Predbat to decide which Octopus tariff is likely to be most profitable for the next day and expose that info for other addons to use?

[samtate]

I just added a PR to the Octopus MinMax bot. The Octopus MinMax bot currently decides at the end of the day whether Agile or Go was cheaper for you that day based on your usage and then switches you to the correct tariff which applies retrospectively to all of your usage for that day. This is great for people without batteries but those of us with batteries will want to know from 00:00 which tariff is likely to be best for the day ahead so we can switch our tariff to it and then have predbat take advantage of cheap slots to charge, whether that's 00:30-05:30 on Go, or 03:00-08:00 on agile for that day etc.

My PR adds a predictive mode to the bot which very crudely works out if Agile has sufficiently long slots that are equal to or below Go's overnight rate, and switches you based on this. Then of course predbat connected to the Octopus API can see the tariff change and recalculate the plan.
This is great for people whose battery is larger than their daily usage but it doesnt take into account actual usage, so if you use all your battery by midday, then you might end up the rest of the day using Go's day rate when Agile may have been better.

Predbat already knows our predicted load, predicted solar etc, so is in a position to work out which tariff is likely to be best for each day. I wonder if its possible for predbat to do this calculation for the current day and the next day and expose them to home assistant as entities that can be read by other addons. It wouldn't be in scope for predbat to actually switch you but it could expose the best predicted tariff and then a minmax addon for home assistant could read this entity and perform the switch accordingly.

I look forward to hearing your feedback, cheers!

[gcoan]

I think you have the predbat side of this already in place with predbat compare https://springfall2008.github.io/batpred/compare/

creates entities like this:

[samtate]

Hi @gcoan yes I did notice this not long after I posted the discussion hence why I closed it! Cheers for pointing it out, it's a fantastic tool! I've now got my bot more or less automatically switching between tariffs just after midnight, the issue I'm having now is that obviously predbat isn't aware I'm going to switch until I do the switch.

So currently today I'm on Agile as the rates were lower today but tomorrow I'll be on Go again. Obviously predbat thinks I'm staying on agile indefinitely even though the Compare result said Go is better, so its holding my battery charge using the 15-17p rates. Whereas if it knew I'd have 8.5p rates from 00:30 tomorrow it would export any remaining battery SoC before 00:30 and then fully charge back up at 00:30:

Obviously at 00:01 when the switch happens, predbat will recalculate and charge up from 00:30 at 8.5p but the export arbitrage will be lost. I can see there is an option to manually override the next day's import rates using the manual API but is there an option to just say "I'm using Agile from 00:00"?

Fully appreciate this is a very niche use case and I can try integrating the manual API into my script.

Cheers!

[gcoan]

I can see there is an option to manually override the next day's import rates using the manual API but is there an option to just say "I'm using Agile from 00:00"?

No there isn't anything like that. The nearest is you can define the rates using the octopus URL rather than the bottlecap dave integration, so you could edit apps.yaml to the new rate URL, but that would take effect immediately rather than at 00:00.
As you say, quite a niche use case.

Personally I know Octopus currently allow it, but it doesn't seem right to swap rates on an almost daily basis, you have to take the rough with the smooth with agile, and we certainly had some rough last winter which is why I moved to Cosy in the end after 15 months on Agile.
Most of the time there isn't much in it for me between Agile and Cosy, just when its very cold and no wind Agile is significantly more expensive, and of course I loose out on the occasional cheap days when its windy. But Cosy is certainly easier to deal with.
Out of interest how much do you estimate you save by swapping tariff?