You may have heard that enough sunlight strikes the earth continuously to offset humanity’s energy needs by a factor of 10,000—that’s according to the U.S. Department of Energy. And ever since Bell Laboratories developed the first silicon solar cell in 1954, we have striven to produce more of our electricity from the sun. But despite efforts to generate power from the earth’s largest energy source, photovoltaics still account for less than 2% of the world’s electricity, according to the Center for Climate and Energy Solutions. The obstacles to increasing the adaptation of solar energy remain its high initial costs and low efficiency—or the cost-to-efficiency ratio. While sunlight is free, the U.S. Department of Consumer Affairs calculates the average price of a residential rooftop solar installation at $12,000, after deducting federal tax incentives. For many households, this sum remains prohibitive. One solution is to approach solar with baby steps.
Sam Rashkin, former chief architect for the Department of Energy’s Building Technologies Office and director of the EPA’s Eergy Star for Homes program, introduced the Zero Energy Ready Homes concept while at DOE. Sam’s idea was a home built to the highest performance standards so that a future solar installation could easily meet its energy demands. But if sunlight produces no carbon and comes without cost, why would a home require the highest level of energy efficiency? Because intrinsic limits to solar efficiency mean there’s little room for further improvement in terms of panel technology, so other avenues toward efficiency have to be explored, explained Dr. Eikenberry.
Why is solar energy efficiency limited?
During an hour-long interview, Dr. Eikenberry painstakingly walked me through the science of transforming photons into useful voltage. The process is based on the photoelectric effect, a mechanism Albert Einstein figured…
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