'Off-Grid' meets 'Grid' - Sort Of - SkyBox Installed ? ** victron ESS Dilemma**

[Snapperhead]

Hi All..... Finally had my new SkyBox (Not Outback Skybox) installed on the rear studio at the rear of my home. My aim is to eventually go "off-grid" and this is my first step in getting my head around a new area of electronics and exploring how it all plays together. (See Photo's)

The Setup >> Skybox (Sky Energy) Containing:

Multiplus II 48v 8K/110 230v
MPPT RS 450/100 Tr (connected via VE-Direct)
2X BSL LiFePo4 48v 100 Ah 5.12 kWh (connected via CAN-bus) with their own BMS and passive balancing.
Cerbo GX
Victron Energy Meter (ET112) on MCB of house between MPII AC-In <> Grid
14x Kookuburra 415w Panels (5.81 kW)
This is all configured on a rear studio (with sub board x2) that is connected over 50 Metres away via a single cable from Multiplus AC-In to the main switchboard on the house loud bus (See diagram).

Also on the main switchboard is an AC-Coupled GoodWe MS-10kW Inverter (with HomeKit Smart Meter on MCB at grid feed-in point) fed by 18x 440w Jinko Panels (7.92kW).

There is also a Blue Diamond 6.5kVa diesel Gen7S connected as backup on the MCB through a 63A Auto T/fer Switch (See Diagram).

My three(3) Questions to this amazing group are as follows:

1. The Skybox somehow all plays nicely together with the house, except I'm yet to understand or configure the skybox to be able to contribute to the main house loads. (Connected parallel with Multiplus AC-In _ See Diagram) I'm told this is possible and should be happening, however, it's not..... In fact the grid appears to be trickle charging the battery's at night time and also feeding the Multiplus connected AC-Out 1 (Critical Loads) during the night, and not the battery's as planned. The battery's remain 'idle' most of the time, unless the Critical Loads go very high and they then they share the load with the DC-Coupled PV if there is any, and the grid.

2. It's configured with an ESS Assistant, however I don't fully understand all the settings within that Assistant. The mystery "Grid Set Point" appears to do absolutley nothing under any circumstances, however maybe it's not supposed to ? I need some clarity around when and if this 'Set Point' is relevant and when it kicks in. I understand the bi-directionality of it and it's basic purpose, but don't know when it's supposed to work and not work.

3. I'm told that in my current setup, my LiFePo4 batteries will not be able to have or maintain a 'float voltage' and that there will just be one single charge voltage.... that will then absorb for a period of time at a certain current threashold. Is there any way to overide this and have it float at a lower voltage when the battery's are not in use (i.e. small loads with excess DC-Coupled PV energy available) ?

Thanks in anticipation of any advice ?

 

[timselectric]

Wholly cow, I don't even want to know what that thing costs.

 

[Snapperhead]

Wholly cow, I don't even want to know what that thing costs.

Yep.... It's all good. I sold two of my firstborn children to pay for it !!.... Now I have two empty bedrooms for workshops and storage

 

[timselectric]

For Victron questions, @sunshine_eggo is your guy.
I'm sure that he will help you figure things out.

 

[sunshine_eggo]

@Snapperhead

ESS is not in my skill set - only concepts.

4. Configuration

www.victronenergy.com

Grid set point is about when to draw from the grid in self consumption mode.

I think you want Grid Feed-in.

AC coupled PV refers to a separate GT inverter AC coupled to the MP. If you don't have a separate GT array, this is off.

DC coupled PV would be the Cerbo attached Victron MPPT(s). Enabling this would allow any surplus PV be fed back through AC in.

If surplus PV has the potential to exceed house loads, it could backfeed all the way back to the grid.

Recommend you read that entire online manual, print out the PDF and sleep with it under your pillow.

 

[Snapperhead]

@Snapperhead

ESS is not in my skill set - only concepts.

4. Configuration

www.victronenergy.com

Grid set point is about when to draw from the grid in self consumption mode.

I think you want Grid Feed-in.

AC coupled PV refers to a separate GT inverter AC coupled to the MP. If you don't have a separate GT array, this is off.

DC coupled PV would be the Cerbo attached Victron MPPT(s). Enabling this would allow any surplus PV be fed back through AC in.

If surplus PV has the potential to exceed house loads, it could backfeed all the way back to the grid.

Recommend you read that entire online manual, print out the PDF and sleep with it under your pillow.

Hahaha Yes, it's an uncomfortable pillow, but I feel like I've read it back to front now ! It is slighlty ambiguous and not greatly worded.... so has added to my confusion a little.

I can't seem to get this setup to contribute to the house loads even when using "DC Coupled Grid Feed-In" option with the "Grid Setpoint" at an appropriae Negative (-) value..... I wasn't sure if this was even possible with my setup. Hence the ESS question. Hopefully some ESS guru will trip over my post

I do notice the Multiplus drawing from my home excess solar (AC-Coupled GoodWe) to power it's critical loads and charge the battery's.... and keeps the import<>export very close to Zero on sunny days. Just can't seem to get it to feed any power back into the house loads ?‍

 

[timselectric]

I'm strictly an off grid guy.
But for exporting, you usually need CT's to monitor the flow of current in and out of the system.
Where they are located, determines where the power is controlled at.
Do you have them, and where are they located?

 

[Snapperhead]

I'm strictly an off grid guy.
But for exporting, you usually need CT's to monitor the flow of current in and out of the system.
Where they are located, determines where the power is controlled at.
Do you have them, and where are they located?

Yes, I have the Victron ET-112 installed at the Grid entry point that is wired directly to the Multiplus.

 

[timselectric]

Yes, I have the Victron ET-112 installed at the Grid entry point that is wired directly to the Multiplus.

I believe that you need to move them to ahead of the main panel. This allows them to see only what is actually exported to the grid.

 

[Snapperhead]

I believe that you need to move them to ahead of the main panel. This allows them to see only what is actually exported to the grid.

Yes, sorry for any confusion, the Meter is installed right at the end of the supply, between the Main Switchboard and the Grid Supply Smart Meter. So it is literally at the gateway to the grid.

 

[timselectric]

Well, that's all I've got.
Sorry

 

[sunshine_eggo]

If you don't already have an account on the professional site, now is the time:

ESS training video:

Victron Energy - Victron Professional

professional.victronenergy.com

Assistants in general with a brief bit on ESS:

Victron Energy - Victron Professional

professional.victronenergy.com

 

[Consumerbot3418]

I've been using ESS for several months now. Completely off-grid, but my Victron system is fed by a pair of Sunny Islands. ESS works (for me) more or less exactly as advertised. It targets that value, and either pulls or pushes that amount of power from the AC input. In a situation where loads are higher than the inverter can output, it will grab the difference from the grid--so the setting is a just a target. It does have some latency as loads switch on and off, but after a few seconds, it does settle at the target. Obviously, when the battery is full, it stops grabbing from the grid. And when it's empty, it starts pulling, according to the SoC minimum setting.

I'm not using an external CT at all. My Multis (split phase) built-in CTs are used to measure (off) "grid power". There's a parameter you can set for where it sources the power measurement: under ESS, "Grid Metering".

The only issue I've had is that, at times, ESS seems to conflict with DC coupled PV. If the battery is full, and ESS is set to a too-high setting, PV isn't backfed. I've yet to figure out exactly why that might be, and it's only a minor nuisance.

I think your mode needs to be set "on", not "inverter only" or "charge only". Beyond that, it should start pulling/pushing power from/to the AC input, so long as the battery SoC isn't confounding matters.

The only other "gotcha" I can think of is the ESS mode selector--I'm using "optimized without batterylife". If you're using "keep batteries charged", I'd expect that might prevent it from feeding power into the grid. You might also want to make sure ESS->Grid Feed-in->"DC coupled PV feed-in excess" is enabled! Do you have working communication between the Cerbo and the MPPT? My MPPT shows up on the main menu of the Cerbo, and the state is "Ext control".

To answer your second question, your system can certainly be programmed to float at a lower voltage. To my knowledge, that's something that has to be done with the Windows software and MK adapter--it's not an end-user accessible setting.

I'm no expert, but I do have the real-world experience of building and programming my own system, and I'm happy to help within my limited capabilities.

ps - off-topic, but this is the first time I've seen an emoji in the URL bar of my browser... ?

 

[Snapperhead]

Thanks for your input 3418 There is much to learn about the ESS environment. It does draw from the grid effectively, and finds an almost zero balance between import/export when supplying the Multiplus loads and charging.....It's just the other way around it appears stuck. I have the Multi constantly on "Inverter" mode and also "Optimized - Without Battery Life" by default. And when playing with the "DC-Coupled Grid Feed-In" setttings and a negative (-) Setpoint I still cannot get it to feed-in to the house loads from the Multi AC-In. It's a Mystery

 

[sunshine_eggo]

To answer your second question, your system can certainly be programmed to float at a lower voltage. To my knowledge, that's something that has to be done with the Windows software and MK adapter--it's not an end-user accessible setting.

Not if the BMS is in control of the system. The BMS is mandating a "charge voltage limit"

Thanks for your input 3418 There is much to learn about the ESS environment. It does draw from the grid effectively, and finds an almost zero balance between import/export when supplying the Multiplus loads and charging.....It's just the other way around it appears stuck. I have the Multi constantly on "Inverter" mode and also "Optimized - Without Battery Life" by default. And when playing with the "DC-Coupled Grid Feed-In" setttings and a negative (-) Setpoint I still cannot get it to feed-in to the house loads from the Multi AC-In. It's a Mystery

Is the inverter grid code set to your region?

 

[Snapperhead]

Is the inverter grid code set to your region?

Yes, the Grid Code was pre-installed in the ESS by the Installer… Info regarding the Grid Codes is hard to find, and appears to be held in trust by some secret society of engineers .! Haha

 

[sunshine_eggo]

Yes, the Grid Code was pre-installed in the ESS by the Installer… Info regarding the Grid Codes is hard to find, and appears to be held in trust by some secret society of engineers .! Haha

It's reported openly via the Grid tab in VEConfig.

The password to change that grid code is indeed a closely guarded secret.

At this point, it would seem prudent to seek support from the supplier providing the Victron equipment.

 

[Snapperhead]

It's reported openly via the Grid tab in VEConfig.

The password to change that grid code is indeed a closely guarded secret.

At this point, it would seem prudent to seek support from the supplier providing the Victron equipment.

Thanks, yes I’ve been reading till my eyes bleed ? There isn’t a lot of easily obtainable info on the individual attributes of individual codes. Even though I have the password, installers are very reluctant to experiment or test code variants, and even less so with end-users, despite a solid understanding of electronics.

I’m hoping someone has encountered a similar dilemma and found a healthy work-around ??????

 

[Consumerbot3418]

Sorry for the late response--I miss the email notifications we used to get on this site!

I've only just been able to look at your schematic. I haven't played with AC coupled PV with Victron (yet). But it appears you aren't really doing that, anyway... AC PV goes to your house loads, and extra gets dumped to the grid, right? And if there's a grid outage, it's dead in the water?

So, like @sunshine_eggo said, you definitely have to have the right grid code. But unless I'm mistaken...

I have the Multi constantly on "Inverter" mode

This could possibly be your issue. Have you tried setting it to "on"? I start getting confused, because there's a hardware switch on the unit itself, and another one in software. I'd give both a try.

Forgetting the DC PV, you ought to be able to backfeed the AC input by simply putting a negative number in. Are you sure that isn't happening? Based on your schematic, it looks to me as if you ARE feeding your house loads if you reach a measurement of zero at the ET-112. If you look at VRM (especially the advanced tab), there's incredibly detailed data. I'd imagine it should show inverters generating more power than is consumed by your critical AC loads--those would be the house loads. A negative value in ESS (using the ET-112 for metering) would actually be targeting backfeeding the grid itself, above and beyond your house loads... right? Is that your intention? Is it possible that you're set up for zero export?

I don't have experience with external metering, I'm out of my depth. Be curious to know your resolution, if/when you find one. Might also be worth mentioning that generators usually don't like being backfed. If you lose power and switch to genset, your ET-112 is out of the loop, too? Hopefully that's been accounted for in the design.

 

[Snapperhead]

Sorry for the late response--I miss the email notifications we used to get on this site!

I've only just been able to look at your schematic. I haven't played with AC coupled PV with Victron (yet). But it appears you aren't really doing that, anyway... AC PV goes to your house loads, and extra gets dumped to the grid, right? And if there's a grid outage, it's dead in the water?

So, like @sunshine_eggo said, you definitely have to have the right grid code. But unless I'm mistaken...



This could possibly be your issue. Have you tried setting it to "on"? I start getting confused, because there's a hardware switch on the unit itself, and another one in software. I'd give both a try.

Forgetting the DC PV, you ought to be able to backfeed the AC input by simply putting a negative number in. Are you sure that isn't happening? Based on your schematic, it looks to me as if you ARE feeding your house loads if you reach a measurement of zero at the ET-112. If you look at VRM (especially the advanced tab), there's incredibly detailed data. I'd imagine it should show inverters generating more power than is consumed by your critical AC loads--those would be the house loads. A negative value in ESS (using the ET-112 for metering) would actually be targeting backfeeding the grid itself, above and beyond your house loads... right? Is that your intention? Is it possible that you're set up for zero export?

I don't have experience with external metering, I'm out of my depth. Be curious to know your resolution, if/when you find one. Might also be worth mentioning that generators usually don't like being backfed. If you lose power and switch to genset, your ET-112 is out of the loop, too? Hopefully that's been accounted for in the design.

Thanks for your reply 3418,

Yes, my AC-Coupled setup is just a pre-existing system in parallel on the AC-In of the Multiplus.... and just feeds the house loads, then exports all excess (5kW Max Export here in Australia). I notice this AC-Coupled PV Inverter does assist with the Critical Loads AC-Out_1 of the Multiplus during high loads, but only until the Battery / Inverter catches up, or batts drain to the minimum SoC... this PV excess and grid then takes over all those loads.

The Multiplus manages to maintain a very close Zero Export/Import at the grid point (ET-112 Meter) when the AC-Coupled PV Excess is assisting the charging of the battery's in partnership with the DC-Coupled PV first thing in the morning. (See PV/Load curve pic)

I just cannot seem to get the Multiplus to feed back the other way at all to assist with the house loads. Sorry for mis-understanding @Consumerbot3418 but the Multiplus is manually set to "ON" which I understand is Invert & Charge. Within the Cerbo it is also activated (see setting pics). Also I've attached a current (right now) Screen Shot whilst at night time with no PV that illustrates the Multiplus not helping the loads at all, even when the loads are small and the grid Setpoint set to varying numbers between -50 to -500 Watts. Thoughts ?

P.S. Yes the existing AC-Coupled PV does Anti-Island immediately during a LOM grid failure, at which time the ATS will kick in once the Genset starts up and feeds it's AC to the house loads >> this is the topic of another thread in the Victron Community as I was also concerned about how the Genset will play with the Multiplus...... But it appears not to at all. As the Multiplus also Anti-Islands and continues to see the Genset Output as a LOM. So that's perhaps another curios topic, as I was also concerned how they'd ineteract on AC-In of the Multiplus. So far I have had conflicting advice from all channels. But this is a separate issue and I dont' want to muddy the waters ?