I am brainstorming issues for a seastead design.  Most of the outside of the seastead will be solar,
as the electricity is needed to run propulsion and everything else.  I am wondering if it would 
make sense to use some "solar roofing" system instead of separate roof and then solar.
Are there solar roofing systems that could work in a marine environment?
What do they cost per sq-meter?
Is it usually cheaper than having a separate roofing and solar to have a combined system?
How long do they last?