question

ron-h avatar image
ron-h asked

Energy flows in VRM are incorrect

Do see an error in the energy flow calculations in VRM.

Own a 3 phase Multiplus II system and PV is injected at the AC1 out.
For battery monitoring I use a lynx shunt, so classic (off grid) install.

Grid power is connected but average power is near zero “ESS self consumption ”

Last hour PV production was 1,07 kWh and consumption 0,76 kWh.
Average AC in last hour was near zero (ESS, self consumption) so the difference between production and consumption should be “AC loasd “, correct?

1,07-0,76= 0,31kWh and this is a plausible value for mine AC loads.

In VRM the Installation data graphs show:

-System overview
Consumption 0,76 kWh
Solar 1,07 kWh
Battery average 64%
Battery nin/max 61%-67%

-Consumption
Fron solar 0,76 kWh

-Solar
Total 1,07 kWh
To Battery 0,31 kWh
Direct use 0,76 kWh

-Grid
To battery 0,04 kWh

In Dynamic ESS- energy

Solar to battery 0,31 kWh
Grid to battery 0,04 kWh
Total solar 1,07 kWh
Total consumption 0,76 kWh

The 0,31 kWh solar to battery is wrong!

According the linx shunt widgets around 0,8kWh would fit better.

So I think here are mistakes made in calculating the correct energy parts!
It should be:

0,31 kWh AC loads
and
0,76 Solar to battery

Can someone please investigate what’s wrong?

VRM
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.

5 Answers
JohnC avatar image
JohnC answered ·

@Ron_H

Try looking at your figures over a full day at least, or even 30. What the figures don't show is system losses, like inverter/charger, standby, battery roundtrip, etc. VRM doesn't attempt to define these, but in the washup they usually get lumped in as battery losses. So you might see your new super-efficient LiFePO4's bob with a 75% roundtrip efficiency. And complain..

But it's the whole system inefficiency. I can lose ~1.2kW a day from 5kW generation. Might seem a lot, but it's only an average like 50W continuously. Mine's a 48/5000 Multi, you have 3 phase but don't say what they are.

You need to look at this more broadly to nail down such a small 'deficiency'.

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.

ron-h avatar image
ron-h answered ·

Hi John,

Solar to battery value in the graph of 0,31kWh or 0,76kWh that's a huge difference and can't be explained by losses.

For some reason the power that’s going to the battery to charge it, is wrongly calculated.

Strange enough the power flows in dashboard realtime view and GX display are correct!
Just in “installation date” graphs they seem to be incorrect.

See pictures from remote console and VRM “Solar graph” a few days before.

The orange part should be solar to battery, and the blue AC loads.

Can someone tell me how VRM calculates consumption, maybe that’s wrong?

Is “consumption” the “AC load” than this value is incorrect, or is Solar – consumption the AC load, if no AC in is applied and system losses are zero?

The graphs need to be correct, this because next month I will use the system to dynamic buy and sell energy, prediction when to buy or sell will be incorrect this way!

Ron

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.

ron-h avatar image
ron-h answered ·

switched.jpg (240.2 KiB)
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.

ron-h avatar image
ron-h answered ·

Where can I lookup the definition of consumption.

In following example:

AC loads 0,3 kWh
Grid 0 kWh
PV inverter 2 kWh
Battery 1,7 kWh

What should be the consumption value 0,3 kWh or 1,7 kWh?

Ron

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.

ron-h avatar image
ron-h answered ·

Anyone?
If the power source is "Solar" only and I charge the battery with it, i see a consumption that is just the value lower as "AC loads" (consumption = Solar - AC loads).

Is this normal or should consumption be the "AC loads" only?
Solar is injected at multiplus II AC out side.

How is consumption defined?

How develops VRM and how can you get in contact with them?

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.