Home solar probably makes sense (or will soon) because economies of scale don't affect it as much and a lot of the power being produced can be consumed right there.

The one wrinkle being the assumption that "the grid works well." It doesn't always. If the grid is saddled with a bad price structure or poor reliability then the equation changes considerably. I suspect that a solar+batteries combo will be really popular in certain third-world countries where grid power sucks.

another unmentioned cost of especially wind, but also to some extent solar is the huge transmission upgrade needed to support wind. It is a huge cost and it is never accounted for in the numbers when people are pushing for wind and solar (because it usually ruins the claim that wind and solar are cheaper over their lifecycle vs natural gas). They are also costs the consumer largely gets stuffed with via billing items outside of energy cost so it's kind of insidiously hidden from the consumer.

The utility companies should probably be investing in EV charging (like the ability to buy electricity from a shared charger, and bill it directly to your home account instead of appearing on the charger operator's meter), in order to maintain/increase demand for their product as solar takes it away.

I think we will see mostly utility scale storage. Most people will have an electric car that they can plug into, but that will only be done to keep the fridge cold when the utility goes out.

So local storage reduces the amount of both the power taken from and provided to the grid and therefore is beneficial for grid stability.

The problems start, when the storage is not local anymore, that is when the power surplus is not at the same location as the storage itself. A few examples: When the sun is shining your electric car is probably at the parking lot of your workplace and you can't store the output of your PV system. Or when it's a rainy day, you and also all other households in a wide area around you, wont' produce much power. Then the power has to come from somewhere else, e.g. a sunnier place, offshore wind or gas power plants.

So to use all the distributed storage effectively, you have to route the power around a lot, which probably makes changes in the power grid inevitable. How much one has to invest in the grid and how that relates to the overall power price is probably a very complex topic depending on a lot of variables including geography, power mix and cost of storage.

There are also going to be (hopefully) some low cost utility scale storage options that, along with the 50% cost advantage of utility solar over rooftop, could be combined with the existing distribution infrastructure to provide low-cost and low-carbon energy for transportation.

You're also perhaps assuming that this infrastructure exists. Right now, most US home connections to the power grid can't transmit power outside of their own subdivision. You did say if "the grid works well." You could say that includes, "works at all between you and relevant points."

Even if the solar plant doesn’t generate enough in the middle of summer when demand is high, its grid connection means the batteries could be charging from surplus wind at night.

Not that this addresses my time-volume issue, just saying it’s not worth considering from the single home perspective except in unusual cases.

So storage still makes a lot of sense, because if I want to do anything about renewable energy, I unfortunately have to do it myself. Putting some sort of solar system on my house will cost ME money; either outright, leased, or through a home-improvement loan plan. Which is sad, but it is what it is (and kudos to what the government HAS done to bring down these costs). Since it's all on me to reduce my carbon footprint, that energy produced must be stored, and these home battery systems (Tesla or not, there's about 2 other choices though, it seems in my research with companies locally) are not all that expensive considering the cost and installation of a solar array, especially Tesla's pricier solar roof option. And that's giving you complete independence from the electric company.

I talked to a rep about a solar solution and he understood my concern for wanting to go "net zero" since it feels like locally, the power company is devaluing what you put back into the sub-system more and more. He explained that more and more people exploring their alternative energy solutions are interested in these battery/storage systems for the exact same reasons. With a minimum investment of about 30k or 40k for a whole-home solution, a lot of people don't trust that their power fed back into the grid won't be devalued over time (at least a rate higher than the natural decay of battery technology).

I think the latter is more feasible without too much wind, since solar predictably goes to zero when demand is lowest. I don't think it's at all clear that a grid with high amounts of wind instead of nuclear would be cheaper.

And with a smart distributed grid, it's not just storage that makes sense locally - it's generation. Put a solar roof on the big box store, attach a storage system, and have a mostly self-sufficient system. And if it's generating surplus, sell it! Buy only when it's needed.

Meanwhile, poor developing nations or rural areas that don't have the capital or the chops to build giant nuclear plants can easily invest in very small scale projects. Go to some remote village, put up a wind turbine and a compressed air tank you can just bring in on a truck. Now that village has power! It may not be as financially efficient long-term, but by increasing the potential productivity of remote areas, it can pay for itself easily at the local level.

It's an exciting thing to see.

As we move to solar, electricity will become very cheap in the day and very expensive at night. This will create the required capital to create storage solutions in houses and factories. Also you don't need a portable battery when installing it at home, so I think the cost could be reasonable.

So with SolarCity at least, the focus seems to be on community storage, where the grid of replaceable batteries is shared by neighbors on the same cul-de-sac/block/street/community/town. Long-term this is also insurance against net metering going away (which utilities will probably lobby through successfully at some point). Via community storage neighbors can start selling to neighbors.

However, someone still needs to maintain the neighborhood storage system, manage billing for produced/consumed kWh, run the actual wires to/fro storage, at which point we've re-invented the utility company, just at much smaller scale.