You can make that tariff work without a battery, just that you need to be flexible when it comes to load shifting to maximise the savings. Moving consumption out of evening peaks would be enough over a course of a year.

The spikes in the last 2 years have happened for very short amounts of time. If renewables are working, you don't get a spike, and save loads on this tariff. The small amount of time they're not, you sometimes have to pay more, but not for long enough to matter. It's fundamentally more effective for everyone than the default of buying the insurance of fixed prices.

Over the last year of being on the Agile tariff, my average weighted price per kWh is £0.12 with a total saving of £506 over the year (drive an EV with an average of 4500kWh usage over the year).

I'm happy to shoulder a very 40p peaks every so often as it's very often cheaper overall.