@allyfish I think that Cosy ought to work well for me as I have the ability to store 27 kW/h and this could be ‘filled up’ in either (or both!) cheapest 3 hour slots each day. I could also arrange for the DHW to charge once a day during one of these slots, or even part charge twice a day whilst also setting the ASHP to boost (perhaps by 1 degree C?) during both cheapest slots which should result in reduce demand for heating during the peak time. The Tesla app allows me to be ‘off grid’ in effect during all high cost periods of the tariff thus ensuring I do not consume at the maximum (and probably the medium rate too) rates of the tariff. Haven’t heard back from Octopus about swapping to Cosy yet - but I’ll be ready to re-set the devices when I do! Regards, Toodles.

Octopus' latest version of Cosy tariff now includes a third low rate tariff period from 10pm-12am. Added to the two 3hr periods 4am-7am and 1pm-4pm, that's 8hrs a day of low rate tariff.

So, having seen that Agile was not really saving me anything, due to limited 13kW battery storage and no mid-afternoon lower prices for quite some time, I've flipped from Agile back to Cosy. I think over the winter months I'll make a modest saving with Cosy if I get the charge times right and shift 85% or more of my energy import to lowest rate.

The attractive points were, first, the 3rd late night low rate period, which allows a third extra battery charge in the event we run the ASHP overnight, which we only do in very coldest weather periods, normally it is off from 9pm-4am. Second, the low rate periods being fixed, as I've got a little tired of constantly checking Agile tariff for the next day, and manually tweaking and adjusting the scheduled charging times on the oh-so-clunky Growatt Solar PV app. I'm more than happy to set and forget and let it all do it's thing.

I have also had a bit of a pantomime with Agile where there were a couple of 30 minute slots missing from Octopus' smart meter records. That resulted in late billing and them trying to bill the entire month in which the missing data occurred at flexible tariff rate. That's in their T&Cs, but as 85% of my load was imported at lower rates, it was a hugely punitive. After some wrangling, Octopus Customer Service applied what they said was a 'discretionary credit' to my account, but what I assert was an unfair and wholly disproportionate billing estimate for the missing data.

Maybe I'll flip back to agile over the summer, to take advantage of the lower daily standing charge. During the summer I'm largely self-sufficient with a modest 3.6kW solar array, and my only outgoing is standing charge. I don't need to import much at all. Good that you can just flip smart tariffs on a whim with Octopus, and it's instant. Fair play to them.

@allyfish I changed to Cosy from Agile on July 1st. and for very similar reason; the faff factor does have a value! I’ve been monitoring the ‘average off-peak’ rate for Agile and nearly all days have actually been higher than the known, fixed amount charged during those 8 ‘cosy’ hours on the Cosy tariff. I’m staying with Cosy at present - even though it rose 10% on Oct. 1st. Regards, Toodles.