Why Battery cost $50K? More like $10K + patent fees at most.

You can see how batteries are made on some videos and most expensive part will be technology behind assembly. The high cost of Tesla cars is caused now because it is a new, unique product that needs huge amounts of live cash to fund the development etc. Its like with Apple where their phones could be priced 50% of what it is now, but there is a lot of money spent on marketing, future development and to build up cash reserves in case of market turmoil.

It's a similar story to solar panels, except that it might work for a variety of people who live in northern climates or don't have a ton of roof space.

It also might be a good candidate for utilities, most of whom buy electricity at market rates, to forward deeply stored energy closer to the delivery point.

From jegutman elsewhere in the thread, batteries cost $12000, so even buying two would cut that to 6 years and I bet the batteries usefulness would last longer than that so it would definitely add value to a home and probably be a reasonable investment.