Last year, First Solar announced it could take an impairment charge of between US$500 and US$700 million in the phasing out of the thin-film solar panel model it was producing at the time, its flagship Series 4, and speed up the development of the new model, Series 6. The Series 6 was expected go into production in 2018, and according to comments at the time of the announcement, would help First Solar to gain a competitive edge in a world of falling solar panel costs.

But what about the proposed tariff?

This is where it gets complicated for First Solar because it's not black and white—and when it comes to stock prices, well, it depends on who is paying attention and what they're paying attention to, exactly.

It would seem to make sense that a tariff on imported solar modules and cells would benefit First Solar, but not necessarily because it would boost sales by eliminating lower-cost imports.

On the contrary, a tariff on Chinese solar module and cell imports would benefit First Solar by allowing it to continue to produce its own modules and cells in Malaysia while competitors grapple with higher import prices. Why? Because First Solar does not use crystalline silicon for its modules. It uses cadmium telluride for its thin-film PV panels, so the tariffs, which specifically concern the more popular crystalline silicon solar products, won't affect it.

But let's not get ahead of ourselves. First Solar's Series 4 is what is being produced in Malaysia, and that production capacity is being idled. So this immediate benefit of the tariff isn't as great at it looks on the surface. It's preparing for the launch of the Series 6 now, and it may have to reopen one idled factory in Vietnam to respond effectively to a hoarding urge in response to the ruling. This would add to the company's cost burden in the short-term, but over the medium and long term, it could be a benefit—if tariffs go through.

Right now, the drop in FSLR's stock price reflects the general confusion as to what this means for all solar stocks, and the reality hasn't yet set in regarding this company's future in a new regulatory environment. It also reflects the fact that no one can be sure if these tariffs are going to see the light of day, given the level of opposition from the industry they are meant to protect.

In the medium and long-term, First Solar could turn out to be one of the very few winners from the Suniva/SolarWorld case, so even though it's lost over 5 % this week, there's room for a reversal.