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solarlion avatar image
solarlion asked

ESS – What Multiplus II 5000 / EM24 Ethernet regulation speed expected?

I installed a system with 3-phase Multiplus II 5000, 8x Pylontech US3000C and a EM24 Ethernet as grid meter. There is an AC coupled Solar system.

The EM24 should have a measurement speed of 1600 data points per second in 50Hz System. But the ESS seems to take multiple seconds to adopt to a new load. It does not matter if the Solar peaks or if I activate a big consumer.

Following Picture show the Grid consumption and the spikes trying to regulate it to Zero.ess-regulation-speed.jpg

Now the Question:
Is this normal? Any settings to improve the regulating speed of ESS?

Multiplus-IIESSPylontech
ess-regulation-speed.jpg (202.6 KiB)
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12 Answers
mucwendel avatar image
mucwendel answered ·

I have the same Problem.

It takes sometimes more than 10 Sec. until the power comes back from -xxx to positive values.

That means I give away power for free.

It happens e.g. using induction heater on 50% as it switches on and off 0/3000W.

Some say it belongs to Grid Code. But nobody prevents me to switch of and on 3000W the whole day. But MP2 is very slow :-(.

(AUX-1 is not used)


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shaneyake avatar image shaneyake commented ·

The inverter is limited to 400W per second at the fastest but there are also other factors. See link below.

https://www.victronenergy.com/live/ess:ess_mode_2_and_3
"5. Response times and ramp speed
There are multiple factors that determine the response time to a (digital-) command to feed in:

Latency and communication speed of all components in the communication chain: ModbusTCP or MQTT, GX Device, MK3 microprocessor, ESS Assistant, internal communication in the Multi itself.

Rate limiting imposed by the used Country Grid code. Code “Other” has no rate limiting, Code “Europe” allows installer configurable rate limiting, many other codes have fixed a powerup ramp up.

Hard coded rate limiting in the inverter/charger firmware: as per ESS version 162 it is set to 400W per second. The reason for this rate limiter is that without that there are regulation problems (overloads and such) when the mains is weak (long cables and such resulting in a relatively high impedance). More information on that here, as well as in the main ESS manual."


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mucwendel avatar image
mucwendel answered ·

It looks like the regulation of the battery charging/discharging is too slow. When nI switch off a 2kw heater it takes up to 10 sec. to 0 infeed.


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David avatar image David commented ·
This is by design.
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pedaaa avatar image
pedaaa answered ·

there are some topics about this "issue"

Some say, the solution is, to but all loads to AC out.

loads on AC in will be handles very slow.


others say, once an EM24 grid meter is installed, its slow anyhow.

Sadly i dont know yet myself, as my installation is not finished yet. But i would also have an EM24. So... if you have more news or information on this, i would be happy, if you let me know.

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shaneyake avatar image shaneyake commented ·
Correct if you put the load on the AC_Out it will be handled by the inverters internal control loop which is much faster than the ESS control loop running on the GX.

The inverter still has a max ramp rate but it is still pretty fast.

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pedaaa avatar image pedaaa shaneyake commented ·
thanks for this answer. I ask myself the following:

In my case, i would have EM24 (RS485), some loads on AC-in, most of the loads on AC-Out1 and some on AC--Out2

So....

the loads on AC-in would be handled slower, correct?

But AC-Out1 and AC-Out2 should react quite fast, corrct?



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baxter avatar image baxter pedaaa commented ·
AFAIK, in case an energy meter is used and configured in the ESS setting, the internal control loop of the MPs is not used, even not for loads on ACout? Maybe someone can comment on that?
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pedaaa avatar image
pedaaa answered ·

ah, one other point:

changing the grid set point to a small negative number might also help?!

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shaneyake avatar image
shaneyake answered ·

The ESS control loop is normally 1 - 5 seconds but there is a ramp rate it won't exceed so can take longer with big loads. This is normally not a problem as it averages out and most grid meters only report total energy used in 30min windows.

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pfuhu avatar image
pfuhu answered ·

I was actually concerned about this at well at the start. On the power consumption meter from my (belgian) energy supplier, I would also see a continious delay. Mostly, this is limited within the range of -40 to +40 watt, but in case of high loads (for example 2000 watts), the reaction seems to be quiet slow as described above.


However, when I look at the actual consumption/injection per day which is registered by the electrical company, it is limited (in my case on the worst days) to maximum 400Wh of injection and the same amount of consumption each day.. I also have days of only about 200Wh.


I have my grid feed value set to 0w. You could always adjust is to limit consumption or injection even more in one direction ...


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mondeoman avatar image
mondeoman answered ·

I recently installed an ESS for the whole house. All loads and the PV inverter are on AC IN (Grid Parallel topology).I'm using the EM24 RS485 grid meter.


I also noticed the slow response time of the ESS, but after 10 days the billing energy meter has registered only 5 kWh (average of 0.5 kWh per day), for about 200 kWh energy used inside the house.


So I'm not concerned and I don't consider this as a problem.

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mucwendel avatar image
mucwendel answered ·

btw. I have a ET340 and some people saying the EM24 should be better for ESS. But if the EM24 also reports wrong values it make no sense for me to change.

Lets see what the supplier grid meter reports after they have changed from the old Ferraris (no return lock ;-) to the new electronic grid meter.


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shaneyake avatar image shaneyake commented ·
The response time of the ET340 and EM24 are basically the same.


Both of them report the correct valves, just handle 3 phase reporting differently.

If you are getting wrong valves from the meter then your settings are wrong or the meter is broken.

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larsea-dk avatar image
larsea-dk answered ·

Hi

I also have the problem. It is especially a problem when my battery actually is full and i have days with shifting solar power... cloud, full sun, cloud etc. Then since it reacts slow I even get:

Cloud to full sun: Way too much solar power and it goes to battery due to slow ramp up Multiplus

Sun to cloud: Actually not the biggest problem, but the multiplus do not decrease export as fast, so it will take power from battery. This lowers the battery voltage so much, that the system thinks the battery voltage is so low, so it can allow to charge at very high current again when sun comes back. This just gives an issue, since high currents to a full battery gives high voltages...leading to over voltage protection.

Solution is of course to lower Full voltage value, but then I'm decrease my battery capacity due to a slow Victron System. I have heard that an external Amp-clamp can be placed on AC-in side and connected to the MP2...but is this correct??

BR,

Lars


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shaneyake avatar image shaneyake commented ·
What type of battery do you have?


Everything you are describing here should actually be handled by your MPPTs and the multiplus/load being slow shouldn't be a problem.

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larsea-dk avatar image larsea-dk shaneyake commented ·

For me it just seems that the MPPT's are very fast reacting...which is of course good to maximize power from sun, but if my battery is already full and I'm feeding excess to grid, I expected...or at least it could be great.. that the multi reacted almost just as fast as the MPPT's. But it seems to be coded i firmware to only adjust 400w/s, which is quite long if you go from 1000watts to 4200watts in a second on the MPPT's. That is much power going to a "full" battery. But yes, I can just lower the "full" limit of my battery, so I have space for this. But over a day, this seems for me to be an issue anyway. I have lowered my voltage 0.3volts on my lithium battery. But the case is just, I really cant see why the Multi is set to act that slow...simple question -> why??

What do you think the MPPTS should do?? If over-voltage they cut of quite fast, making batteryvoltage go fast down, since the MP2 due to low ramp down suddenly draw power from battery to grid...which gives quite fast a voltage drop so much, that the MPPTs boost extremely fast up again...and now the MP2 has ramped down and goes slowly up again. Seems a bit of wrong regulation, or maybe there is just something I have missed or didn't understand.

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shaneyake avatar image shaneyake larsea-dk commented ·

When ESS is running the MPPT's should say external control.
They will normally just hold the bus voltage at MAX_VOLTAGE+0.1V
The multiplus then tries to keep the bus at MAX_VOLTAGE, this mode is called Overvoltage feed-in and is used when the battery is full.

The mppts do really fast regulation to keep the bus at MAX+0.1V, the bus may drop below MAX for small amounts of time but should never go above MAX+0.1.

This regulation is done on the multiplus and doesn't use the grid meter. If you have zero-export or a feed-in limit then it will need to use the meter data but that typically just sets an inverter power limit but the bus is still held at MAX+0.1V by the MPPTS.

It sounds like your MPPT's and inverter aren't all communicating properly or you aren't using lithium batteries.

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larsea-dk avatar image larsea-dk shaneyake commented ·

Thank you for reply :-) and great to hear that there might be a solution.

The mppts are controlled externally and follows at the moment the BMS. The BMS is set at 57.1volts (which is 4.08v per cell and max is 4.2v) for my setup, which is the reason why I set alarm for the shunt at 57.4volt (4.1volt). I can get overvoltage alarm when mppt charge shifts due to clouds.

So

1)for my nissan leaf cells I go to 4.08v (57.1v) to ensure range to the 4.2v absolute max voltage(58.8volt), should I just increase my alarm limit?

2) I have derated my MPPT's ( 2x 250/100) from 100A to 38A each, since I only have one Multi to convert/feedin to grid when there is excess. This is due to I have heard AND experienced that the MPPTS will just keep on charging eventhough I'm at 57.4volts. They simple do not ramp down eventhough me max voltage is 57.1v (by BMS).

3) just for a note: I'm soon going to convert to LiFePo4 cells 18s, but this has nothing to do with how the system works...just new settings.

1x MP2 48/5000, 2x MPPT 250/100, 500A shunt, Raspi VenusLarge (w.NodeRed)

7.5kWp PV array (10x for MPPT1 and 8x for MPPT2)

10kWh nissan leaf (going for 18s 280Ah LiFePo4 soon)

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thomas-pv avatar image
thomas-pv answered ·

I also have EM24 ethernet and external PV inverters and it takes until 3 to 5 seconds to reach the gridpoint setting. So every day goes 0.1 until 0.2kWh to the grid.

But I can bear it ;-)


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mhinz76 avatar image
mhinz76 answered ·

To my understanding that is normal behavior, it is called at least in German Tot- und Einschwingzeiten. They can vary from system to system from almost 0 sec to 11 sec! see study of HTW Berlin: https://solar.htw-berlin.de/studien/speicher-inspektion-2022/

1695105299619.png

The Totzeit (death time) is the time until the system starts reacting on a power consumption change, the Einschwingzeit (balancing time) is the time until it zeros out the grid consumption.


1695105299619.png (27.1 KiB)
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larsea-dk avatar image
larsea-dk answered ·

In Denmark we used to pay/get paid based on hourly summation. But as I understand it at least, we will from january 2024 for solar system endusers going to pay for our immediate use. So it might become important to improve the response time.

For now I have grid parallel setup and can easily see the slow response..on the VRM at least.

It should be due to some EU regulations, so I guess most of you will also go from hourly pricing to immediately pricing(or whatever it is called :-)


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solarlion avatar image solarlion commented ·
Germany is since ever on this pricing sceme. You pay everything whats going from and to the net. No summations at all, even millisecond spikes need to be payed. Heard the first time that from this summation, so thank you for sharing this info.
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