question

svet avatar image
svet asked

Inconsistent energy production and consumption readings

We're working with a couple of systems where the production and consumption readings in VRM don't really make sense - namely, for a given period, kWh consumed far exceeds kWh produced. I'd love to get a better understanding of what might be going on.

The composition of both systems is as follows:

  • Three-phase off-grid systems with PV + battery + genset
  • Battery inverters (6x): Quattro 48/8000/110-2x100 rev2
  • MPPT charge controllers (3x): SmartSolar Charger MPPT 250/100
  • PV inverter (1x): Fronius Eco 27.0-3-S
  • Diesel generator

The issue is that in the kWh Excel report (and also in the VRM UI), it appears that the energy delivered from the batteries is far greater than the energy going to them.

Example over a 30-day period:

  • PV to battery: 908 kWh
  • Genset to battery: 87 kWh
  • Battery to consumer: 1575 kWh

It's not clear where the extra ~600 kWh come from. It's obviously not just additional discharge of the batteries, which have a capacity of ~100 kWh. Also this kind of pattern – of consumption being greater than production – is repeated on a daily basis; i.e. it's not just a one-off data glitch.

Any ideas what the culprit might be? And in the meantime, any thoughts as to whether the production or the consumption values are likely to be more reliable?

Finally, besides the two systems that exhibit this issue, there is a third with the same composition, where the readings there appear to be more consistent. In that the energy delivered from the batteries is 70-80% of the energy going into them.

MultiPlus Quattro Inverter Chargerkwh
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4 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hello Svet,

From my experience investigating these sorts of issues, it is most often old firmware. That is certainly the first thing to check, and bring up to date before further troubleshooting.

Can you please check the firmware versions of the GX device, Inverter/Chargers and MPPTs and confirm their version numbers and that they are the latest available.

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svet avatar image
svet answered ·

Hi @Guy Stewart (Victron Community Manager) thanks for that steer. Let me check those (and potentially upgrade) and get back to you.

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svet avatar image
svet answered ·

Hello @Guy Stewart (Victron Community Manager), this is a very overdue response on my part – apologies. We did check on the firmware versions at the affected sites, and they do appear to be the latest (and auto-update is also turned on). Though the problem of inconsistent energy readings persists.

Namely, firmware versions in use are:

  • CCGX: v2.60
  • MPPTs: v1.54
  • Battery inverters: 430
  • BMS: v3.08

Any other ideas what could be the issue here? Could it be a potential complication due to the fact that there are also Fronius inverters and a generator on the AC bus?

Clearly, one of the following must be true:

  1. We actually have more energy going to the batteries than is being shown in VRM
  2. The energy supplied by the batteries is not as high as shown in VRM

It would be great to get to the bottom of this, as having accurate readings here is important for us. Let me know if there is any further info I can help with in this regard.

Thanks again,

Svet

3 comments
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Hi @svet,

Current Quattro battery inverter firmware is 475, not 430.

That would be the most likely cause, and first thing to bring up to date before further investigation.

This firmware update procedure has risks and is intended to be done by a technician with training and experience.


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svet avatar image svet Guy Stewart (Victron Community Manager) ♦♦ commented ·

Thanks for the catch @Guy Stewart (Victron Community Manager)! I did try to look up what's most recent there but wasn't able to easily find the info. We'll try to get this upgraded and report back.

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As it requires a specialised tool, and is intended for professionals, the information is only available via registration on https://professional.victronenergy.com to discourage people from attempting it before understanding the correct procedure and risks involved.

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machined avatar image
machined answered ·

I also have 3 Smartsolar units tied together and I noticed that they produce around 10% more power than what they are reading in my Cerbo. All have the newest firmware front to back. However, if I login the app I can see the unit is bringing in say 600 watts of networked power but the Cerbo will read 540 watts. The Cerbo is reading each Smartsolar incorrectly. This could be your problem too just amplified because of your system size.

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