Using FW v3.60~49, DESS decided to let solar energy go to grid instead of charging my battery. It had planned to start charging later, but my battery is 16kWh and it can easily take all available solar. And I will consume it during the night. This behaviour causes me to sell cheap during the day and eventually buy from grid during the night with a higher price.
Any thoughts? DESS is set to trade mode. Battery was sitting at 5% (low soc limit) during the time of writing. My expectation is that if there is excess solar, and the selling price is lower than any expected buy price, the excess solar would go straight to the battery.
I disabled DESS and it started charging as expected.
If you want to optimize for self-consumption, you should be running in Green-Mode.
In your example, trade-mode is right:
It sold energy for ~ 18,19 cents
It can therefore charge again immediately
At night, it can purchase energy for ~14 cents.
If DESS would have kept that energy in the battery for self-consumption, it would have caused opportunity costs of 18,19 cents / kWh rather than buying back for 14 cents, when needed.
Edit: Ah, you are refering to the hours AFTER bat2grid, where solar was feedin?
Well, the first hour there makes sence. Feeding in for 14 cents and buying back for 14cents is STILL better than loosing 20% energy with a battery round trip.
But the hours after that - I have to see the schedule to figure that out - could you give me your side-id? The numeric one in the VRM url?
Hi, yeah, I am talking about those hours after bat2grid, when the solar started working and energy was exported with low price. The export happened with lower selling price than any possible buying cost. Therefore it should have gone to the battery to wait for future self consumption or selling opportunity.
I fully agree with all DESS decisions before and during the morning bat2grid.
VRM calculated, that it needs a maximum soc of 54% at ~16-17
Therefore, it calculated that charging the battery in the hours of lowest feedin starting at 12 would have been sufficient and the earlier hours up to 12 can be used for feedin.
Mind trademode is not caring all to much about self-consumption. It won’t charge the battery to 100% if it can’t see a sell-opportunity in the not to distant future, but using the maximum available grid prices to feed in otherwise.
So, you should eventually switch to Green Mode. It will give battery 100% Soc priority and THEN start to look at an eventual optimization resulting from purchase / selling to grid.
Alright, thank you for checking. I previously thought Trade mode would find an overall monetary optimum for the system, which was my reason for choosing it.
I will switch to green mode. I didn’t know it could sell as well. Nice. Thank you!
Edit: Another unwanted behaviour datapoint from Trade mode is happening tomorrow after midday, it makes no monetary sense to let solar slip to grid, when it could be used to cover expensive buy energy later. Let’s see how Green mode works.
