Investigating updating community architectural standards for a homeowners' association; & was wondering...

Just how efficient are roof-based solar panels?

Looking at various manufacturers & power ratings (125W to 200W)...the costs range from $1000 to $2000 per panel.

So...if our residents were to be permitted to install Solar Panels on the roofs of their townhomes, would they have to install a dozen or so panels just to run a hot-water heater?

We're trying to get an idea of how beneficial this would be to the community & the residents. The roof areas here are only about 25' X 25'; & if they needed more than a few panels to generate a worthwhile amount of energy, we would run into an aesthetic problem.

Are there any cost vs. efficiency specs available on the web? We are in NJ.

Thanks,

mark4man