question

Philipp Trenz avatar image
Philipp Trenz asked

EM24 on VRM for consumption forecast?

Hey there,

I'm currently planning a grid-connected UPS solution for a NGO in the Peruvian Andes, for which I work on a voluntary basis. Main goal is to secure some security and IT appliances (single-phased) in the case of power outages. The system will consist out of 3-7 kWh LiFePo4 48V batteries, a Multiplus-II (probably 3kVA) and 2 to 4 kWp of solar via an MPPT controller. And a Cerbo GX as the heart of the system.

As we are also planning to get a larger (3-phase) generator or battery setup to support the whole complex (4 buildings) later on, we want to record our exact overall consumption data so that we can then size the system sensibly.

Also, feeding energy into the local grid will probably not be possible. But of course we're interested in consuming our solar-generated energy also by devices not directly connected to the Multiplus-II.

So I have some questions to better understand the system options:

  1. Is the consumption of surplus electricity "before" the Multiplus possible without grid feeding with an EM24 or similar?
  2. Can the logged data from the EM24 be exported stand-alone from the VRM portal for analysis on mean and peak consumption?
  3. If not, is there anything against connecting the EM24 via RS485 Modbus to another data logger besides the Cerbo GX to collect the data elsewhere?
  4. Are there compatible alternatives with > 65A?

Thanks a lot in advance!

VRMEnergy Meter
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

3 Answers
shaneyake avatar image
shaneyake answered ·

1. Yes, when ESS is running the inverter will try to cover all loads from the meter on. So both loads on the input and output of the inverter. However you will get some very short pulses of feedback to the grid.

2.You can download the data from VRM as kwh per phase or w averaged over a minute per phase.

3. yes, if you run the large firmware you can access it from in NodeRed and log it to file or somewhere else. Also the meter data is available from the GX via Modbus TCP

4. The EM24 is available in a CT version that can be used on system of 1000s of amps.

I personally would not use the Ethernet Version of the EM24. There has been a lot of reports of it locking up and having other issues. We have used the RS485 version in a lot of installs with no issues.

3 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Philipp Trenz avatar image Philipp Trenz ♦ commented ·
Hey @shaneyake, thanks a lot for your detailed and very helpful answers! Especially for the hint with the EM24, we'll use the RS485 variant then.

One last question: What does "large firmware" mean, is there another firmware branch with additional functionality? I wasn't able to find find further information to this.

0 Likes 0 ·
shaneyake avatar image shaneyake Philipp Trenz ♦ commented ·

No Problem,


To clarify Meter data and a bunch of other parameters are available via Modbus TCP from the GX on both firmwares.

The large project, linked below is still technically in Beta, but I have been using it for a long time with no problems. Main limitation right now is that you can't remotely update the firmware. But it includes NodeRed and all the Nodes you need to interact with the Victron system. I also have InfluxDB nodes that log to my server.
https://www.victronenergy.com/live/venus-os:large

0 Likes 0 ·
Philipp Trenz avatar image Philipp Trenz ♦ shaneyake commented ·
Oh, awesome. Many thanks for this explanation!
0 Likes 0 ·
Philipp Trenz avatar image
Philipp Trenz answered ·

Oh, just figured out that the 65A limit of the EM24 is per phase.This makes question 4 obsolete ...

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Philipp Trenz avatar image
Philipp Trenz answered ·

Also able to answer the 3. question myself: Should not be an issue at all. Furthermore there is a Ethernet variant for the EM24 available, which talks Modbus TCP. That's awesome, so I can implement some additional logging of the consumption and power data using a combination of Grafana, InfluxDB and Telegraf with the Modbus Plugin.
So, two questions to go :)

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.