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Last Post 3/18/2013 10:38 AM by  Claire Raftery
Solar Energy on rainy days
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3/17/2013 9:12 PM


    I heard that you can't use solar energy on rainy days. Is that true? And can places where there are lots of clouds and rain still use solar energy?

    Sad in Seattle

    Tags: solar energy, UV rays, sunburn, clouds

    Kelly Larson

    New Member

    New Member

    3/18/2013 10:14 AM

    Hello Sad,

    Part of why you're sad may be that the sun's intensity is so low in a rainy place like Seattle. This can trigger Seasonal Affective Disorder, (also called "SAD") which can cause depression.

    The sun's intensity as experienced on the earth is described in three ways, Global, Diffuse, and Direct. Global solar exposure is the total amount of solar energy falling on a horizontal surface. Diffuse solar exposure is the total amount of solar energy falling on a horizontal surface from all parts of the sky apart from the direct sun. Direct solar irradiance (also referred to as direct normal irradiance) is a measure of the rate of solar energy arriving at the Earth's surface from the Sun's direct beam, on a plane perpendicular to the beam, and is usually measured by a pyrheliometer mounted on a solar tracker. The tracker ensures that the Sun's beam is always directed into the instrument's field of view during the day.

    Notice in the figure below how these three track on a sunny day, as compared to a cloudy or partly cloudy day.

    These is often confusion about this subject on a partly cloudy day, because where the sun is shining through the very edge of a cloud, the cloud can become like a magnifying lens. We see peaks of very high intensity at those times, as shown in the afternoon here.

    So if you are sad, you may have SAD, and need light therapy. “Full spectrum” lighting used indoors can help to get you the “sunlight” you need to be happy again.

    Blessings for a “brighter” tomorrow,


    Claire Raftery

    New Member

    New Member

    3/18/2013 10:38 AM
    All you need for solar panels to work us ultraviolet light! So they can definitely be used in cloudy places, although they may not be as effective as very clear places. The clouds in our atmosphere, which are pretty good at blocking out visible light but not so good at blocking out UV rays (yep, that means you can get sunburned on a cloudy day). So there is no need to be Sad in Seattle, you can be Sunny in Seattle if you get testing with some solar panels. Hope this cheers you up. Claire
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