Re: I've been pointing this out for years.
'And, no, I'm not buying a battery pack for the house, the energy used in their manufacture, the relatively short life span (10 years, I believe) and the difficulty of recycling them means that for the time being, they definitely fall into the "not green" box. Very useful for people who live off grid though.'
In the next decade, home battery packs will most likely be ex-car battery packs. A 60kWh battery that has dropped to 40kWh sucks in the car, but it's still a lot of power. The projections now are that many packs will spend 10 years in a car and another 10 years in a stationary application before being recycled. The Cobalt used in the Li batteries is what makes them valuable.
Visit Sunamp.co.uk. They are making thermal batteries to store excess electrical energy from PV panels as heat for hot water and home heating. I don't know what they cost and seeing a video on them gave me an idea to build my own. I am guestimating that it will be around £300-£400 for 7kWh of thermal storage if I can get the parts I want to use from a salvage yard. I'm still playing with the design.