But from the perspective of people in the US who want solar panels, or Chinese producers of solar panels, it definitely is a bad thing.
Also, the link you supplied doesn't mention a word about solar--so punishing solar companies in order to "get back at" wind companies just doesn't make sense. Moreover, it isn't the case anymore that the Yuan is unambiguously undervalued. Many things are more expensive in China (in exchange-weighted nominal terms) than in the US, such as cars, electronics, etc. Also, in terms of the current account surplus, it is considered "normal" now [1].