A search for "Interview with Jerzy Peszke 30 January 2015" gets an interview where Peszke says that the batteries weigh 20 kg (versus 32 kg for the FES). Of course, it is not clear how the GP 14 gets the same range as a FES glider like the Silent Electro 2, yet has batteries that weigh only 2/3 as much.

Thanks. I see that he states the power plant can produce 3 launches to 500m. I heard that the Silent does 3 launches as well but don't know the height nor reserve power.

This is an exciting glider and can't wait to see more videos of it in action.