Invest in Solar Energy Wisely

Before you invest in solar energy, check out these tips on assessing your unique solar window to decide if solar energy makes sense for your site.

| March 2015

Solar panels

Solar energy is a popular and rapidly growing industry, and it's well worth the investment as long as you ensure that solar energy is appropriate for your site.

Photo by Fotolia/underworld

Solar power is rapidly becoming mainstream, and the options for investing in solar energy are staggering. A Solar Buyer's Guide for the Home and Office (Chelsea Green Publishing, 2010), by Stephen and Rebekah Hren, is the perfect resource for navigating solar power system options successfully, from understanding how solar systems work to knowing the right questions to ask a professional installer before choosing a system. The following excerpt from chapter 2, “What’s Appropriate for Your Site,” deals with finding the solar window of your site.

Free energy from the sun streams down upon us, and we need to take advantage of it! But to make an investment in solar worthwhile, you must have sufficient access to that free energy. Neighboring buildings, trees, and terrain can all be an impediment to sufficient sun. After all, you can’t live a life powered by the sun in the shade! Even if your home and yard are completely shaded, there are still opportunities to invest in solar energy (and especially solar electricity) through things like green-power programs.

To analyze a particular location such as your south-facing roof space or a sunny spot out in the yard, you’ll need to take stock of the six primary factors that affect any site’s unique solar availabil­ity—its solar window (See diagram in the slideshow). Doing so before bringing in installers to get project bids ensures that you understand what the potential limits and complications are for any solar installation at your site. These six factors are:

1. Existing vegetation and its potential growth
2. Average seasonal insolation and climate extremes
3. Position on Earth (latitude) relative to the sun
4. Orientation of your home and other existing structures relative to solar south
5. Terrain such as mountains and other potential obstructions such as complicated roof designs
6. Available area or square footage

Getting Acquainted with Your Solar Window

If you haven’t already, it’s time to take stock of where your home, building, or office is in relation to the sun. When you get up in the morning, and over the course of the day, watch where the sunlight comes in and where it goes. Pay attention to where it is at midmorning, midday, and midafternoon. Which exterior walls are shaded? When does the roof get sun in the morning and when does it stop in the evening? What surrounding structures cast shad­ows on which part of your home, and at what times of the day? Additionally, which parts of the building shade other parts, such as dormer windows, vent pipes, and chimneys?

As the seasons change, many of these things will gradually change with them. When the sun sinks into the sky during winter, the number of obstructions will likely increase. On the other hand, trees will lose their leaves. Consider how these changes would affect efforts to access sunshine at that time of year. In midsummer, pay attention to the unexpected solar path that starts with the sun to the northeast at dawn, high up overhead at midday, and setting in the northwest at dusk. Each time you watch the path of the sun over the course of the day, remember that it will follow this exact same path on the other side of solstice, so that May 21st will be the same as July 21st, April 21st the same as August 21st, and so on.

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