Wind and solar hybrid systems: A complementary relationship


Wind and solar hybrid systems: A complementary relationship

There has long been a debate about which source of renewable energy is superior: wind or solar. In recent years however, it has become clear that one source most often does not outperform the other. Instead, there exist seasonal benefits to each source. It has been determined that both wind and solar have compelling benefits within their seasonal range.

A wind/solar hybrid system is fully integrated and designed to provide improved system efficiency. Throughout the seasons, hybrid systems provide a balance and increased energy production when both wind and solar energy are available.

To understand the benefits of a wind/solar hybrid system we must first examine the seasonal fluctuations of the wind and Sun.

Why is there more wind in the winter?

The winds annual productivity reaches its peak in the winter months. The Earth’s atmosphere is essentially a container filled with gasses (air). The metric used to measure the density of air is known as barometric pressure. High-pressure air migrates to lower pressure pockets in an effort to establish equilibrium. The greater the difference between the high and low pressure, the faster the wind speed of the equalizing air.

Short, Nicholas M. FIG07_006.jpg. Digital image. ATMOSPHERIC CIRCULATION; WEATHER SYSTEMS. Nasa. Web. 13 Oct. 2011. <rst.gsfc.nasa.gov>.

The atmosphere is in essence divided into several layers. When air closest to the warm Earth’s surface is heated, it becomes less dense and expands. This expanding warm air displaces the layers of air above it. This means that the atmosphere in this area has low pressure, based on the lack of air density (barometric pressure) on the surface of the Earth.

Cold, compressed air on the surface of the Earth leaves a void above it, which is filled in by air in other areas of the atmosphere. On the Earth’s surface, there is high pressure caused by the weight of the dense layers of atmosphere above.

Air flow diagram

Airflow.jpg. Digital image. Noaa.gov. Noaa, 05 Jan. 2010. Web. <http://www.srh.noaa.gov/jetstream/synoptic/images/airflow.jpg>.

The difference between the high and low daily temperatures in the winter is greater than that of summer months. This causes a more dramatic transfer of air from high and low pressure, resulting in increased wind.  

Why is there more sun in the summer?

The Earth orbits the Sun once each year (365 days). Each day consists of a single rotation of the Earth around its tilted axis. Each hemisphere, top and bottom of the Earth, is in its summer when it is tilted toward the Sun. During the summer in the Northern hemisphere the Southern hemisphere experiences its winter and visa versa. The climate changes resulting from Earth’s axis in relation to the sun are known as ‘seasons’. Because each hemisphere tilts towards the sun in the summer it receives more direct sunlight. When each hemisphere tilts away from the sun in the winter, there is less direct sunlight.

Earth Orbit diagram

EarthOrbit.png. Digital image. The Summer Solstice. National Weather Service, 27 May 2011. Web. <http://www.srh.noaa.gov/abq/?n=clifeatures_summersolstice>.

Because the wind is most powerful in the winter and the sun is most powerful in the summer. A combined or ‘hybrid’ wind and solar system makes the most of the resources available, regardless of the season. Hybrid systems combine the inversely productive wind and solar seasons, providing a consistent and dependable source of energy throughout the year.

The image below depicts predicted wind and solar energy for Southwest Windpower’s Skystream Hybrid 6 at several locations. Notice the inverse, yet complimentary relationship of wind and sun energy.

Wind and solar energy estimate for Kingman, AZ from Skystream Hybrid 6

Renewable energy companies are continuously developing strategies for providing their customers with the best energy solutions. As an industry leader, Southwest Windpower is setting the pace with several new wind-hybrid systems, starting with the Skystream Hybrid 6.

To find out how a mix of solar and wind energy can work for you, get a free Sitelook assessment.


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