Good solar designers assess climate particulars to enhance system performance. Climate includes elements such as temperature, precipitation, and wind speed, among other things. When determining whether solar power is right for you, take a look at the following in your climate:

  • Sunlight: Climate dictates how much sunlight you can expect annually. The Southwest gets the most sunshine per day in North America, and Canada and the northern states get the least. The sun is higher in the sky in the southern states, so the days are longer. The figures at the end of this article outline the average number of hours of sunlight that different regions of the United States get throughout the year.

  • Snowfall: You want to locate your panels so they avoid being inundated with heavy layers of snow. For example, some locations on your roof will experience very shallow snow buildups compared with other parts of your roof.

  • Cloud cover: Ultimately, cloudy regions provide less sunshine, making solar systems harder to justify. But that doesn't necessarily mean that solar is uneconomical, so if you live with a lot of clouds, don't despair.

  • Smog: Air pollution and smog affect the amount of sunlight you can expect to receive. If you live in an area with heavy air pollution, expect less system output over an extended period of time.

  • Air density: You get better solar exposure in the mountains than near sea level simply because the air is thinner and scatters less sunlight. You can make an approximate estimate of how clear your air is by simply observing how blue the sky is on a clear day. Thick air scatters more red light, and so the appearance of the sky is less blue and more white.

  • Temperature: With PV systems, the lower the temperature, the happier the semiconductors, and the greater the output. You can get more system output on a cold, clear day than a sunny day.

  • Rainfall: Wet, humid environments tend to cause corrosion in metals. Electrical connections are particularly susceptible, and they either fail entirely or their integrity is compromised, resulting in poor system performance. It's very important to seal equipment junctions properly.

  • Frequent fog: If you're living in an area that's foggy and misty in the morning, orient your solar panels more westward to optimize the amount of sunlight you can achieve over the course of a day. Fog also causes a lot of moisture-related problems, such as corrosion.

  • Wind: If you have a lot of wind, you need to consider where you mount your solar equipment for a couple of reasons:

    • Wind can tear equipment off of its mounting hardware and result in expensive repairs, not to mention dangerous conditions. Mounting schemes all have wind speed specifications.

    • Wind cools surfaces very efficiently. Solar water heating panels may heat the water very effectively, but it doesn't make much sense to install expensive solar panels without addressing wind cooling first.

Part of assessing climate is what you want your solar system to do for you. If you have a cabin in northern Minnesota, you probably won't be there much in the wintertime. And then you'll heat it using renewable wood. In the summer, you don't need to cool, and all you want to do is obtain some nighttime lighting and run a small, efficient refrigerator. In this case, a modest, off-grid photovoltaic system with a battery backup can do the job.

Hours of sunshine in the United States in the fall and winter.
Hours of sunshine in the United States in the fall and winter.
Hours of sunshine in the United States in the spring and summer.
Hours of sunshine in the United States in the spring and summer.