I’m new here. I have a system with 3 × MultiPlus-II 5000VA units and 32 kWh of battery capacity. I bought the setup from Helion Energie.
My system has been running well since 4 October. Before that, I had problems with a faulty Cerbo and then a faulty data cable. Both issues have now been resolved.
I have a dynamic energy contract with quarter-hourly prices, and DESS is set to trade.
What I’ve noticed is that DESS’s decisions sometimes make absolutely no sense. Energy prices are very low today and tomorrow because of the storm. At the moment, it isn’t scheduling any charging because there isn’t a sale opportunity in sight yet. As a result, it keeps the target SOC around 30%, which means that the little bit of solar energy we generated today is being fed back into the grid at absurdly low prices, when it would be better to hold on to it until prices are high.
I feel I’m missing some precise control over my buying and selling strategy, such as being able to set minimum sale prices and maximum purchase prices, for example.
What I’ve found myself using Node-RED is that the target SOCs can be configured, but I also understand that DESS can simply override them again when it loads a new schedule.
Is there any way I can get the level of control over the battery that I’m looking for?
In principle, getting control is doable (just keep overriding the target SOCs), but the question is what software will manage it. You’d basically have to write your own DESS that always works and does a better job than the current DESS. So, reading the prices and making forecasts based on solar and wind. There’s already something like that in HA, but DESS still works for me (for now).
It would also be interesting to know what battery price per kWh you’ve set (that explained a few things for me), and perhaps you could share the bottom VRM graph for our interest and amusement?
But I think I’ve got it working now with a Node-RED flow where I’ve set four price thresholds:
Price below which it must charge at all costs
Price below which energy must not be exported
Price above which energy must not be bought
Price above which it must charge at all costs
This is currently checked and set for 16 quarter-hour intervals. It sets both the targetSOC and the strategy.
There isn’t much to see in yesterday’s graph because I intervened in DESS fairly quickly: I disabled the option to export energy and added a very high consumption level after the cheap period, which meant it charged anyway.