David Brin, in a comment on his blog describes Elon Musk as a ‘successful innovator’ rather than an investor or government subsidy truffle pig. Brin seems to be under the impression that Solar City “put up 2 million solar roofs”.
As best I can find, Tesla has only installed a few thousand ‘Solar Roofs’. Electrek reported in 2022 that Tesla was doing 23 installs / week, and was pausing installations. Tesla started mass market deployments of the product in 2020.
Tesla bought SolarCity in 2016. SolarCity does mainly ordinary solar panel installations, and Tesla uses combined figures to make it seem like the ‘Solar Roof’ product is more successful. The Tesla ‘Solar Roof’ costs several times more per watt that ordinary solar panels, and doesn’t make economic sense.