The tariffs, which are quite low, are based on the amount of subsidies the Chinese companies get from their government. The second tariff, an anti-dumping duty, is coming soon.
I guess by that logic, China could put a tariff on products for any US company that gets financial help from our government. China probably will retaliate in some way and then we’ll have a pointless and self-destructive trade war.
China may or may not be dumping but another view is, don’t blame China for our own solar power incompetence.