Can anyone help me understand the DESS logic here?
It has spent a good few hours of the morning exporting at 15p/kwh and drained the battery to 33% My lower limit is 20% so that’s ok. Now it is importing at 26p/kwh to run the loads and the battery is idle. Shouldn’t the battery be running the loads now?
I think it is telling you - “I have reached the state of charge required now to achieve the future minimum SOC that you have set. I cannot go below this state of charge so I will need to import from the Grid”.
If you reduce your “future” minimum SOC I am sure it will stop importing until the Target SOC is hit again. You may have to wait a while for the system to acknowledge the change.
Access the future minimum SOC through the link at the top right of the dashboard.
Hi Tony, yes I have the large v3.42 which is latest stable.
I think what we have confirmed here is that the logic DESS is using is based on its target for that hour time slot. Its aiming for 72% and will pull from the grid to not go below it which is far from optimal.
My minimum SOC is set at 20% (same as yours), so I want it to not pull from the grid unless it drops to 20% during the more expensive times of day. As it happened the battery only went on to drop to 42% so it could have handled this load.
It seems to work as expected most of the time. Looking back through the stats for yesterday during the peak pricing time it used the grid for 8.5% of the consumption load which in theory could have been supplied from the battery.
Agreed, it is looking at what level of charge it needs at that moment in time to achieve the future SOC. But it is all based on assumptions for future load and PV generation.
I have to switch DESS off on occasion, today is a good example, because it gets my forecast way off. Last Friday Octopus had very low electricity prices for a big chunk of the day so we had the immersion on and electric heaters taking our consumption up from a normal 14 kWh to 33 kWh.
Today DESS has assumed our load will be 30 kWh and wanted to charge my battery up to max. So I switched to manual ESS overnight and will wait until my actual battery charge level coincides with the blue line.
The solar forecast is also a long way adrift.
It is all early days for us so I will patiently wait for the system to get some idea of what “normal” looks like.
Normally DESS will have charged up earlier to coast over the peak prices. Had you had DESS switched on overnight?
DESS will also take power from the Grid to supplement PV if the Grid price of electricity is close to the price you paid to charge the battery. This is to avoid unnecessary degradation of the battery.
I was reminded of this as mine is doing it right now @ 13:00.
Yes I think you have seen similar issues, when the estimates of consumption or solar are off it can cause grid usage. My system has just started pulling from Grid as the clouds have come over and where it forcasted solar there is now none… even though the battery has plenty at 53%
I think the EV and heat pump loads are throwing it off somewhat.
These 2 other posts seem similar:
Cheers for the pointers, at least I know its working as well as can be expected for the time being.
I am quietly confident that it will get to know us over time. Today was not such a good one, but I understand why it got consumption a long way off but don’t know about the solar forecast.
Good Morning @teejay . My observation is somehow similar. Super sunny day, DESS decides to charge battery from grid although todays PV yield will be far enough to get the battery charged including todays consumption and surplus energy for feed-in.
Solar forecast seems to be quiet inaccurate sometimes. The local forecast from wetteronline.de (for example) is far more precise on some days in my case.
I agree, we are somehow in a state DESS version 1.0 and I think we all need some patience until DESS gets improved step by step. I’m confident, that will happen. And I’m convinced, DESS is the right idea how to steer an ESS.
@teejay . Although your answer was a little bit of topic, your thoughts about DESS have been excellent and I was already thinking about starting an own post addressing exactly that part of the story of DESS: How to enrich the DESS algorithm with information only I can know in advance (absence, unusual consumption, …) We should start such a post together and combine our thoughts and feedback
