September 13, 2019


Can solar power shake up the energy market? (Tim Harford, 11 September 2019, BBC)

[I]t wasn't until 1954 that scientists 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 also 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 multimillion-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 (£81) a watt - but that still meant $10,000 for enough panels to power a light bulb. Yet the cost kept dropping.

By 2016 it was 50 cents a watt and still falling fast. After millennia of slow progress, things have accelerated very suddenly.

Perhaps we should have seen this acceleration coming.

In the 1930s, an American aeronautical engineer named TP 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 is steep, but it always seems to be there.

In the case of PV cells, it's quite steep: for every doubling of output, cost falls by over 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. [...]

[N]ow that solar PV has marched along the learning curve, it is competitive even in rich, well-connected areas.

As early as 2012, PV 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 $150m (£122m) as a severance fee.

Posted by at September 13, 2019 12:26 PM