> The strategic goal of "dumping" is to drive competitors (the example here being the US solar panel industry) out of a market

Which makes very little sense, because the US solar panel industry is practically nonexistent. There are some companies that do last-stage assembly of solar panels in the US - probably to meet "made in USA" requirements - but the solar cells themselves are almost all made overseas.

In short, there's nothing there for China to dump on - the US is not a competitive threat to China in this sector. All indications are that Chinese solar panels are cheap because they're being manufactured in immense volumes to help meet China's own energy demands. The international sales are a bonus, not the primary goal.