You're absolutely right, you need to keep it under review. I locked into the 12 month fixed price of Go in mid-December 2021 at 5p and 24.6p but by end of January 2022 there had been I think two increases in the peak rate first to 30p and then something like 36p and the off-peak Go from 5p to 7.5p. Those steep rises prompted me to reassess the Solar PV and Storage economics which when I'd looked at them last in July 2021 Solar PV was still more expensive than Octopus's 24.6p Peak-rate. I'd calculated that as I'd only be in this home a maximum of 10 years I'd have to write off the £10k investment over ton years ie £1,000 per year and the predicted output of 2,800 kWh in year One. This means that in year One the cost of Solar PV generation would be 35.7p per kWh in the first year and rising thereafter (because PV output degrades 3% after 1 year and then 0.5% per year for years 2 to 10).
However, in early 2022 I started seriously researching Solar PV and Storage and have on order 4.8 kW of PV and 7.8 kWh of LEP Battery Storage with a Hybrid Inverter capable of 3.6 kWh constant and a boost up to 5 kW for up to 10 minutes. This should provide for most of my daytime use for 8 months of the year and then I can supplement the Solar by charging the Batteries on Go off-peak in the winter months thereby minimising but not completely eliminating Peak-time usage. I will monitor the situation closely and it may be that switching to Go-Faster with a longer off-peak period which starts in late evening would be more viable if the batteries are exhausted too early in the evening but in the evening my house is only consuming 300 to 350 watts because the heavy loads of Dishwasher, Washing Machine and EV Charging are already done in the early hours on Go. Who knows, Agile might return to be a more viable option.