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Satellites and Technology

How Do Clouds Affect Solar Energy?

Life on Earth relies on energy – such as light and heat – from the sun. In fact, energy from the sun, called solar energy, is the most abundant energy resource on Earth. According to the Department of Energy, the amount of sunlight that strikes Earth's surface in 90 minutes is enough to meet the entire world’s energy needs for a full year.

You can feel the sun’s energy as heat and see it as light. But how do we harness that energy to cook dinner or charge a phone? Solar panels!

Solar panels on dirt ground under a cloudy sky.

Solar panels in Jurupa Valley, CA. Credit: Photo by Janet Purchase/US Dept of Energy

You may have seen solar panels on the roof of a house or other building. These solar panels capture light energy from the sun and convert it into electricity that can be used by the people inside. Some power companies use solar panels as a source of electricity, too.

However, clouds can block light from the sun. So, do clouds affect the creation of energy by solar panels? Yes, but it depends on the types of clouds and where those clouds are in the atmosphere.

When sunlight hits low clouds, a lot of that light – and heat – is reflected back into space. When sunlight hits clouds that are high in the atmosphere, those clouds reflect less sunlight energy. However, these high clouds also trap more heat.

Illustration of arrows, representing sunlight, getting reflected by high and low clouds. The high clouds are reflecting a smaller arrow than low clouds.

When sunlight hits low clouds, most of that light is reflected back to space. High clouds reflect less sunlight energy. Credit: NASA/JPL-Caltech

So, if you live in a place that commonly has a lot of low clouds, solar panels might not be able to produce as much energy as they would somewhere else.

However, certain cloudy conditions can be great for the production of solar energy. One example happens when ice crystals inside of high-altitude clouds cause the sunlight to appear brighter than usual. This phenomenon is called “cloud lensing” because the high clouds act as a lens, focusing the light in a certain region.

Is more sunlight better for solar energy production?

More sunlight means more energy, but that’s not always a good thing.

People who manage electrical grids – the electricity networks that connect electrical producers with consumers – must keep a careful balance between the energy they generate and the energy their customers consume. This balance is important because unexpected surges in the amount of available electricity can damage electrical devices, or even trigger a power outage. So, producing more solar energy than expected could potentially cause big problems.

How can weather satellites help?

From their orbit 22,300 miles above Earth’s surface, satellites in the Geostationary Operational Environmental Satellites – R (GOES-R) are constantly keeping an eye on Earth’s weather—including clouds.

GOES-R Series weather satellites measure cloud properties that can help energy companies predict solar energy production. They can use this information to track and predict the movement of clouds and estimate the amount of sunlight that will reach solar panels.

GOES-16 true color imagery over the Continental U.S. on 14 May 2020 shows NOAA cloud top height retrievals (in km, color key at bottom of graphic) atop GeoColor imagery. Cloud top height information is useful for understanding the geometry of where these clouds will cast shadows upon solar farms.

Colors on the left side of this GOES-16 imagery of the Continental U.S. on May 14, 2020, represent measurements of cloud top heights in kilometers. Cloud top height information is useful for understanding where these clouds will cast shadows on solar panels. Credit: CIRA

Solar energy is growing in popularity. Information from weather satellites can be important in deciding the best spots to capture it. For example, information about cloud formation can help in determining where to build solar power plants and what type of solar panel technology will capture the most energy.

Another way that weather satellites help with energy issues is in the detection of space weather. Space weather is caused by energy and charged particles being released by the sun. It can also impact the performance of the power grid. The GOES-R Series satellites have space weather instruments that can detect approaching space weather hazards. This can help communities make plans for possible space weather-related power outages.