Already a subscriber?Aphotovoltaic cell is a very simple thing: a square piece of silicon typically 182 millimetres on each side and about a fifth of a millimetre thick, with thin wires on the front and an electrical contact on the back. Shine light on it, and an electric potential – a voltage – will build up across the silicon: hence “photovoltaic”, or PV. Run a circuit between the front and the back, and in direct sunlight that potential can provide about seven watts of electric power.
Throughout 2023, the world’s solar cells, their panels currently covering less than 10,000 square kilometres, produced about 1600 terawatt-hours of energy . That represented about 6 per cent of the electricity generated worldwide, and just over 1 per cent of the world’s primary-energy use. That last figure sounds fairly marginal, though rather less so when you consider that fossil fuels, which provide most of the world’s primary energy are much less efficient.
Installed capacity is doubling every three years. According to the International Solar Energy Society, solar power is on track to generate more electricity than all the world’s nuclear power plants in 2026, than its wind turbines in 2027, than its dams in 2028, its gas-fired power plants in 2030 and its coal-fired ones in 2032.
Since the 1960s, what analysts call the levelised cost of solar energy – the break-even price a project needs to get paid in order to recoup its financing for a fixed rate of return – has dropped by a factor of more than 1000, and the trend is continuing. Now that solar energy is a significant part of the world’s entire energy portfolio, the world as a whole is going to go on seeing the energy used in many applications getting cheaper and cheaper.
China quickly took the lead, and kept it. In 2023, Chinese firms made 93 per cent of all the world’s polysilicon destined for solar cells. Some are vertically integrated and make photovoltaics themselves . Some leave the diamond-saw slicing of their ingots into wafers, the precise polishing of their surfaces and the perfectly calibrated “doping” that makes the silicon into a semiconductor to their customers.
Chinese firms have other advantages, notably a vast and protected domestic market and low-cost energy. GCL-Poly and other Chinese firms have several factories in Xinjiang near huge coal-fired power plants which themselves sit more or less on top of large coal mines. Electricity accounts for 40 per cent of the cost of polysilicon production, and burning coal that was mined next door in a depreciated plant that delivers power to your arc furnaces directly is pretty cheap.
The green members of the German coalition which kicked off the huge demand-establishing subsidies of the early 2000s liked the decentralisation they offered; the Social Democrats liked the prospect of developing a new manufacturing industry devoted to their production. Both sides also saw solar panels as weapons in the fight to decarbonise the economy – but not necessarily as particularly powerful ones.
SunTrain proposes to put heavy but cheap batteries built into goods wagons that could deliver 3 gigawatt-hours to users: enough power for 725,000 homes for three days. By providing an investment case for new solar in markets that are already seeing zero prices, batteries increase demand for panels. Take California. It first saw sunshine-driven negative prices on the grid in 2017, when it had about 19 gigawatts of solar installed. It has more than doubled its solar capacity since then in part because it now has 10 gigawatts of battery storage; there have been evenings recently when batteries have been the largest source of power on its grid.
For those who are unconvinced by such an apparently outlandish way of profiting from cheap power,there is a much more tried and tested avenue. It is one of the ironies of solar power that much of its growth has been driven by relatively unsunny countries, notably those of northern Europe, where there has been little demand for additional energy. The global south has a lot of empty land, better access to sunshine and much more unmet demand.
As in India, so in many other middle-income countries. In the absence of strong policies aimed at curbing carbon-dioxide emissions, solar power may add to overall capacity as much, or more than, it displaces existing plants. And in the absence of strong policy the existing or potential capacity which it displaces will often be that which is clean, or cleaner, and comparatively expensive, not cheap and dirty coal.
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