One would think that a forward looking CEO, would have an idea on how many units he was planing to build in a calendar year and would have contracted a price for the materials needed to build those units far in advance of production.
If the product is so environmentally good and economical for the end user one would think welfare (special tax break) would not be needed to sell them and a slight rise in selling price do to a tariff would discourage potential buyers.
Remember, all products including those of PLUG competitors will also be victims of any tariffs and their production cost will also be rising.