August 24, 2010

Options for Photovoltaics

When we began this journey, we set upon a road to produce enough power to run a modern home – no excuses. It does not make sense to promote a new way of building that provides fewer amenities or that looks like an industrial building plopped in a residential neighborhood. The Folly has lights – indoors and out, ceiling fans, a whole house fan (this is Florida, after all!), air conditioning (again, a nod to our location), refrigerator, an induction cooktop, dishwasher, and washers and dryers. All these features run on electricity. According to Matt Gore, the architect on the project, about 12 KW will be more than sufficient. 

After we’ve done all we could to seal the envelope, provide air flow, and reduce consumption via the use of LED light bulbs and heat recovery pumps, we still have a big draw – air conditioning is energy intensive. How can we accomplish this? While other sections of the country can use geothermal or wind energy, the most available power source in this part of Florida is the sun. At the moment, the options for generating solar power are:
We looked at all three.

There are differences in costs and aesthetics. The standing seam metal roof looks appropriate in this beachside community. Either the mounted panels or the thin film works with such a roof. Since I objected to the “look” of a dozen or so panels mounted on my roof, we took a look at the thin film. This is an elegant system where the photovoltaics are glued between the seams and the hot water heating system runs under the metal roof. Very neat. The film is most efficient when in lengths of over nine feet. Unfortunately, the Folly has enough south facing sections that measure over nine feet to produce only 3.5 KW. We had already decided that we needed more than that. So this option was set aside.

The two remaining options were PV panels mounted on a metal roof and a tile roof with embedded PV. My aesthetic preference was for the tile but I wasn’t willing to ignore costs. As it turned out, the mounted panel system that produced 12 KW cost 15% more than the tile integrated panels. A happy day! The more pleasing option cost less!!! I could please both my eye and my bank account!