There’s a lot to see at the Fraunhofer Center for Sustainable Energy Systems in a rehabbed old building in Boston. Fraunhofer is a big German research and development non-profit organization, with a couple of branches in the USA. They have been working with solar power for years, and last year held the record for making the world’s most efficient solar cell. Now they are looking to reinvent the way solar panels are installed.
Christian Hoepfner, the director of the center, explains that much of the cost of installing photo voltaics is in the frame they are mounted on, and in the connections, the wiring of it all together. This needs about 26 hours of a qualified electrician and a lot of work by the roofer, and presently totals about $ 4.90 per watt installed.
They have redesigned the solar panel, mounting the photovoltaics on a light, flexible substrate, which has an adhesive back that essentially glues it to the roof. Because most building codes specify roof sheathing that is designed to allow for the weight of a second layer of shingles, these panels should be able to be installed without any engineering expenses or approvals because they weigh pretty much the same as shingles.
A simple connector attaches one panel to the next, which then feeds to a packaged inverter.
Then it gets really clever: an electrician can pull off the meter head (homeowners aren’t allowed to do this) and stick a special connector in between the base and the meter head. Then the standard universal car-charging plug is stuck right into the inlet. Nobody has to rewire their house or even go inside. Total installation time: about 10 hours, and a cost of about $1.50 per watt. And it’s all as easy as falling off a roof.
I have some reservations. I don’t think homeowners should be climbing over their roofs without safety harnesses, and hope that they will still recommend professional installations. I am not crazy about the idea of gluing things to shingles; are there going to be moisture and maintenance issues? What about freeze-thaw issues? I would have preferred that it actually was inserted under the tab of a row of shingles at the top so that it actually acts as a giant shingle. And what about velcro instead of glue? And there is more to American housing than low-slope roofs on suburban bungalows, what is the cheap and cheerful solution for them?
But I like the thinking. It’s not just a technical problem they are solving, but they are looking at the regulatory issues, code compliance, safety and ease of use. It’s a big complex package, trying to make something simple.