By Michael Mariotte

If you read our piece Tuesday on Tesla’s new PowerWall battery storage announcement, but spent the past three days thinking about whether you wanted to get one for your own home, well, you waited too long.

According to several reports, Tesla has sold 38,000 PowerWalls since its announcement a week ago, and is now sold out through mid-2016. Not terribly surprising since its Nevada Gigafactory to manufacture batteries for both its cars and electricity storage use won’t even be completed until then.

Perhaps more significantly for the future of clean energy, Tesla also has sold 2,500 of its larger PowerPacks. Those are the systems designed for commercial, industrial and utility purposes. And those 2,500 batteries will surely store a lot more power and enable a lot more renewable energy deployment than will the larger number of home systems.

That’s especially true since, as several media outlets reported (perhaps a little too gleefully), the home systems aren’t–yet–particularly useful for going off the grid or even enabling rooftop solar owners to store their own power generated during the day and use it at night.

SolarCity, the rooftop solar company of which Tesla’s Elon Musk is chairman, isn’t even marketing the smaller (7 kw) battery that would serve that purpose. Again, not yet.

All batteries are designed for specific purposes. In this case, the 10 kw PowerWall is intended only to handle the occasional power outage experienced by the grid and thus enable consumers to have some (although a quite small) amount of backup power to keep some essential systems running. It is designed to cycle only about 50 times/year.

The smaller 7 kw battery is designed to cycle much more frequently–a few hundred times per year–making it suitable for rooftop solar owners to store their electricity and use it on a daily basis. But SolarCity won’t market it right now because current net metering policies (in which rooftop solar owners sell excess power back to utilities) established in most states make more economic sense for homeowners than saving their power and using it later.

Some other companies, and there are a growing number planning to sell the PowerWall, may market it for the purpose of homeowner energy independence, but for the most part, that’s still a few years into the future.

So does all this mean that Tesla, and electricity storage generally, is not the fundamental game-changer, the new paradigm, that we and many others described it as just a few days ago?

Not at all. As we wrote Tuesday, “What Tesla is doing–and we’re just at the very beginning of this transformation–is changing the entire nature of electricity generation and distribution.” Let’s emphasize “the very beginning of this transformation.”

The significance of Elon Musk’s Tesla battery-powered announcement is two-fold: first, Tesla has dramatically lowered the cost of electricity storage, and has done so even before its Gigafactory is in operation. Mass production will lead to both lower prices and greater capacity. Tesla competitors will also have to up their …read more

Read more here::