[jnw2]

Several strings of solar panels + lithium ion batteries might very well be cheaper than paying your local electric monopoly for transmission line capacity in 20 years. And if the non-redundant parts (the inverter, perhaps) fail, it might not be all that different from your water heater failing today.

(Although if we had that technology in cheap enough form, some of the major loads in your house may switch to DC to avoid conversion losses to AC, since solar panels and batteries are both inherently DC technologies, and that might make the inverter less important.)

[dalke]

There will still be a grid. The scenario you mention will be useful for some, but assuming $80/month for electricity over a paid-for grid vs. $10,000 for installation of cheap solar panels+batteries gives a pay-off time of about 10 years. (Currently solar water heaters cost about $5,000, so the best is 5 years.)

I don't think most will be willing to take that capital investment.

It would be interesting to see how distributed solar compares to grid-based distribution in the face of large disasters like a hurricane or ice storm. Especially if the power lines were underground. I assume that those with damaged panels would quickly look for replacements, causing an instant demand and price spike. While the large electricity companies would have stockpiled reserves and have agreements already in place to handle the short-term demand. I don't know how this would affect the overall long-term costs.

[jnw2]

IIRC, solar prices have been dropping at a rate of 7% per year. If that keeps up, and if the grid price remains constant, solar will eventually become cheaper than grid.

In 1992, would you have told me today's smartphones would be impossible?

If you only lose a few solar panels in a storm, and most of the panels on your roof survive, you may just use a bit less electricity for a while.

[jrabone]

I don't think you necessarily need Li-ion for that - in my experience lead acid works well enough in the domestic case, is a lot cheaper and probably safer (although hydrogen venting is perhaps an issue).

I built a little mixed DC (lighting) + AC (1kW inverter) system out in the garden (far enough from the flat that running a cable would be a nightmare of planning permissions & digging trenches).

Since it's for intermittent use the panel is tiny (50W Kyocera) compared to the battery (110 Ah 'leisure') & inverter (1kW true sine), and it works just fine even here at 53 deg latitude. It would scale up for the entire house quite well, were it not for the fact that it's a four-in-a-block with a communal roof, and 1/2 loft space unusable due to loft conversion.

[jnw2]

There are some interesting questions about economies of scale, etc, though.

If we figure an average American has a lead acid car battery and maybe a laptop battery pack, we currently have more lead acid batteries than lithium ion, certainly by weight, but probably also by total watt hours.

Tesla and Nissan might end up inverting that ratio in a market where they merely have to get the battery to beat the cost of gas; and if we get to the point where every American has an 85 kwH battery pack in their car, that's multiple days of average US electrical consumption (I believe average per capita electrical consumption is about 1.5 kw, and average per capita total energy consumption around 6 kw in the US).

Meanwhile, there's no path to pushing up volumes of lead acid battery production significantly. Maybe there will be a few old lead acid car batteries getting recycled after Tesla conquers the world, but if that's all we're relying on, those recycled batteries won't power very much in the grand scheme of things.

[stcredzero]

Nickel-Iron batteries have a life measured in decades and are very robust against deep discharge. They can also be refurbished. Their formulation has been around since Edison. In fact, I think he invented them. Their big disadvantage: they're heavy. Perfect for home use.

EDIT: Edison did not invent NiFe batteries, but he developed and championed them.