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| Fig. 1: Solar Rooftops in Nazareth, Israel. (Source: Wikimedia Commons) |
The first solar arrays appeared in 1884 when experimentalist Charles Fritts installed a thin layer of selenium on a metal plate atop his New York City apartment, producing a current of electricity. Although he was unable to transfer this electrical current to light his building, this pioneering photoelectric module established the idea that solar energy could grow to compete with traditional energy sources and inspired the concept of rooftop solar panels. [1]
Today, solar energy is in fact in many cases replacing electricity generated from coal and natural gas, as well as kerosene lamps and diesel generators in areas lacking access to centralized power grids. Rooftop solar photovoltaic (PV) panels are currently made of thin wafers of silicon Crystal, as seen in figure 1. As photons strike these PV panels, they knock electrons loose, generating an electrical circuit. These panels require no fuel; the subatomic particles are the only moving parts in the panel and the energy they produce is entirely clean. [1] The only carbon costs of these panels come from the production of the panels, and still the solar industry is carbon negativing, having prevented more carbon emissions than it created, and creating more energy than it required. [2]
Solar is the worlds most abundant energy source, continuously striking the earth with inexhaustible energy. This offers a great alternative as the world grapples with dwindling fossil fuel resources. As global energy consumption continues to rise, increasing by an estimated 53% between 2008 and 2035, solar energy offers a clean and virtually unlimited alternative to current electricity generation. [3]
Today, solar photovoltaics overall provide less than 2 percent of the worlds electricity. However, the past decade as seen significant growth in the solar industry, especially among rooftop solar panels. In 2015, approximately 30% of all distributed solar panel systems were small-scale panels delivering less than 100 kilowatts of power. Germany alone holds 1.5 million of these systems, and in Bangladesh, with a population of 157, over 3.6 million homes have their own solar systems installed. [1]
Worldwide, these rooftop panels are becoming increasingly accessible as costs fall due to advances in panel technology, economies of scale in manufacturing, and social and political incentives for installation. Furthermore, creative end-user financing models such as third party ownership arrangements and loan systems make solar rooftops accessible across the globe and for those who cant pay the upfront costs without immediate returns. However, soft costs of installation and acquisition have not seen the same rapid decline as the hard costs of the panels themselves.
Affordability is not the only reason for installing rooftop solar; PV panels generate electricity without emitting any greenhouse gasses, and by producing energy at the site of consumption, rooftop panels avoid losses inevitable in the transmission of power from a centralized grid to the consumer. Furthermore, when placed on a grid-connected roof, they produce energy at the site of consumption they can help utilities meet broader demand by feeding unused energy into the grid, especially in summer. [1] Not only good for the utility companies, this net metering arrangement allows owners to offset any electricity they buy when the sun isnt out, making solar rooftops even more financially feasible.
Off the grid, in developing societies without centralized electrical systems, rooftop solar brings electricity to those who otherwise dont have access. On Lake Titicaca, the Uru People have bypassed the construction of a centralized power grid and have turned to rooftop solar to replace kerosene use. Not only clean and sustainable, solar power aligns well with the Uros culture as the Uru People believe themselves to be Lupihaques, or Sons of the Sun.
Considering this growth in the solar industry, Drawdown climate scientists believe that solar rooftops can have a major impact on reducing CO2 emissions. Given that solar generated on rooftop panels accounts for just .4 percent of total global electricity generation at present, and market trends suggest that this figure will reach 7% by 2050, that growth can reduce global carbon emissions by 24.6 gigatons. Similarly, if rooftop solar implementation drops to $627 per kilowatt by 2050 as estimated, rooftop installation of PV panels can save $3.4 trillion in home energy costs in the next 32 years, making increased installation of solar rooftops not only environmentally sustainable, but economical too. [1]
© Tule Horton. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] P. Hawken, Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming (Penguin Books, 2017).
[2] A. Louwen et al., "Re-assesment of Net Energy Production and Greenhouse Gas Emissions Avoidance After 40 Years of Photovoltaics Development," Nat. Commun. 7, 13728 (2016).
[3] "Led by Demand in China, Energy Use is Projected to Rise 53% by 2035," New York Times, 19 Sep 11.
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