Friday, May 15, 2009

Solar Power!

We are very excited about the prospect of installing solar power on our house, something we were not sure we could afford. Through a new program that has just arrived in Massachusetts, we have signed up to have 4 kilowatts of solar panels installed on our roofs through what is called a power purchase agreement. The gist is that we pay very little up front ($1,000) and then sign a long-term power agreement with Sun Run Power, which charges us $0.14 per kilowatt hour for the next 18 years, which is about $.06 less than what we pay now. Even if electricity rates do not go up, we pay for the project in 6 years and then save money after that. If electricity rates go up, we save even more. And we expect that the 4200 kwh produced by these panels should provide more than half, maybe 2/3 of all our energy needs for the entire year! At least that's what we're hoping.

Alteris Solar was the local installer arm of this program and they came out a couple of weeks ago to do a roof analysis. Even though we have east and west facing roofs, their analysis showed that because our roofs are relatively flat, and we have very little shading, our production would actually be pretty good. We're very excited, given that our house will be all electric.

Exterior Foam Installed!

Scott and crew have made great progress in installing the 4 inches of exterior rigid poly-iso foam (from Iko Enerfoil) around the entire house. They have also attached wooden strapping, using 8 inch timberlock screws to ensure that the foam stays up and to provide a base to which the siding will be attached.

The foam was installed in two layers, staggered so the seams did not overlap, and then taped along the seams. The result should be an efficient air barrier and another R24 of insulation.

Apparently, the strapping was the most difficult and time consuming portion of the work, given that they had to pre-drill 8 inch holes into the studs and screw each screw individually.

The strapping also helps to provide a drainage plain behind the siding to allow water to drain away from the house. I have learned that this is a good way to do siding even if there is no added insulation.