Battery charge algorithm when charge level set below SOC value

Apologies, if this has been covered elsewhere and I missed it.
I have been thinking about the best Octopus tariff for the forthcoming main generation season and whether I should move away from the current Go Faster 4hr [21:30-01:30 (5p/kWh & 24.25p/kWh)] or not, assuming that many of you may also be considering this.
My question relates to portal/app setting that would enable use of the Go Faster price plunge to support house load without the need to charge battery. Earlier this month I have been manually limiting the SOC% charge ahead of sunny days. However, when I set the charge level below the battery SOC% at the time of window opening, the battery starts discharging first before the grid takes over (Mode 1 - Dynamic; Smart Charge). This clearly is not efficient use of the battery charge, and was hoping that the algorithm could be modified and grid takes over of the house baseload regardless the battery SOC (e.g., battery being 40% SOC and charge level set for 7%). Or am I looking at it too simplistically @simon_swinburne?

The reason why I'm interested is that last year (my first season with the system), I was on Flexible Octopus for import and Agile Outgoing Octopus for export (exporting at average 19p/kWh) and was therefore thinking of switching to something similar from March, as we are getting more sun. Having spoken to Octopus, I understand that they have not published their capped rates yet, however, I was told that I can stay on my current Go Faster tariff for 12 months from getting on it (in my case till early Nov 2022). Whilst I do not plan to be charging the battery daily from the grid over the summer, and the system was running at 85% self sufficiency for the period April-October, there clearly were days when the battery run out early and AC charge would have been helpful. My thinking is that staying on this tariff would provide protection against the forthcoming April peak rate increases, enable me to charge the battery from the grid on cheap when weather is poor and/or run appliances during the price plunge window, whilst the overall cost being cheaper despite some loss of earnings from export with rate dropping to SEG only. Thoughts?

You can set Battery Discharge rate to 0% I guess on the new portal (inverter card > settings > battery > discharge rate)
Although suspect you'd need this automating via the API (or GE need to add it as an option to the charge timer sections) to save you having to do this manually in you cheap window.

I think stick on the current tariff, whilst you can, for cheaper charging when you need it and appliances usage too.

Will you be able to generate enough solar to cover morning electric use? (Especially if you use an electric shower).

I guess what you really need to do is get a spreadsheet or calculator and try to work out how much you could gain with a better export tariff and see if you’d end up making enough to cover the higher import costs.

Personally the goal for me is the lowest rate per kw possible. As in an average low rate. So far I have managed to keep this below 8p per kwh over Winter. So with Go Faster at 5.5p until October and the new export offering 4.1p I will stick on what I have. For me I think I will balance out around 0p per kw once my EV arrives for 6 months of the year and hopefully stay under 8p per kw though that depends what happens to the Go tariffs over the next 12 months.