Solar Assessment at the Krafts

My aunt and uncle are planning to renovate and expand their kitchen and asked me if there is an opportunity for solar photovoltaics as part of the project. The expansion will include a new addition to the southwest corner of the home, which is located in Winchester, Massachussetts. Unfortunately, early in the morning the sun will be blocked from the new single story roof by the existing building, which is three stories above grade. There will also be some time in the spring and fall, when the sun is still lower in the sky, when the neighbor's trees will partially shade the new roof (shown in the picture below without leaves). On average, the area of the new roof will receive sunlight about 66% of the time in the location shown in these images. This perecentage improves a little bit further away from the existing building, but will then be affected more by the trees (and the leaves that will appear shortly).

The analysis was done using a Solar Eye digital camera, which uses a fish eye lens to take a 360 degree photo of the horizon. As long as the camera is set to point towards due south, is leveled before shooting, and has the coordinates of a nearby location (the city of Boston in this case) entered into it's computer, the device is able to overlay the path of the sun and check for times of shading. I'll probably use the PV Watts program to evaluate how much electricity would be produced if they were to put photovoltaic panels on the new roof. We'll also look at the tax credits and rebates available to help offset the initial cost. We'll also try to put a price on the value of creating their own renewable energy on the new roof just below the second floor bathroom used by their four boys and the education they'll receive as a result.

Photos by Lisa Cordner.