Which “solar isn’t good enough” crowd are you talking about? I have never heard of anyone saying that we should build less solar capacity just because a 100% solar powered grid may not work best in all areas. Rooftop solar especially is a non-issue for anyone who wants to move off fossil fuels.

The only time I’ve seen people arguing against solar is in locations where winter drops the solar energy production for half the year. Even then, people are talking about grid scale installs and alternatives, not rooftop.

Who said the device based service has to be closed source?

It says right in the article that it supports having up to 20 of these batteries in parallel, which gives you much more than 20kwh.

The article doesn’t really mention it, but it’s also partly due to the OEMs cancelling a lot of new programs over the last year. Running existing equipment, which has already paid itself off, for a few extra years leads to slightly cheaper vehicles.