I imagine in most places it'd be cheaper to buy an acre of land on the outskirts of town, or to rent an acre of otherwise unused rooftop from your local big-box store, than to build a barge with equivalent deck area; Wikipedia informs me for example that a Nimitz-class aircraft carrier has a deck area of only about six acres.
Land-based solutions also let you plug directly into the grid rather than futzing with also-expensive battery storage.
buy an acre of land on the outskirts of town
Opportunity cost. 15 years later that is suburbia. (And the current suburbia is a slum. Never buy a house unless you are 95% sure this won't happen!)
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.