Tuesday, September 9th, 2014 by Scott Siegal
Solar roofing is an alternative roofing option that can not only lower your mains energy consumption but also provide sustainable exterior protection from the elements. It comes as no surprise, therefore, that it has crept into mainstream territory in the U.S. over the past decade. And it’s only bound to get bigger.
But while the average Joe has a good general awareness of its many advantages, few have so much as a passing knowledge of the way solar roofing works, how it was developed, and the different components that make up a solar roof. That’s what we’re here to discuss.
Solar Power: A Brief History
Solar roofing is a type of roofing that makes use of photovoltaic cells (also known as PV cells or solar cells), small electrical devices that generate electricity when exposed to light.
While PV cells weren’t discovered until the 1800s, solar power itself dates as far back as the 7th century B.C. Written and archaeological evidence of the Greeks, Romans, and the early Chinese using objects like mirrors, magnifying lenses, and even bronze shields to light fires have been found.
Solar technology remained rudimentary, however, until 1767, when Swiss physicist Horace-Bénédict de Saussure built the first successful solar oven. Robert Stirling, a Scottish clergyman, stepped it up a bit when he patented the first regenerative heat exchanger (which he called the ‘Heat Economiser’) in 1816. Stirling’s heat engine paved the way for the dish/Stirling system, which uses concentrated thermal energy from the sun to produce power. Next came French physicist Edmond Becquerel, who discovered the photovoltaic effect and built the world’s first PV cell in 1839.
While these were the first tentative steps towards practical solar power, several other significant scientific milestones have been made since, leading up to today’s solar panels and shingles.
Solar Panels vs. Solar Shingles
Modern solar panels are made up of layers of silicon semiconductors hooked up in series or parallel to non-magnetic conductors. Although it’s true that stronger sunshine produces more electricity, solar panels do not require direct sunlight to generate power, which is measured in kilowatts peak (kWp).
Solar shingles, on the other hand, are thin film solar cells similar in size, flexibility, and general aesthetics to conventional asphalt shingles. They have a dark purplish-blue color and usually measure 12 x 86 inches, with 5 x 86 inches of exposed surface once installed.
Solar panels generally have a much higher conversion efficiency than solar shingles: 20.3% versus the latter’s 10%. But breakthroughs in copper indium gallium diselenide (CIGS) technology have made it possible for solar shingles to reach a comparable conversion efficiency of 19.9%.
That wraps up our introduction to solar roofs. In Part Two of this blog series, we’ll take a look at the reasons why you should consider switching to solar.