Yardley Voice – Going Greener Solar Column – June 2011
Shining the Light on Solar Energy — An Introduction: Solar Power, Past and Present
by Mark Bortman
I was in the Oxford Valley Mall for just an hour the other day. When I got into my car, the steering wheel was too hot to touch! WOW, is that solar power strong! Although the sun is more than 90 million miles away, it is so powerful that the solar energy contained in the sunlight that hits the earth in just one hour is more than the total energy consumed by the whole world in a year.
Can we capture that energy and transform it to a useful form? There are two distinct technologies, solar thermal and photovoltaics (PV), with very different beginnings, that do just that.
Solar thermal systems convert the sun’s energy to heat. They have been used for thousands of years. Historical records tell of solar technologies as far back as the 3rd century B.C. The ancient Greeks used magnifying glasses and mirrors to concentrate the sun’s rays to light torches and as weapons (in 1973, the Greek Navy did a recreation and successfully set a wooden ship on fire from over 160 feet away!); the Romans in the 1st to 4th century A.D., used the sun to heat their bath houses; the Anasazi Indians of southern Colorado were masters of efficient use of solar energy to heat their houses; 18th century explorers in the New World used solar cookers to heat their food.
In 1891, an inventor in Baltimore, Clarence Kemp, patented the first commercially available solar water heater for homes and businesses.
More recently, there was a big rush on solar water heating after the oil crises of the 1970’s. Many of these systems are still going strong after 30 years. Although the basic concept of solar water heaters has remained the same to today, technology has greatly increased the productivity of these systems.
Photovoltaics (or PV), on the other hand, directly converts the sun’s radiation into electricity. The photovoltaic effect was first discovered in the mid-19th century and PV panels powerful enough to run electrical equipment were developed about 50 years ago. It is only in the past 15 years or so that PV has made the jump from NASA to the mainstream. It is commonly said that just 100 square miles of PV panels could fill the electric needs of the country.
Our ancestors benefited from solar energy and, because of innovative technologies, you and I can use it, too. I am pleased to have the opportunity to be starting this column about the happenings in the solar industry. My future articles will reflect the common questions I get from my customers about home and commercial solar installations and solar power. If you have any specific questions or issues you would like me to address in upcoming columns, please email me at mark@exactsolar.com.