Mate of mine owns an "energy saving" business. Does solar panels, heat pumps et al AND he sells batteries. I had a chat, over a beer and he advised me to wait as my energy isn't expensive. My 89 euro a month is 80% gas and 20% electricity. A quality 15kwh battery over here costs between 6 and 10 grand. I pay around 200 euro a year for electricity since we installed the solar panels. I don't perceive a time when a battery would be cost efficient allied to a good ROI as the only way to do that would be to go all electric, which isn't possible as we're not allowed to use electricity for water heating unless you go down the route of installing a heat pump including drilling down about 25 metres... total cost 30K. You can then come off gas but you'll use a lot more electricity. You'll break even maybe 20 years down the road. Our government had made going down the water pump path as of January this year. Just over a year ago, they realised the take up was low so there wasn't the capacity to complete on time plus most of those without a water pump couldn't in many cases afford it. Others, like me, decided the break even period was way too long making the investment unwise. This summer we're having a new gas powered central heating boiler put in for 3 grand. That should last 20 years and see us not having an expensive water pump.
Chances of going down the battery route are also very low at the moment. What I would consider would be a move to hydrogen if it ever became feasible and affordable.