Octopus specifically market the Flux tariff as enabling arbitrage between the cheap rate at night and the higher rate 1600 to 1900 slot.
EDIT: for more detail.
https://octopus.energy/smart/flux/
[quote Super cheap rates between 02:00 - 05:00 every day, when you can top up your battery with any extra energy you may need.
A peak rate between 16:00 - 19:00, the optimum time to discharge your battery and export surplus energy back to the grid.[/quote]
I'm still practising with my system, but yesterday I exported down to about 40% at 1900, then the battery dropped to 12% at 0200 and I charged up to 30% at 17.76p/. Then it dropped as low as 22% before recharging from the PV array to 100% by 1445, then exported about 4.5kW I couldn't store at the usual export rate of 18.61p/kWh. Forced discharge between 1605 to 1855 back down to 45% at 30.45p/kWh, including the PV array output, about 11.5kWh exported. I'll put the oven on later, cook fish and chips, watch some TV, and then recharge to 70% overnight because rain is due tomorrow.
July production was down 20% from expected and because of the export rate I made £50 net considering gas and leccie standing charges and gas use. And this was without the overnight charging shenanigans regarding arbitrage
Flux is a tariff that will subsidise solar PV and battery installs for as long as it exists. And it's not even gaming the system, it's profit sharing.