About Solar Energy
The star (aka the sun) at the center of our planetary system is estimated to be 4.6 billion years old, and is likely to remain stable for another 5+ billion years. It continuously produces 384 yottawatts (that’s 384 followed by 24 zeros!) of energy, but only a tiny fraction of that reaches earth. At ground level, direct overhead sunlight provides ~1 kilowatt (kW) per square meter. Here in Northeast Pennsylvania, on average throughout the year we receive about 4 hours of direct sunshine each day, so that’s ~4 kWhrs of energy for every square meter of exposed area.
Sunlight (aka solar energy) hitting the earth has provided all the energy for nearly all the life that we know of, and is the underlying source for nearly all the energy humankind has ever used throughout our existence. Wind and ocean currents (and the water/rain cycle) move because of the difference in temperatures from sunlight warming various parts of the earth. Plants and trees collect sunlight, storing the energy as chemical bonds in their biomass. Animals, including humans, then eat those plants to gain energy. We harvest wood to build structures or burn for fuel. Decayed biomass, after millions of years under pressure within the earth, transforms into fossil fuels, including all the oil, coal and natural gas we burn today.
Ancient Egyptian, Chinese, Greek, and Native American cultures oriented their buildings and homes to maximize the collection of passive solar energy to keep them warm and to light the interior. Sunlight can start fires, melt snow and ice, heat fluids, cook our food, tell us the time of day and provide directions. (It rises in the east, sets in the west.) Lightning storms are an indirect result of heating of the earth’s atmosphere by the sun.
In 1839, a 19-year-old French physicist Edmond Becquerel, working in his father’s laboratory, invented the first “solar cell” and discovered the photovoltaic (PV) effect, when sunlight shining on his invention produced an electrical current. Becquerel went on to discover other electrical effects and photographic processes, but his solar cell never “saw much light” as it was impractical outside of a chemistry lab. It took Albert Einstein in 1905 to fully explain how and why it works, for which he was awarded the 1921 Nobel Prize. It wasn’t until 1954 that Bell Laboratories publicly revealed the first practical solar cell, built using a silicon semiconductor and with no moving parts. So began the modern solar industry. Solar PV now commonly powers our road signs, our homes, businesses, community centers, and even the Pocono Raceway. As of 2017, solar provides less than 0.5% of Pennsylvania’s electricity supply, but is increasing rapidly with significantly lower costs.
Sign Up for Our Newsletter!