Not long ago, having solar panels on residential roofs was a novelty, now Global Sources calls them mundane. Massachusetts added 340 MegaWatts of solar production in 2015, ranking it fourth nationally*. The state now has enough solar energy to power 191,000 homes and that number is expected to more than double over the next five years, partly due to more competition and lower prices – there are about 450 companies servicing the Mass solar industry and installed photovoltaic system costs have fallen 66% since 2010. So you may be wondering, Should I be using solar energy to power my home? This begins a multi-week series to help you answer that very question.
Lets start with the easy stuff: Can you add solar panels to your house and will it be worth the cost? Happily, if your home is in Massachusetts, you already have an advantage. Between the relatively high electric rates and the number of incentives available, the Bay State is a great place for solar – Number 1 in the country according to SolarPowerRocks.com
There are six major factors to consider when evaluating your roof for solar panel friendliness:
Age of roof – Solar systems can last for 25 years or more, so if your roof is in poor condition when the panels are installed you may have to remove the panels to service the roof at some point. If your roof is older or not in good shape, it may be easier (and cheaper) to replace the roof first.
Type of roof – Solar panels can typically be installed on most roofs including standing seam, shingle, rubber/vinyl, and clay tile (the method of attachment may vary depending on type). The two major types that arent compatible are slate and wood roofs.
Roof size – Your roof must be large enough to install enough panels to support your needs. According to EnergySage.com you typically need 100 square feet of roof per kw of energy needed. If you dont have that space in one area, you may be able to fit small panels into different parts of your roof potentially at a higher cost.
Roof angle – Flat roofs are typically fine for solar. The ideal angle for Boston (and towns with similar latitude), according to SolarPanelTilt.coms formula, is 35 degrees for peak efficiency. Youll need a minimum of 15 degrees for the panels to be self-cleaning and more than 40 degrees will decrease the amount of energy produced.
Roof orientation – Using a compass, determine the direction that your roof faces. With a flat roof, the panels can be placed at the optimal angle. For a pitched roof, ideally one side of the roof will face south, affording maximum sun exposure, but panels are efficient enough now that even an east/west facing roof will typically still be cost effective. Generally speaking, unless you have a shed style roof (where the whole roof is sloped in one direction) that faces north your roof orientation is probably okay.
Obstruction – Check is how much of your roof is shaded. Trees and other buildings are the most common factors. Observe your roof during different times of day and year to see how the roof fares with the changing position of the sun. Hopefully youll be able to get a good sense of this from walking around your building and looking to see if, where, and when shadows are cast on your roof. If youre not able to see the roof easily, check GoogleMaps earth view or a similar program to see if there are trees or other buildings around that could potentially cast shade on your roof at various times.
If you determine that your roof is solar friendly, you are ready to move to the next phase, evaluating the various methods of acquiring the panels. Be sure to check in next week to learn more about your options!
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