Why does DESS not take advantage of low, zero or negative rates from Octopus Agile to fully charge the battery? I’ve got a 2.5 hour window tomorrow morning where rates are effectively zero, the battery (15.5kWh) is at 28%, forecast 18% when the cheap rates kick in, and it’s only going to pull down 1.36kW in a single half hour slot.
I’ve got no solar which might mean DESS is not perfect for me but free is free, right, why not fully charge the battery?
Update. It actually imported a bit more than the forecast, 2.05kWh between 3 and 4 and 1.83 between 4 and 5. The battery topped out at 49%.
I know the grid can do more because if I raise the minimum SOC above the current level it charges at over 5kW.
The only reason I can think of not to make maximum use of free electricity is if the system knows it will be negative rates in the next couple of days. The Octopus tariffs are not published yet but I suppose it could make that assumption based on the weather forecast. I’ll have to wait and see.
Prynhawn da! In my experience (Green Mode), it only tries to charge enough to see you through the next bit.
After months of manually setting ESS schedules, DESS doesn’t do it like I would have - it does feel like the battery doesn’t quite have enough in. But it does seem to have learned a bit over the last couple of weeks, to the point where I almost trust it to do the best thing (I have the hack installed also). I haven’t tried Trading Mode, you would think that it would take more advantage of the -ve pricing.
Diolch yn fawr Seimon, tomorrow’s Octopus rates don’t give any justification for passing on last night’s rates. I might try trading mode but I don’t sell, needs a bit more investigation.
To be fair, the “off the shelf” solution is far surpassing my expectations, when I started the project I’d factored in days programming the schedule so when DESS, that I’d never heard of, launched in September my mind was blown. It’s still in it’s infancy and of course Octopus isn’t the only supplier it’s interfacing with. I intended my post to help and inform the dev team and I hope it was taken that way.
Like with any new tech, we soon take it for granted and want more. I’m sure it will continue to improve over time and thanks to Victron, above and beyond expectations.
Lle wyt ti Seimon?
Yr Wyddgrug!
Agreed, I would also prefer it to keep the battery a bit more topped up than it seems to. But I guess the green mode priority is PV consumption, so it probably wants to leave enough space just incase it turns out sunny? Dunno, I’m just guessing also; I was also sad that it didn’t consume maximum -ve units 
Some more feedback on how DESS is working with Octopus Agile.
I can’t think of any logical reason why it’s powering the AC load from the grid at 6pm when the rate is 45p per kW and sustaining the battery at 27%.
It’s a 15.5 kWh battery and minimum SOC is set to 10% so it could easily wait a few hours until the price is 15p.
The Energy chart at the bottom has a highlighted section timed 17:00 to 17:59 but the time now on your phone is 19:19.
It also begs the question as to why it was going to take power from the Grid during that period.
The section marked “Now” on the Energy chart shows energy coming from the battery, not from the Grid. I know that it doesn’t answer your question, as the chart at the top clearly shows import.
Just a couple of observations to add to the pot.
The time Now = 18:00 to 19:00 but the time on your phone is 19:19. Is there a mismatch in the time settings on your Victron?
Thanks Tony, I’m currently in Spain but good observation. Cheers.
Doing it again, 50p per kW, 28% in the battery. 