question

@zucca

We have the same system here. Well one of two - one charges for power going back, the other goes into tamper mode.

Your hard learned lesson on the grid set point is mentioned in the manual.

ESS by default not is not set to export to grid. (check on it anyway incase by accident it is enabled.) But you can get back shoot from overproduction when a load drops off. And a few other circumstances depending on your set up.

Usually the set point is at 50W (default). For some places it needs to be higher, it depends on what reactive power there is in the system.

Also different battery modes affect over shoot back to grid. You will have a learning curve for sure.

@Alexandra thanks for staying with me....

I suggest to mention in the ESS Manual what will happen to your electric bill in a not ESS net metering system: you pay also for the power feed back to to the grid.

More details in my case:

- ESS Feed into the grid is deactivated.

- two Quattro 10000VA in split phase config (USA)

- Metering is set to inverter as I have the grid on both AC1 inputs

- The grid and my home are energy neutral (W to grid=W from grid) when I set the ESS grid set point [GSP] to -30W

Now a couple of questions

1) To understand how much energy is exchanged in/to the grid I use VRM data in the (last) 24h

There ones:

Is there a better method?

2) My strategy now is to increase the ESS GSP until the above kWh number to the Grid is zero or slightly above zero....

3) I need the grid only in low SoC (10% in my case), how about to use a big relais to activate it only when SoC is low? I know what in case of a grid failure it could be a race condition but are there any problems on the Victron ESS/inverters side to have not always AC inputs active?

Thanks!

Here we go:

23:26 yesterday

Grid meter shows 68712 kWh

16:17 today

Grid meter shows 68713 kWh

VRM today report: 2.4 kWh to grid, 2.3 kWh from grid

23:58 today

Grid meter shows 68713 kWh

VRM today report: 3.8 kWh to grid, 3.8 kWh from grid

more details about AC input power today

ESS was never in low SoC today. ESS GSP set at -30W which in my case make the ESS system to work energy neutral from/to grid.

Now I have to do the homework about my grid meter

https://www.smartmetereducationnetwork.com/uploads/how-to-tell-if-I-have-a-ami-dte-smart-advanced-meter/Itron%20Centron%20Meter%20Technical%20Guide1482163-201106090057150.pdf

I have a Centron C1SR, interesting enough:

if the above option is enabled, it could be an explanation of everything.... funny enough I did not signed any net metering agreement with my power grid company....

LMAO

Ok, few gotcha.

1) Do not rely on VRM to fine tune your ESS GSP, what you pay is based on the grid meter numbers. The grid meter is the king.

2) My grid meter was indeed counting up when energy was flowing from the home to the grid.

Please verify this in your case. Also I did not get any tamper error messages....

3) I started with a GSP of -30W (energy balance in VRM) and ended up with a GSP of +20W.

With GSP +20W my grid meter counted up 1Wh in 25min unfortunately in the direction home to grid (about 2.4W from home to grid). Since I am pretty close to stop the counting in the grid meter, I left it like this. It could be very possible that the next count is from the grid to the home.....

4) To minimize the electric bill, set your GSP so that the grid meter will count as slow as possible, the energy flow direction is less important at those energy flow rates...

I mean you should not impact the SoC of the batteries with <10W load.

5) Make sure to check your grid meter a couple of times during the day, and check the kWh reading every day when ESS is above SoC, just to make sure is counting as slow as possible.

6) A grid relais to disconnect the grid then SoC > min ESS SoC, does not make sense for me.

The business case is clearly pointing for fine tuning properly the ESS GSP.

PS: https://community.victronenergy.com/questions/259759/pulse-meter-in-vrmcerbo-counting-the-grid-meter-wh.html

After the power company installed the new smart meter that reports the consumption every hours, I did some analysis and in my case I set the ESS GSP back to 0. That way the meter barely moves.