentioned setting the sol-ark to sell battery power to the grid, is so that the battery voltage drops a little bit, so the dumb CC can see a need for power, and "wake up".

If you are concerned about it charging the batteries from utility.. disable that setting. Let the extra PV and CC charge it, as it's intended.

I specifically mentioned TOU, to allow the inverter to sell from battery to the grid during sunshine hours only, so it can't deplete your batteries overnight. This allows your batteries to drain a little bit while the sun is shining, and allows your additional CC to do it's thing. but when the sun goes down, stop selling from battery to grid.

But yeah man, step away from this for a bit and clear your mind. then, re-read and see if it makes sense.

 

[zanydroid]

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.

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?

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.

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.

 

[zanydroid]

(I'm on the same page with n2aws on all the suggestions.

I'm also inclined to dip out of the thread for a while)

 

[MaikaiLifeDIY]

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.

Double thumbs up for your participation, you've been very patient.

 

[Judoal]

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.

 

[Ampster]

But for some reason the CC stayed on float mode never going to MPPT and outputting just a few amps.

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

 

[Judoal]

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

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.

 

[n2aws]

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.

I found the manual to your CC here:

https://www.outbackpower.com/downloads/documents/charge_controllers/flexmax_6080/owner_manual.pdf

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.

 

[Judoal]

its an off-grid inverter. need GT inverter. I've looked all the inverters on Signaturesolar. Haven't found any suitable including size limitations. Thanks

 

[Judoal]

I found the manual to your CC here:

https://www.outbackpower.com/downloads/documents/charge_controllers/flexmax_6080/owner_manual.pdf

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.

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

 

[Ampster]

I've gone through the CC settings but haven't figured it out yet.

The post just before this one should give you the details on how to change the rebulk voltage.