Spring Equinox – A History of Solar
Solar Technology – It’s older than you think!
Solar energy was harnessed by humanity long before history was recorded. This started with the intentional use of fire – a release of temporarily stored solar energy used to light up the darkness and cook hunted and foraged food. Agriculture is just the intentional diversion of solar radiation into food. Plant cells can transform sunlight directly into usable energy, which in turn provides energy for us in the form of food. Although ancient civilizations probably did not understand the biological mechanics of these energy transformations, it’s clear that our species has long understood the importance of the sun.
From Stonehenge to Tikal to the ancient Chinese dynasties, we see evidence that past societies designed structures around the sun’s position in the sky. Calendars were built around solstices and equinoxes. While we don’t know if Archimedes truly lit enemy ships on fire by reflecting the sun with mirrors, crude lenses have been used to create fire for practical and ritual purposes since 7th century BC. Greenhouses made of thin, transparent stone were used by the Romans to grow exotic and out of season crops. Sunrooms were built into housing in China starting around 6000 BC. Stonehenge and the temples of Tikal were built to celebrate solstices and equinoxes and mark the passage of time and seasons.
Tracking the movement of the sun also led to advances in math and natural sciences – but technological and scientific advances don’t always occur in a linear fashion. Copernicus’ heliocentric (sun-centered) theory of the cosmos was famously regarded as heresy, but heliocentric models were treated as fact by many Greek and Roman scholars. Galileo’s telescopes provided evidence for this theory, despite his prosecution for the proposal. Sir Isaac Newton was also fascinated by the sun. He split sunlight by shining it through prisms and temporarily blinded himself in pursuit of understanding the nature of sunlight (you can thank his fascination for that calculus class you still dream you forgot about). Meanwhile, indigenous people in the Americas had been building homes with south-facing windows for centuries, using the position of the sun as a natural source of heating in the winter.
The age of industrialization brought us many of the technological advances we depend upon today, and the acceleration of energy technology began. Edison’s and Tesla’s experiments with electricity gave people power in their own homes. The internal combustion engine made us more mobile than we had every been, and we began using sunlight in the form of fossil fuels to propel us around the world. It wasn’t without cost. The burning of fossil fuels since 1850 has resulted in more carbon dioxide and other greenhouse gasses into the atmosphere than at any point in the past 800,000 years. This all happened so quickly, yet we find it hard to imagine breaking our dependence on them.
There are alternatives to fossil fuels. The photovoltaic effect (electric current generation from sunlight) was discovered in 1839. In the 1880s the first solar cell was created, although it would not be efficient enough for practical use – that would have to wait until the 1950s. By the 1970s, solar panels were in use on every continent. We have seen vast improvements in the technology since, as they are now so efficient that many modern households can offset their annual usage using just the space they have available on their roofs. Despite these leaps in technology, it wasn’t until very recently that individuals and governments alike have started to look at solar as a true alternative to coal and gas. Enough sunlight hits the surface of the Earth each hour to power the entire world for a year, and technology to capture and convert it constantly improves.
Many people are caught between a sense of urgency and the sense that the technology just isn’t there yet – but how many people are holding off on getting a smartphone because the technology isn’t “finished”? We hope advances in solar continue to happen and get better. Scientific and technological innovation is in our DNA, so it is unlikely we will reach a point where we have decided that solar technology is “good enough.” Advancements in technology also don’t always render old technology obsolete – after all, we’re still using greenhouses, sitting around fires, and observing the change of seasons based on the position of the sun relative to Earth. We don’t know how solar will look in the future, but we don’t have to wait to find out to be a part of solar history.