The energy transition

Here is a sentence that would have sounded like science fiction twenty years ago: in many parts of the world, electricity from sunlight is now among the cheapest electricity in the history of electricity. Not the cheapest green option. The cheapest option. Understanding how that happened is the single most hopeful fact in this whole subject, because the reason it happened is still running.

The learning curve that changed everything

Solar panels follow a pattern engineers call a learning curve: every time the total amount ever produced doubles, the cost falls by a roughly constant fraction. More panels get made, factories get better, designs improve, costs drop. Lower costs mean more people buy panels, which doubles production again, which drops the cost again. It is compounding, the same engine that grows investments, except here it has been shrinking the price of energy for decades.

But why should making more of something make it cheaper, reliably, decade after decade? It is not magic and it is not luck. Every panel that comes off a line teaches the people and the machines that made it something small: a step that can be automated, a sliver of silicon that need not be wasted, a design tweak that lifts how much sunlight becomes electricity. Multiply those small lessons across hundreds of millions of panels and the cost of the next one keeps dropping. Economists call this learning by doing, and it turns up wherever a product is made in rising volumes to a repeatable design, from aircraft in the early days of aviation to televisions to solar cells today.

A rough illustrative version makes the power of it clear. Suppose a technology costs 100 dollars a unit today, and every time cumulative production doubles the price falls by 20 percent, which is a fairly typical learning rate for solar. After one doubling the unit costs 80 dollars, after the second about 64, after the third about 51, and after the fourth around 41. Four doublings, and the price has fallen by nearly 60 percent, without a single dramatic breakthrough along the way. Solar production has doubled far more than four times over recent decades, which is why the price did not merely drift down, it collapsed.

The strangest part of the story is that almost nobody official saw it coming. Year after year, the world's respected energy forecasters predicted that solar growth would soon level off. Year after year, reality blew past the forecast, and the forecasters drew a new flat line from the new higher starting point. Solar costs fell far faster and further than the official predictions said they could. When you hear that a clean technology is too expensive, remember that the experts said the same about solar, repeatedly, while it was busy becoming cheap.

Wind and batteries are on the same ride

The learning curve is not a solar quirk. Wind turbines have grown taller and more efficient while their electricity got cheaper. Batteries are riding an even steeper version of the same curve, pushed along by the electric vehicle industry, which needs them by the millions. Storage that was an exotic experiment a decade ago is now a standard line item in grid planning. Once a technology is on a learning curve, scale itself becomes the solution.

Australia's unfair advantages

Australia is arguably the best placed country on Earth for this transition. We have some of the strongest sunshine of any inhabited continent, powerful and reliable winds, and enormous space to use them. And Australians have already voted with their rooftops: roughly one in three Australian homes has solar panels, which is world leading uptake by a wide margin. On sunny days, rooftop solar alone supplies a striking share of some state grids. The shift is not a future promise here. You can watch it happening in the grid data, live, today.

That rooftop uptake also explains a peculiar new problem, and it is worth understanding because it is the shape of things to come. On a mild sunny day so much solar now floods some state grids around the middle of the day that wholesale electricity prices there can fall close to zero, or even go negative for a while, because supply outruns demand. The challenge has flipped. It used to be finding enough power for the evening peak. Increasingly it is soaking up the abundance of cheap midday power and moving it a few hours to when people cook dinner, which is precisely the job batteries and pumped hydro are built to do.

But can it actually run a grid?

A common objection deserves a straight answer. If the sun sets and the wind drops, people ask, how can it possibly run a whole country? The honest reply is that no single source runs a grid on its own, and the coal plant it replaces did not either, which is why grids have always been built from a mix of generators, backups and controls. What the new mix adds is storage and firming: batteries that soak up cheap midday solar and release it at dinner time, pumped hydro that works like a giant rechargeable battery made of water and gravity, and gas or hydro kept on standby for the rare long stretch that is both still and cloudy. The point is not that any one source is perfect. It is that a planned mix of cheap generation and storage now does the job that one dirty source used to do alone, and does it for less.

The honest hard parts

• Storage: the sun sets and the wind pauses, so cheap generation needs batteries, pumped hydro and other firming to cover nights and cloudy weeks.
• Transmission: the best sun and wind are often far from cities, and building new lines takes years and genuine consultation with the communities they cross.
• Minerals: batteries and turbines need lithium, copper and other minerals, and mining them responsibly matters.

These problems are real, and pretending otherwise would break the honesty rule of this subject. But notice what kind of problems they are: engineering, planning and fairness problems. Humans have a long record of solving exactly those, especially when the economics are pushing in the same direction.

What this looks like in your week

You do not have to wait for any of this. If your family owns the roof, panels now pay for themselves in a handful of years in most of Australia, after which the midday electricity is close to free. If you rent or live in an apartment, the same shift still reaches you through the grid: running the dishwasher, the pool pump or a phone and laptop charger in the middle of the day, when solar is flooding the system, is now often the cheapest time to use power, rather than the old habit of waiting for late at night. When you get your licence and eventually a car, an electric one charged on daytime solar is running on sunlight that fell on your own suburb that morning. None of this asks you to sacrifice. It asks you to notice when the cheap clean energy is there and use it then.

Keep the learning curve in mind for the rest of this topic, because it is the engine underneath almost every solution here. The batteries getting cheaper are the same batteries that store this solar, and the same demand from electric vehicles is what keeps pushing them down the curve. The how change happens lesson then shows the other half of the story, because cheap technology on its own is necessary but not enough: rules, public pressure and time have to line up with it before a whole system tips.