Solar PV

Episode Summary

The podcast discusses the history and potential of solar photovoltaic (PV) technology. It explains how solar PV cells convert sunlight into electricity using the photovoltaic effect. This effect was discovered in the 1800s, but early solar cells made from selenium were inefficient and expensive. A breakthrough came in 1954 when researchers at Bell Labs created silicon solar cells, which were much more efficient. Initially, solar PV was only used to power satellites, where cost was not an issue. On Earth, it remained prohibitively expensive for widespread use, costing thousands of dollars per watt of electricity in the 1970s. However, the cost has dropped dramatically in recent decades due to the “learning curve” phenomenon. As production increases, costs fall by over 20% for every doubling of output. Since 2010, PV production has increased 100-fold, leading to today’s costs of around 50 cents per watt. This cost reduction has made solar PV competitive with fossil fuels even in developed countries. Solar farms are now being built worldwide to take advantage of cheap PV panels. Developing countries also see solar as a way to provide electricity in rural areas. Even large companies are switching to solar to reduce energy costs. While some challenges remain, the ongoing learning curve effect makes the large-scale success of solar PV highly likely in the future.

Episode Show Notes

Solar power has been harnessed by civilisations since the days of the ancient Greeks, but it's now on the verge of being more important than ever. Tim Harford examines how much of a challenge it poses to the energy establishment, and what that could mean for the planet's future.

Episode Transcript

SPEAKER_02: Amazing, fascinating stories of inventions, ideas and innovations. Yes, this is the podcast about the things that have helped to shape our lives. Podcasts from the BBC World Service are supported by advertising. SPEAKER_05: Hey, I'm Ryan Reynolds. At Mint Mobile, we like to do the opposite of what big wireless does. They charge you a lot, we charge you a little. So naturally, when they announced they'd be raising their prices due to inflation, we decided to deflate our prices due to not hating you. That's right, we're cutting the price of Mint Unlimited from $30 a month to just $15 a month. Give it a try at mintmobile.com slash switch. New activation and upfront payment SPEAKER_04: for three month plan required. Taxes and fees extra. Additional restrictions apply. See Mintmobile.com for full terms. SPEAKER_03: 50 things that made the modern economy with Tim Harford. SPEAKER_00: Socrates believed that the ideal house should be warm in the winter and cool in the summer. With clarity of thought like that, it's easy to see how the great philosopher got his reputation. At the time, such a desire was easier to state than to achieve. Yet many pre-modern civilizations designed buildings to capture sunlight from the low hanging winter sun while maximizing shade in the summer. All very elegant. But that's not the kind of solar power that will run a modern industrial economy. And millennia went by without much progress. A golden thread, a book published in 1980, celebrated clever uses of solar architecture and technology across the centuries and urged modern economies racked by the oil shocks of the 1970s to learn from the wisdom of the ancients. For example, parabolic mirrors used in China 3,000 years ago could focus the sun's rays to grill hot dogs. Solar thermal systems would use winter sun to warm air or water that could reduce heating bills. Such systems now meet about 1% of global energy demand for heating. It's better than nothing, but hardly a solar revolution. A golden thread only briefly mentions what was, in 1980, a niche technology. The solar photovoltaic, or PV, cell, which uses sunlight to generate electricity. The photovoltaic effect isn't new. It was discovered in 1839 by Edmond Becquerel, a French scientist. In 1883, Charles Fritz, an American engineer, built the first solid state photovoltaic cells and then the first rooftop solar array in New York City. These early cells, made from a costly element named selenium, were expensive and inefficient. The physicists of the day had no real idea how they worked either. That required the insight of a fellow named Albert Einstein in 1905. It wasn't until 1954 that researchers at Bell Labs in the US made a serendipitous breakthrough. By pure luck, they noticed that when silicon components were exposed to sunlight, they started generating an electric current. Unlike selenium, silicon is cheap and Bell Labs researchers reckoned it was 15 times more efficient. These new silicon PV cells were great for satellites. The American satellite Vanguard 1 was the first to use them, carrying six solar panels into orbit in 1958. The sun always shines in space and what else are you going to use to power a multi-million dollar satellite anyway? Yet, solar PV had few heavy duty applications on Earth itself. It was still far too costly. Vanguard 1's solar panels produced half a watt at a cost of countless thousands of dollars. By the mid-1970s, solar panels were down to $100 a watt, but that still meant $10,000 for enough panels to power a light bulb. Yet, the cost kept falling. By 2016, it was half a dollar a watt and still falling fast. After millennia of slow progress, things have accelerated very suddenly. Perhaps SPEAKER_00: we should have seen this acceleration coming. In the 1930s, an American aeronautical engineer named T.P. Wright carefully observed aeroplane factories at work. He published research demonstrating that the more often a particular type of aeroplane was assembled, the quicker and cheaper the next unit became. Workers would gain experience, specialised tools would be developed and ways to save time and material would be discovered. Wright reckoned that every time accumulated production doubled, unit costs would fall by 15%. He called this phenomenon the learning curve. Recently, a group of economists and mathematicians at Oxford University found convincing evidence of learning curve effects across more than 50 different products, from transistors to beer, including photovoltaic cells. Sometimes the learning curve is shallow and sometimes it's steep, but it always seems to be there. In the case of P.V. cells, it's quite steep. For every doubling of output, cost falls by more than 20%. And this matters because output is increasing so fast. Between 2010 and 2016, the world produced 100 times more solar cells than it had before 2010. Batteries, an important complement to solar P.V., are also marching along a steep learning curve. The learning curve creates a feedback loop that makes it harder to predict technological change. Popular products become cheap, cheaper products become popular, and any new product needs somehow to get through the expensive early stages. Solar P.V. cells needed to be heavily subsidised at first, as they were in Germany for environmental reasons. More recently, China seems to have been willing to manufacture large quantities in order to master the technology, leading to President Obama's US administration complaining that, rather than being too expensive, imported solar panels had become unfairly cheap. Solar panels are particularly promising in poorer countries with underdeveloped and unreliable energy grids and plenty of sunshine during the day. When the Indian Prime Minister Narendra Modi assumed office in 2014, for example, he announced ambitious plans to build large utility-scale solar farms, but also to establish tiny grids in rural villages with little or no access to the main grid. But now that solar P.V. has marched along the learning curve, it's competitive even in rich, well-connected areas. As early as 2012, P.V. projects in the sunny US states were signing deals to sell power at less than the price of electricity generated by fossil fuels. That was the sign that solar power had become a serious threat to existing fossil fuel infrastructure. Not because it's green, but because it's cheap. In late 2016 in Nevada, for example, several large casino chains switched from the state utility to purchase their power from largely renewable sources. This wasn't a corporate branding exercise. It was designed to save them money even after paying $150 million as a severance fee. The sun doesn't shine at night and winter storage remains a big challenge. As Socrates warned us, the wisest people understand that they know nothing. But the learning curve tells us that the ultimate triumph of solar P.V. seems likely. It is getting cheaper as it gets more popular and more popular as it gets cheaper. Socrates notwithstanding, that sounds like a recipe for success. SPEAKER_03: An up-to-date guide to a fast-moving area is Chris Goodall's book, The Switch. For a full list of our sources, please see BBCWorldService.com slash 50things. SPEAKER_01: It's the most popular podcast from the BBC World Service. The Global News Podcast brings you a truly global perspective on the day's events. And with correspondence located all SPEAKER_00: SPEAKER_01: over the world, the BBC can bring you local coverage of world events. SPEAKER_02: Expand your world view with the Global News Podcast. Subscribe by searching for Global SPEAKER_01: News Podcast to stay up to date.