I think it's well worth a bit of a ponder here at what you're actually trying to achieve, @ellyse. I know you say you've no control over what's been installed but that's only a problem if you've identified something you actually want to control. My Ecodan, for instance, has been set up well enough that we can just leave it alone, and the only control I actually need to do is tell it to go into holiday mode at certain ad-hoc times (for which the Melcloud App is perfectly sufficient).

You've also said you'd like to add some battery storage to the solar array you've had installed and I can understand why that might be appealing. If you were to do so, I can also see why control would be rather more important (we couldn't practically do without the control we now have over ours), but the points everyone else has raised since are important ones that can only be put into context alongside an understanding of how you'd be likely to use the extra gubbins.

@jamespa in particular has mentioned on one or two other threads that he cannot quite make a cost justification for a battery to add to his setup. This is partly echoed by @transparent and @judith - it's not to say the cost can't be justified but the devil's in the detail. I was able to justify it, so I think there's value in identifying a few of the key variables in your decision-making.

1. The value of your solar panels is two-fold; you're running your electricals for free up to the amount your panels can produce at that point and you can be paid for any excess you don't use and that gets exported to the grid. How much those two figures amount to is entirely dependent on your choice of import and export tariffs, but historically people have been on standard variable tariffs (25-30p/kWh import price) and a pittance export (2-4p ish) although both of these are pretty inaccurate guides now. As a result, as of only a couple of years ago it would have been VERY advantageous to be able to store your excess instead of export it.
2. The range of tariffs has quickly expanded over the last few years and time of use tariffs are much better understood. The real value of a battery is that it can effectively time-shift your usage and, in our case, that means we can avail ourselves of the cheap bits of the Octopus Agile Import tariff whilst ensuring a full battery to avoid importing during the expensive 4pm-7pm stretch. That alone brings our average import price per kWh down to the low to mid teens.
3. It's also true that if you have a battery big enough to cover your needs and have some capacity left over then you can take advantage of an agile export tariff's high points to export at the best prices which can sometimes rival standard import prices. Once again, it's about filling up the battery cheap or for free and then timeshifting when you sell.
4. A battery has a finite life and I've found the cost per deplete/fill up cycle that you need to budget for is probably about 4-6p per kWh stored and then taken out again. In practice the battery will probably last loads longer after you've depreciated its cost on paper but you still want to play safe I think. The important point here is that your battery's value to you has to take into account that if storing a kWh you produced looks like a saving of 10p compared with the import price, the real saving is closer to 5p.
5. The real fly in the ointment for justifying a battery at the moment is the Octopus Outgoing fixed tariff where every exported kWh is 15p whatever time it's exported. 15p is a pretty big chunk compared with import prices so it dramatically reduces the value of storing instead of exporting what you produce. The battery is still useful for keeping you away from the expensive import times but the savings are less. However, as has been mentioned in other threads, that tariff is currently losing Octopus money and so cannot be expected to continue indefinitely.
6. If you have or shortly expect to get an EV, that also changes things a lot since minimising the cost to drive around dwarfs any attempts to minimise your home's leccy bill. A home battery can certainly give you a fighting chance of having your cake and eating it but you don't want your home battery and your car fighting to get the cheap leccy at any time they can't both get all they are asking for.

@transparent is right when he says that the key in all this is to try to predict how things will look in 5 years' time or so and plan for that. My guess is that the only right answer is to do a few sums, look at your likely usage patterns and then take a big deep breath and guess.

@majordennisbloodnok Not forgetting to wet your finger and hold it up in the wind!😏

I’m dipping my toe into Intelligent Octopus Flux at present and just had my bill for the first week. I note that towards the end of the three hour export period in the afternoon, my battery runs down and stops at 20% and Kraken then recharges the battery for a few minutes at the higher tariff before it resets itself and just supplies my residual domestic drain until 19:00 when the standard rate returns. I will be reviewing progress as we go into summer and am hoping that solar export at this higher tariff will prove advantageous and at the same time, assist the grid - only time will tell. Ist, weeks performance as a screen shot attached. Regards, Toodles.

So sorry to follow up self but this may clarify things as this is actually from the itemised bill rather than just a quick summary.

 Regards, Toodles.