All the information and advice I've been reading is that since the government stopped with their feed in payments just having solar takes a long time to pay back. What sort of timeframe are you working on for your payback? I've started to get prices of between £7-£10k with the majority of fluctuations being on how much battery storage I want and for us, as we are lucky enough to have an EV makes our payback time under 7 years with our usage and shifting when we use appliances etc. The idea of storage is that throughout the day you will be storing the excess energy which will then be used during the evening in peak times when you will be using energy however your panels will not be generating. £0.055 is a decent price for export but is still more than the amount you will be paying in the early mornings and evenings when the power generated is less. I've also been looking into actually mining and using the energy this way even before exporting as on my Go tarriff I'd only get £0.03. Just to note that Agile at the moment is mega money, not dropping much less than £0.35 per kWh so not sure what price per kw your figures have been worked out on...even if you look at a smallish battery I think it would be beneficial. Out of interest what kw system have you gone for?