The Parallel Hybrid Drive System seems like it is a Prius which is basically a Combustion engine with an electric motor assist with minuscule battery and a very complicated system and a pain to repair. As opposed to the Full Electric system (Series drive) which can be charged with either solar or generator which seems like the more reliable and system to me. I've always tell people the Prius is a scam. no mechanic likes touching it, overly complicated, and no gain in anything. Its mostly an engine. Either go all engine or all electric is what i tell people when they ask for car advice and i feel the same way about boats. There are some full electric boats that have kept a generator on board which they found they never had to even use because the batteries were kept well charged with their solar and they ditched engine. Also some electric drive system lets you turn each individual propeller 360 degrees for an extreme maneuverability as well as point the props forward to generate electricity back into the batteries. A full electric drive system is extremely expensive and not economical in todays battery costs. Even the mass produced Tesla batteries are having a hard time bringing cost down. A plain simple combustion engine on either side is the most simple and economical choice for todays boats. A hybrid system, is just plain to much unnecessary complications.