In 1965 Gordon Moore, co-founder of Intel, wrote a paper on a phenomenon he noticed in the transistor industry: the number of transistors that could fit on an integrated circuit, or microchip, doubled about every two years, leading to exponential growth in speed and power. This rule of thumb, now known as Moore’s Law, has been remarkably resilient in the decades since.
In a recent article for Greentech Media, Michael Kanellos explores the possibility that increased efficiencies in manufacturing, combined with a growing flood of research, both private and public, could generate a version of Moore’s Law for photovoltaics (solar cells).
Thin is the new Small
For solar cells, “smaller” is not actually better, since the surface area of a photovoltaic cell determines how much of the sun’s energy it absorbs. But thinner – that’s where the efficiencies start to happen.
In thin-film solar cells, the materials used to convert sunlight into electricity are literally printed onto a backing in layers as thin as a few dozen atoms. This results in fewer materials used per watt of electricity generated, which means lower costs and weight. This is especially important in the solar cell industry, where price fluctuations in silicon and other materials force up prices, and weighty solar panels are more expensive to install on rooftops.
The solar panel pictured above for instance, produced by Ascent Solar of Littleton, CO, is 16.4 feet long but weighs only 4.4 pounds and generates 123 watts of electricity. That’s a mere 176 pounds for a 5 kW array (not including cell housing and wiring), which is enough to power an average American home.
Meanwhile, efficiencies in electric generation have been steadily moving upwards. While the above solar cell rates only 9.1% efficiency (meaning it converts 9.1% of the sun’s energy into electricity), just this past week Ascent announced its cells had been government-certified at up to 10.4%. Other thin-film companies have reached efficiencies of up to 14.2% in the lab.
It is still too early in the development of thin-film cells for anyone to try and posit a specific Moore’s Law-type rule of thumb for the industry. But given the similarities between solar cells and microchips, including the materials and technologies used in manufacturing, the growing number of companies involved, and the massive potential market, it seems possible that comparable patterns of efficiency will start to emerge.
Thin-film solar cells
Another (more technical) Take on a Solar Moore’s Law