Lobster wrote:
This gadget made the main headline of The Times today - here's a non-
paywalled-version from the Mail:

http://tinyurl.com/l3hlslv (or
http://www.dailymail.co.uk/sciencete...la-set-reveal-
home-battery-Elon-Musk-unveil-power-pack-tonight-slash-electricity-
bills.html)

Quite surprised never to have heard of this before, especially (AFAICS) in
this ng.

Thoughts? Shall I go and buy a PowerWall then?!

NO

Once you factor in the replacement cost of batteries over time this is
not a viable scheme.

The $3000 pack will store 7kWh or about £1 of power which will reduce
every charge discharge cycle to the end of life
Typical life of a battery pack might be 2000-3000 cycles but only if
taken to 50% of capacity approx so that is 50p of power.
£1000-£1500 of power in a battery costing £2000.
That is ignoring the capital cost of rest of the system.

There are better ways of storing/using excess solar power by heating
water especially if you are already using electric water heating.

Look up Immersun and similar products. DIY versions available too.
look at http://www.mk2pvrouter.co.uk/