Off Set Enable Question.

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pss
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Off Set Enable Question.

Post by pss »

At 4 PM I have my system switch to Minigrid until 9 PM when it then switches back to Grid tied. My batteries drop from 100% SOC at 4 PM to 80% at 9 PM. In the next morning, my batteries are charged by the charge controllers only as the inverter's charger is OFF. However, I have noticed that even though I am in grid tie sell mode, the inverter's OFF SET mode is disabled and no selling takes place. My chargers go from BULK to ABSORB to FLOAT and PV harvest very low since OFF SET is disabled. If I manually enable the OFF SET tab, the inverter provides power and also SELLS. So what am I missing that is turning off the OFF SET mode when I go to Minigrid and not turning it back ON when I go back to Grid Tied?
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Re: Off Set Enable Question.

Post by fcwlp »

I have a system that I switched between grid-tied and mini-grid without selling being an issue but that system was charging from the grid at night.

In OpticsRE for the inverter's AC input tab when "Grid Input Mode" is set to "grid tied," is the "offset enable" also set to "yes."
pss
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Re: Off Set Enable Question.

Post by pss »

So during the day OFFSET ENABLE is yes for the inverter. Minigrid and then grid tie cycle from 4 PM until 9 PM. After 9PM when the system is back in grid tied, the inverter still says OFFSET ENABLED. However, in the morning the inverter OFFSET is NOT ENABLED. So it is probably one of the MIDNIGHT settings that take place effecting it. If I leave offset enable in the disabled position, the chargers will go through bulk/absorb and then float and then about an hour after that the PV harvest is very low (< 2kW) and and one of the chargers will even be in the silent mode. As soon as I enable the inverter offset, the chargers switch in bulk and the PV harvest jumps to >6 kW and selling begins.

So it appears there is a bug in Optics RE that is switching settings if the system was in Minigrid at a point in the day and then even if no longer in Minigrid, there is "leftover" action taking place.
fcwlp
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I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
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Re: Off Set Enable Question.

Post by fcwlp »

I put a system that matches your 8048A and Mate3s into Minigrid from 4pm to 8pm and Grid-Tied with offset the remainder of time. It is also on OpticsRE. If I forget to update you in a couple of days, send me a PM.
fcwlp
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I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
Location: 80 miles NE of Phoenix at 5500'

Re: Off Set Enable Question.

Post by fcwlp »

Short update, with "Charger Operating Mode" set to on, the system started selling first thing in the morning. I have now switched to off to more close match @pss's setup.
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Re: Off Set Enable Question.

Post by raysun »

That grid interactive stuff confuses the h-e-double-hockey-sticks out of me.

Glad I'm nowhere near a power line (figuratively speaking.)
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Re: Off Set Enable Question.

Post by provo »

raysun wrote: Thu Apr 01, 2021 10:07 am
That grid interactive stuff confuses the h-e-double-hockey-sticks out of me.
Me too! I wonder if a hybrid system like Enphase or Tesla with their "AC battery" backup is less fussy. It almost seems like there are too many bells and whistles in some of the OB systems.

But then there's the risk of not being able to do exactly what you want...

(Didn't intend to hijack the thread here, just thinking out loud.)
pss
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Re: Off Set Enable Question.

Post by pss »

To refresh, my system is GRID TIED SELL from 9 PM until 4 PM, then GRID ZERO from 4 PM to 9PM. So shortly after midnight last night, I looked at my inverter settings and the OFFSET ENABLE was switched back by software command coming from somewhere to OFFSET DISABLE (even though inverter status is GRID TIED). I put it back to ENABLE. This morning, my SOC began at 80% and voltage 49.8. As the sun rose, the chargers took over and completed a full charge cycle going through bulk/absorb and float. Selling began at about SOC 95%. When SOC hit near 100%, or maybe my FNDC parameters, the charge controllers went back to BULK from float or absorb (not certain). The reason I do not want my inverter charger ON is because I do not want it to charge my batteries when the electricity use cost is high and I get plenty of PV each day. However, I now know an event is occurring at MIDNIGHT changing the inverter OFFSET parameter. What I am going to try is to set my inverter charger to ON, but reduce my BULK voltage for the inverter to 47.2 volts. My batteries will stay above this and the grid protections are set anyways. So hopefully with the inverter charger kept ON, but the batteries always at voltage above the BULK setting, an inverter charge cycle will not take place (unless manually started) and the OFFSET will remain ENABLED. We shall see tomorrow.
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Re: Off Set Enable Question.

Post by raysun »

For we grid simpletons following along, does BULK in this context mean REBULK, or perhaps ABSORB? Or is there a BULK value that shows up during grid operations?
pss
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Re: Off Set Enable Question.

Post by pss »

For clarity purposes, BULK is the Outback Power term for let it rip charging, ie. the period of time of maximum amperage flow into the batteries. Chargers are often in the BULK phase even though the USER only sets a RE-BULK voltage parameter, not a BULK. When a point of resistance to amperage flow is reached, ABSORB charging is begun. This is pretty well defined and is the period of time the batteries should be held at a certain voltage during charging. FLOAT is also pretty well defined as the voltage the batteries should be kept at to complete their charging and provide current to a load. Outback even can provide continuous charging. If using PV, the FLOAT continues until there is no PV to maintain the battery voltage. As for the term RE-BULK, I am making the assumption that is used to signal the charger to return to the let it rip charge current if PV or AC is present before a charge cycle has completed entirely. Only RE-BULK voltages are set, not BULK and BULK has no timer setting. So yes, I reduced my RE-BULK value. Thanks for pointing out the need to clarify.
raysun
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Re: Off Set Enable Question.

Post by raysun »

RE-BULK is a tricky sucker. Ironically, it directly impacts ABSORB TIME.
fcwlp
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Re: Off Set Enable Question.

Post by fcwlp »

pss wrote: Thu Apr 01, 2021 12:14 pm To refresh, my system is GRID TIED SELL from 9 PM until 4 PM, then GRID ZERO from 4 PM to 9PM.
My error on switching to MINIGrid from GRID ZERO on the "test system." I can report that both MINIGrid and GRID Zero with the charger enabled work as one would expect. I will switch the "test system" back to GRID ZERO this evening and leave the charger disabled.
pss
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Re: Off Set Enable Question.

Post by pss »

Friday morning update. So after my system switched back to grid tied at 9 pm, the inverter's charger began charging the batteries. SOC was 80% and voltage 48.8 I manually stopped the charge cycle. I then noticed that the batteries had touched a voltage of 48.2 and this was below the inverter's RE-FLOAT setting, but above the RE-BULK setting. This morning, the OFFSET was DISABLE. So I have lowered the RE-FLOAT voltage to 47.2 and and changed the OFFSET to ENABLE and will observe again tonight.
fcwlp
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I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
Location: 80 miles NE of Phoenix at 5500'

Re: Off Set Enable Question.

Post by fcwlp »

My "test system" performed as one would expect. Batteries dropped to 93% (during the Grid Zero time), used grid remainder of night and batteries were charged by PV first thing in the morning and then it started to sell. Attached are the printouts of the settings for Mate3s, FM100 and 8048A.

Pete
2021-04-02 Mate3s Settings.pdf
(90.21 KiB) Downloaded 8 times
2021-04-02 FM100 Settings.pdf
(86 KiB) Downloaded 5 times
2021-04-02 8048A Settings.pdf
(92.24 KiB) Downloaded 5 times
pss
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Re: Off Set Enable Question.

Post by pss »

I reviewed your settings. The thing I am try to avoid is this: If my settings are like yours, but I have 3 separate arrays and charge controllers, and I keep my inverter's charger off, then the chargers begin in the morning to perform a complete charge cycle before selling. EXCEPT, I am starting with an SOC of 80% which equates to about 10 kW of battery power needing to be replaced. This winds up taking until about 11AM to Noon. Then as the chargers complete their times, they can go into a SILENT mode in which case no PV is harvested in the bright sunshine. This SILENT mode as I understand it is the period of the timer being completed and then the voltage drop from ABSORB to FLOAT and FLOAT to RE-BULK or RE-FLOAT. The 3 chargers do not act in concert with respect to their charge timers. The net result is that for all of the chargers to go into BULK/OFFSETTING and SELL the day is often after 12 noon. And the amount of PV harvested because of the chargers having SILENT periods and different stages of chare amperage results in a loss of about 10-12 kW of PV harvest. If OFFSET were to REMAIN ENABLED after the MIDNIGHT SOFTWARE switch to DISABLED, then the chargers would begin in the morning with maximum PV harvest and selling. They may not reach their full charge voltage until GRID TIE after 4PM (there is still enough PV to do this), but they reach their full amperage early in the day.

The Radian manual says that a charge cycle begins for very nebulous reasons, but it does say that a change in connectivity to the grid is enough to initiate an inverter charge cycle. This apparently included going from GRID ZERO to GRID TIED.

TO REFOCUS, I AM TRYING TO FIND A COMBINATION OF SETTINGS WHEREBY OFFSET ENABLE WILL NOT BE DISABLED BY SOFTWARE AT MIDNIGHT EVERYNIGHT AND THE INVERTER'S CHARGER WILL NOT BE TRIGGERED TO START A CHARGE CYCLE UNTIL THE PV CHARGERS START UP IN THE MORNING. AND WHEN OFFSET IS DISABLED, THE PV HARVEST IS TOO LOW TO JUSTIFY WASTING 10 kW OR MORE JUST TO GO THROUGH A 10 kW BATTERY CHARGE AND EXPERIENCE THE "SILENT" PERIODS OF THE CONTROLLER SOFTWARE. NOW I KNOW THAT THE SILENT PERIOD IS ELIMINATED BY CHECKING THE 24 HOUR CONTINUOUS CHARGE MODE, BUT I HAVE NOT YET USED THAT ON THE INVERTER.
pss
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Re: Off Set Enable Question.

Post by pss »

So it is now after 9 PM. My inverter is now grid tied and no longer grid zero. My battery voltage during grid tied dropped to 48.3. My SOC dropped to 81% from 100%. My load is 2900 watts being supplied by the grid and the inverter's charger, while enabled has not initiated a charge cycle. INVERTER OFFSET ENABLE IS YES. So now I will wait to see whether or not the software switch in the Mate 3S or Inverter turns off the YES flag for OFFSET ENABLE at midnight. I want it to stay on.
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I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
Location: 80 miles NE of Phoenix at 5500'

Re: Off Set Enable Question.

Post by fcwlp »

pss wrote: Fri Apr 02, 2021 7:36 pm Then as the chargers complete their times, they can go into a SILENT mode in which case no PV is harvested in the bright sunshine. This SILENT mode as I understand it is the period of the timer being completed and then the voltage drop from ABSORB to FLOAT and FLOAT to RE-BULK or RE-FLOAT. The 3 chargers do not act in concert with respect to their charge timers. The net result is that for all of the chargers to go into BULK/OFFSETTING and SELL the day is often after 12 noon.
On your CCs, do you have "Grid-Tie Mode" enabled (Misc tab of CC in OpticsRE)?
pss wrote: Fri Apr 02, 2021 7:36 pm The Radian manual says that a charge cycle begins for very nebulous reasons, but it does say that a change in connectivity to the grid is enough to initiate an inverter charge cycle. This apparently included going from GRID ZERO to GRID TIED.
If I have the Radian's charger enabled, as soon as the system switches from "Grid Zero" or "Mini Grid" in the evening, a charge cycle is started. I have seen this happen when the SOC is in the low 90s to the 60s.
pss wrote: Fri Apr 02, 2021 7:36 pm TO REFOCUS, I AM TRYING TO FIND A COMBINATION OF SETTINGS WHEREBY OFFSET ENABLE WILL NOT BE DISABLED BY SOFTWARE AT MIDNIGHT EVERYNIGHT
I have never seen this happen with current configurations. On the Mate3s "Global Charge" tab, your "Auto Grid-Tie Mode" should be disabled. When "Auto Grid-Tie Mode" is enabled "Offset" is disabled at midnight each night. It seems logical that "Auto Grid-Ti Mode" should be enabled but, I have found it is best to keep it disabled.
pss
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Re: Off Set Enable Question.

Post by pss »

Thanks to all who are contributing and following.

My chargers are all GRID TIED ENABLED.
It was mentioned that the inverter's charger will charge with SOC of 60-90 percent. It appears from my experiments that the inverter's charger has a charge cycle triggered by the RE-BULK and RE-FLOAT voltage settings of the inverter's charger. So if you lower your RE-BULK and RE-FLOAT settings to below what your batteries will reach when in Grid Zero (not sure about Mini Grid), and then GRID TIED is restored, the charger will not initiate a charge cycle if the batteries never reached the RE-BULK or RE-FLOAT voltage, maybe regardless of SOC.

Lastly, my Mate 3S settings did have AUTO GRID TIE ENABLED. Today, I will set this to DISABLED. This should be the final piece of the configuration settings to maximize sell and PV charging and to minimize inverter charging and SILENT charger modes. Maybe maximum PV harvest is not a dream after all?

The only caveat of this setup is to make certain according to your battery type that you equalize according to manufacturer's schedule. So you will have to get batteries to 100% and then initiate a manual inverter charge equalization at a day and time of your choosing.
pss
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Re: Off Set Enable Question.

Post by pss »

Success!
With auto grid tie disabled, the system now performs ideally.

Yesterday, my batteries discharged to 76% SOC and 48.2 volts while on Grid Zero. With the inverter's charger set to ON,, with the GRID TIED state returned, no inverter charge cycle took place. This morning, the PV chargers started in BULK and inverter offset was working perfectly. Now the only tweaking left to do is to adjust the sell voltage so that the battery bank gets to 100% SOC from PV in the day and to observe peak voltages reached.

The net effect of all of these changes is to avoid grid use with high TIME OF USE PRICES, avoid charging from the grid with so much PV available, safeguard the battery bank and maximize SELL to the grid.
fcwlp
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I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
Location: 80 miles NE of Phoenix at 5500'

Re: Off Set Enable Question.

Post by fcwlp »

pss wrote: Sun Apr 04, 2021 8:27 am Success!
With auto grid tie disabled, the system now performs ideally.
Congrats
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