Why We’re at a Crucial Point in the 6000-Year Story of Solar Energy

by Anna Gretz
November 29, 2015

Though solar energy is growing both as a buzzword and a natural resource, it’s not a twentieth-century phenomenon.

In the past few years, solar energy technology has skyrocketed. Solar photovoltaic panels are popping up everywhere around the world, and awareness and education of solar energy as an important power source is reaching new, unprecedented levels. It’s clear that we have reached a climactic point in the solar energy narrative, with news that the price of solar energy will be competitive with fossil fuel costs within years.

Though solar energy is growing both as a buzzword and a natural resource, it’s not a twentieth-century phenomenon. In fact, the roots of solar energy can be traced back over six thousand years. John Perlin’s new book, Let it Shine: The 6000-Year Story of Solar Energy lets us in on the rich and fascinating history of humanity’s use of the sun as a source of power. In a world that is reaching a major turning point in the way we generate and use energy, learning about the history of solar energy can help educate and direct the future of the solar energy growth.

How We Could Use Stone-Aged Solar

Societies around the world have been taking advantage of the sun’s energy for millennia. Perlin reveals that the stone-aged Chinese built their homes with the sun in mind, making sure they made the best use of the sun’s heat during the cold winter months. Similarly, Greek cities 2500 years ago were built to be heated by the sun, and the ancient Romans even wrote instructional manuals to teach people how to use the sun instead of turning to firewood for fuel, a source that was diminishing fast.

Let it Shine lets us in on Socrates’ basic but impressive plans for designing a solar house. 2,300 years ago, Socrates created an architectural design that would allow the heat of the sun to penetrate the home in the winter, heating its rooms during the day. The roof of the house was built with just a single slant, opening up the home to the rays of the sun as it traveled accross the sky during the day. This same design blocked the path of the sun in the summer, providing shade from the excessive heat. Socrates took advantage of the sun’s lower arc in the winter, and created a passive solar building design that would manipulate the sun’s energy and position in the sky to heat the house. Without the use of active solar technology, such as solar panels, and even in the absence of energy storage, like home batteries, Socrates found a way to capture and temporarily store the energy of the sun and use it to heat a house.

Why would we leave such great, logical architecture behind? Well we haven’t, at least not completely. Some architects continue to use passive solar building design to collect and store solar energy (in the form of heat) in the winter, and reject as much as heat as possible in the summer. These designs don’t use any “active” solar systems, like solar panels, but use their very structure to capture the heat of the sun. This completely natural way to utilize a completely free energy source has been utilized successfully long before solar panels and energy storage were conceived.

Passive solar design can also be used to naturally provide light with well-placed windows and skylights. When installed in key areas where the sun’s rays are most likely to reach, windows and skylights can provide more than enough light for an entire home. These windows and skylights can also be used in conjunction with reflective surfaces, such as mirrors or reflective metals, to maximize and re-direct the light entering into the structure. These two simple, natural methods can make the use of lightbulbs completely unnecessary except for the instance of complete darkness.

With more and more education surrounding solar energy and energy storage, as well as the publication of John Perlin’s book, we’re sure to see more integration of passive solar architecture into building plans. Many existing structures have the potential to make use of these great ways to capture and store energy from the sun, so retro-fitting existing structures may also be advantageous, and a great investment over time. The Passive House Institute in Germany has fueled momentum in Europe to build houses that utilize both traditional passive solar design. The institute is also researching new ideas of how to minimize energy use and up insulation levels to retain and reject as much heat as possible, depending on the season. The European Passive House Standard has spearheaded the development of a periodically updated planning package to provide criteria for houses seeking to utilize passive solar technologies when drawing up building plans. Both residential building value will rise and become more attractive to buyers when given a certification that they have met the European Passive House Standard. Hopefully, other nations around the world will encourage new buildings to meet similar standards.

Diminishing Resources Call for Renewable Energy Sources (And Have for a Long Time)

We already talked about the ancient Romans’ publications urging citizens to lay off the firewood, and start using the sun. They’re not the only ones who have turned to solar energy in the wake of diminishing resources. Perlin tells us about the first solar-run steam engines that began to appear in Europe, hoping to secure the transportation industry should they ever run low on fossil fuels. Similarly, as bigger cities began relying more and more on grid electricity in the late 1800’s, brand-new photovoltaic technology started showing up on the rooftops of New York City. Later, the oil crisis of 1973 motivated people to refocus on solar energy to replace fossil fuels, seeing the development of solar technologies like plastic solar pool heaters.

And the pattern of solar energy growth as a response to diminishing resources continues. Many are predicting that oil will run out in close to 50 years, followed by coal 50 years after that. This news has roused a new urgency in the need to seek renewable energy sources, like solar energy. With the solar photovoltaic industry on the rise, prices of installing solar panels are falling, with the demand for new solar installations growing daily. Solar panels, in conjunction with energy storage systems like home batteries, provide security and independence from a vulnerable electrical grid, providing one simple way that households can break free from dependence on fossil fuels. Forward-thinking architects may see the dwindling of fossil fuels as motivation to begin building homes with solar panels and energy storage systems included in each home, just as passive solar structure became a standard thousands of years ago.

The growth of new solar energy and energy storage technologies are welcome and encouraging, but combining these new options with the older technologies laid out in John Perlin’s book could project us into an even better, more energy-secure future. Imagine new homes built with Socrates’ passive solar energy architecture, taking in and storing heat directly from the sun when it’s needed, with solar panels and energy storage available for the new, modern devices we love (that Socrates couldn’t have even imagined.) With the combination of old and new ways to to capture and use solar energy, the future looks bright.

Let It Shine lays out the development of solar technology step by step, giving us a deeper understanding of how our use of the sun’s energy has developed and emerged over time. And though the scope of our electrical use has grown exponentially in the past century, the power of the sun and the human need for heat have remained unchanged. As we look for ways to use solar energy going forward, let’s not ignore the logical, and still viable, ways that humanity has harnessed the sun throughout history. With John Perlin’s new book, it’s easier than ever to learn from the past, as we forge ahead into the future.