@Opus 17 thanks for your answer!
I'm pretty sure that the solar skylight are eligible, I got some quotes from Solatube and Velux, and they both agreed on that. As mentioned in the thread I linked, Velux has a page which states it explicitly: http://www.veluxusa.com/help/tax-credit
I know it's not a proof that it's legally accurate, but I would be really surprised if they were advertising this for a couple of years if it wasn't true. Also I found a couple of thread with people succeeding in claiming the tax credit for that (even though I know it's still not a legal proof).
My question was solely about the possibility to claim both, which you answered clearly, so, thank you!!
