By David Verner of Adirondack Solar

For those of you who may have missed reading my article in the Summer issue of the Ecolocal Guide, I talked about Bill and Jennifer from Malta*. Bill and Jennifer live in a 2,100 square foot home and have 2 young children. As with many families today, they are environmentally conscious and also fiscally smart. Bill and Jennifer have an interest in installing solar at their home but have no idea where to start.

The first thing we need to discuss with Bill and Jennifer is their energy consumption. Have they replaced all their incandescent light bulbs with energy efficient CFLs? Do they have any old appliances that can be replaced with an Energy Star model? Are their home windows energy efficient and does the house have enough insulation? Once we establish the basics of efficiencies then we can start to evaluate how their home is oriented in regards to the azimuth. The azimuth is just a fancy word for seeing if the long portion of the roof faces south. The closer to true south the house faces the more solar gain it will have. Most homes do not face directly south but that is still Ok because the technology can still produce energy. The further away from true south though, the less energy produced.

Bill and Jennifer’s home faces “almost south” so they have a good orientation. Unfortunately, they have a dormer on the most easterly side of the house. This dormer casts a shadow on a portion of the roof so we will need to stay away from installing our panels in this area. If their home was oriented too far off south or if their dormer cast a shadow across the entire roof then we would evaluate putting the panels somewhere in their yard using a pole or ground-mounted system. Installing solar on the ground has its advantages and disadvantages, which we will discuss in a later article, but for now it looks like Bill and Jennifer can install a roof-mounted solar system.

Their roof is asphalt shingled and only 4 years old. If it was over 10 years old I would want them to replace the shingles before we install the solar. My next task is to measure any shading that may fall upon the roof from trees or things like a telephone pole. Since the sun moves across the sky differently depending on the seasons, I will use a shading analysis tool. This tool will give me a shading reading for the entire year. I can then calculate what that does to solar gain. Bill and Jennifer have a white pine off to the side of their yard that would throw a small shadow on the roof during the winter months. With a little trimming though, the tree will no longer throw a shadow and we will have full sun all year long.

Being fiscally smart, Bill and Jennifer want to maximize their investment, which is why they want to install photovoltaics (PV) first and then down the road contemplate installing solar thermal. The current State incentive program is only for PV to make electricity and not solar thermal for heating hot water. The household uses on average 450 kWh per month. Kilowatt-hours (kWh) is how the utility company measures electricity usage.

Now that we know how much electricity the household uses, we will compare it to how much square footage of PV modules the roof can support. Bill and Jennifer’s roof can support a 4 Kilowatt (kW) system, which should offer them 100% of their electricity usage. NYSERDA, which is the state authority that manages the incentive program, will offer a very generous incentive on this system. The total cost of this system comes out to $29,000. But because of the incentive program and State and Federal tax credits, Bill and Jennifer will ultimately only end of paying $7,650 out of pocket. For $7,650 Bill and Jennifer have secured their electricity power, with a life expectancy of their system to be over 30 years.

In the Holiday issue we will discuss how a pole or ground-mounted system would have worked for Bill and Jennifer if their home’s roof was not situated correctly or had too many obstacles casting shadows.

*You can read past issues at here.

David Verner is CEO of Adirondack Solar (ADKsolar.com), a solar installation company specializing in all aspects of solar technology including grid-tied battery backup systems and off-grid applications. He can be reached at 1.877.407.3356, This e-mail address is being protected from spambots. You need JavaScript enabled to view it