Latest Discussions : Electrical & Lighting


08:17AM | 03/30/06
Member Since: 07/20/05
17 lifetime posts
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.




10:41AM | 03/30/06
Member Since: 04/25/05
1915 lifetime posts
Efficiency is an engineering term that has to do with the ratio of useful energy out of a system vs the energy available to it.

IIRC current solar cells are about 4-6%. Ie the percent of solar energy that is converted to electrical.

I don't have the numbers but I suspect that direct heating of water with a solar water panels will be much more efficent.

I think that you are looking for effectiveness. That is the suitability of a given system for a given application. Much more subjective.

What is a "worthwile amount of energy" depends on your local energy cost, your local (and federal) incentives (rebates, tax credits, net metering), climate, and your roof orientations.

Within that last few months Fine Home Building has had an article on installing solar electric. And either they or the Journal of Light Construction had one of the difference type of solar water heating systems.

But there are maganizes and website dedicated to alternate energy. A google will find them.

Along with a lot of work by the Department of Energy.


01:40PM | 03/31/06
Member Since: 07/20/05
17 lifetime posts
Thanks, Bill.


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