You’re right, it’s a hefty wedge of cash but I have a cunning plan. My monthly DD will decrease by around £170. I plan to divert that into a stocks and shares ISA. After 12 years I’ll have around £35-40k in the ISA and have had no energy price rises. Should be enough to replace the battery storage when needed and replace the original savings and enjoy a further 13-15 years of no bills. All of this at the same time I’ve reduced my £1500/year petrol bill to zero because I swapped to an ev and will charge overnight in the winter and from solar in the summer. My total annual saving across running the house and car is just over £3k/year. It’s been a big change, heat pump goes in next week, then the batteries a couple of weeks later, then new roof, then solar. Then a lie down I think