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Running off-grid solar cell systems has been quite popular in the hobbyist space for a while. There are tons of products and examples out there for DIY installations. These generally use lead-acid batteries and inverters to convert DC up to 110 VAC for your house.

There are already DC power standards used for electronics, too. Telecom equipment commonly uses -48 VDC. However, I expect that you will find that the majority of your electricity is used by motors and other appliances that run directly off of 110 VAC.

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Exactly. And not even just in hobbyist space. There is a long-established history of running homes off of solar power using lead-acid batteries in professional installations. And not even just in homes; many, many businesses have invested in it. The only barrier is financing... and companies are even forming California to amortize the financing of solar to the home, so home owners can get started with ~$200/month instead of a $20k installation.

There, the possibility that a "Tesla" battery could do anything the same or better is not new, redundant and this article is just marketing hype: It's a report of an investor call, for crying out loud, not researched journalism. There is no reason to expect a lithium battery in the home would be cheaper than traditional, established lead-acid batteries.

The advantage of lithium in a car is obvious (weight, if you haven't had your coffee). In the home, weight is not a factor. Lithium would save space, but at the expense of lifetime and cost. Since cost is the only factor holding back installation now, I don't expect many people to pay even more for the privilege of a lithium home battery bank.

BTW, in reference to your expectation, a motors expert I work with says that 50% of all electricity consumed is consumed by motors. The refrigerator's compressor motor is generally the heaviest electricity consumer in the home.

The barrier is batteries and the cost of them. I briefly looked into this. To run my house's essentials: heat, water, fridge, and 1-2 outlets for electronics I currently use a 5KW generator when the power goes out. I have a transfer switch that shows me my peak current: roughly 2.5-3 KW when the well and fridge are running. A deep cycle marine batter that you can readily buy from Amazon costs $100 or so and gives you 12 Volt 35AH. That's 420 Watt hours. Thus to run just the bare essentials in my house for 1 hour, I'd need 7 of these (assuming perfect DC to AC conversion). To run for 24 hours, I'd need 168 of them. So I am investing $16,800 in just batteries. But don't forget, that there will be periods of cloudy days, so you want enough capacity to get through those. I haven't seen the sun here in CT for about a week now... Oh, and in the summer, I do like my AC which itself pulls 5kW and has a relatively high starting current. I'd have to quadruple the capacity to run it. My basement is simply not large enough to contain all these batteries + inverter system. Doing all this to save under $200/month on the electric bill will never pay for itself.

A low cost space saving battery with high energy density would be pretty game changing here.

In a home, size and weight is a bit of a factor.

Is the building strong enough to support the weight? Space also has a cost.

It would also cost more to manufacture, transport and install big and heavy equipment, because it is big and heavy equipment.

As you probably know, lead-acid also requires more maintenance than Li-Ion. Li-Ion's nice selling point for consumers is that you don't need to (especially) worry about stuff like battery memory.

Why do we need to use a chemical battery for large things that aren't mobile? Why can't we store kinetic energy by, say, raising and lowering a big counterweight?

Steel is 36 cents per pound. Assume you can move it up and down 300ft (30 story building). This will get you 1pound * g * 300ft of energy storage. This comes out to 300,000 USD/kWh, about a 1000 times more expensive than Li-ion batteries, per kilowatt-hour.

Gravity is too weak. Flywheels are the way to store kinetic/mechanical energy, but the up front cost is pretty steep.

http://physics.ucsd.edu/do-the-math/2011/11/pump-up-the-stor...

"The main problem with gravitational storage is that it is incredibly weak compared to chemical, compressed air, or flywheel techniques (see the post on home energy storage options). For example, to get the amount of energy stored in a single AA battery, we would have to lift 100 kg (220 lb) 10 m (33 ft) to match it. To match the energy contained in a gallon of gasoline, we would have to lift 13 tons of water (3500 gallons) one kilometer high (3,280 feet)."

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