I notcied something that I do not understand yet. I have a 3-phase setup based on 3 x Multi-RS, an VM-3P75CT as grid energy meter, and a solaredge inverter connected to the AC-out as essential load, and 4kW peak on solar panels connected to the Multi-RS. I am doing some testing to see what happens when disconnecting the grid.
I tested with 2 situations when disconnecting the grid:
Battery full / 100%: The frequency goes up to 53,2Hz, the AC inverter stops producing power, The DC coupled solar panels decrease the power in line with consumption. this looks good to me.
Battery low / 19%: Here also the frequency goes up to 53,2Hz which makes the AC-coupled inverter stop producing power!
I would expect with a low battery that the system would start charging the batteries, and the produced net-frequency of the Multi-RS-es to stay around the 50Hz to keep the AC-coupled panels running. I tested with several modes like:
Dynamic-ESS off/on
Change to ‘keep batteries charged’ mode.
The cerbo runs FW v3.80~14, the 3 Multi-RS runs v1.29, grid code is Europe.
What am I missing here? Why is it moving towards 53,25 Hz ?
The first thing is to test not using beta code. The main forum sections are intended for production versions, so you need to rule out the behaviour that test software can introduce.
I do have to set the system to ‘keep batteries charged’ though to charge the batteries. With dynamic-ess enabled and grid lost it seems to not charge the batteries with excessive power which I would expect in case of grid lost-> keep batteries as full as possible with solar power.
ok, so hopefully resolved in the current code then.
Venus doesn’t control DESS, it merely follows instructions from VRM, so that is unrelated to this topic and best discussed in the DESS section.
Yes, I assume that the net-frequency issue is solve in ~21.
Still weird that the system tries to control charging batteries based on grid-energy-prices when grid is disconnected.
In ‘optimized wih battery-life’ it does not charge the batteries at this moment and grid-disconnected. The control of the PV-inverter now goes through ‘dynamic power limiting’ and not by increasing the net frequency.
I would expect in that case that during grid-lost DESS is implicitly disabled and the system tries to save as much energy as possible in the batteries, thus use the solar power to charge as much as possible. Simply because grid can be down during day and night, and the system then starts the night with empty batteries. I think that DESS has no use in systems without a grid connection…