How many solar panels do we need to save the climate?

How many solar panels do we need to save the climate?

A zero-carbon energy system would rely largely on low-cost solar electricity, experts say. Some 100 giant solar panel factories must be built by 2025 in order for the world to "defossilise" its energy supply by 2035.

"We know the world needs to defossilise its energy systems," said Christian Breyer, professor of solar economics at LUT University in Lappeenranta, Finland, whose research group models transition paths for future zero-emission energy systems. "We need to get to net zero greenhouse gas emissions as quickly, safely and cheaply as possible," he told DW. "To do this, we need to provide technically feasible, cost-optimized transition paths for every region of the world. Our calculations show how we can do this".

Published in 2019, LUT's cost-optimized model shows how a net-zero carbon-emitting global energy system can be achieved. In the model, solar photovoltaics (PV) -- solar panels -- provide 69 percent of total global primary energy demand for all purposes in the year that zero emissions are achieved. The rest comes from wind power, biomass and waste, hydropower and geothermal power.

His zero-emissions package does not include nuclear power because it is "simply too expensive," Breyer stressed. "Photovoltaic technology is getting cheaper every year; on the other hand, the construction costs of nuclear power plants are constantly rising." In addition, it is much easier, faster and less risky to install and operate solar power plants.

By when will the world have to stop burning fossil fuels?

The LUT researchers' solar-based model raises two questions.

First, when must the world reach net emissions of greenhouse gases if we are to meet the internationally agreed goal of keeping global warming below 1.5 degrees Celsius (2.7 degrees Fahrenheit)?

Second, how many solar panel manufacturing plants must be built -- and when -- to meet solar PV's two-thirds share of all energy production if this climate goal is to be met?

DW asked Piers Forster, a climate scientist at the University of Leeds in the United Kingdom, how much more CO2 could cumulatively be pumped into the air if it were to comply with the 1.5C target limit—without later having to do it on a large scale through expensive geoengineering or carbon-reduction measures Remove carbon dioxide from the air.

His answer is sobering. To have a two-thirds chance of staying below 1.5°C by early 2021, humanity could release up to an additional 195 gigatonnes of carbon dioxide (GtCO2) into the air, exceeding the 1,700 gigatons of carbon dioxide (GtCO2) already released since the beginning of the industrial revolution (see Constraint - EU report p. 23).

In 2019 alone, emissions totaled around 40 GtCO2. If emissions remain roughly flat over the next few years - which is quite possible - the remaining CO2 budget will be spent by the end of 2025. After that, the world will be in carbon overshoot and headed towards very dangerous climate change.

what does that mean? "We have to get to zero emissions as soon as possible after 2025," Breyer said. "The current political target year for zero emissions is 2050. It's too late."

The solution. Immediately build 100 giant photovoltaic factories

The LUT model estimates that a thriving carbon-neutral global civilization with net-zero emissions would be 90% powered by electricity – partly direct and partly via synthetic fuels (e-fuels).

And 69% of the electricity will come from solar photovoltaics. How many gigantic PV module factories will be needed to realize this future -- and when will they have to be built?

It depends on how far we are willing to overshoot the world's remaining 200GtCO2 carbon budget. Let's imagine a transition to a global system powered entirely by renewables by 2035, and let's assume new PV module factories will be in place by 2025, so they can do the job in 10 years.

The largest photovoltaic module factory in the world to date is currently under construction in Anhui Province, China. It will have an annual production capacity of 60 GW, according to its developer GCL System Integration. For comparison, global PV capacity in 2020 is about 200GW, most of which is in China.

The LUT model envisions a global installed capacity of 78,000 GW of renewable energy generation when the world reaches net-zero carbon emissions. This includes 63,400 GW of solar PV, of which around 8,800 GW will be in Europe.

Required photovoltaic gigawatt plant

By 2024, will we have built enough factories to produce the required number of solar panels in 2035? Still a long way to go. According to current industry plans, only 400 GW of annual PV production capacity will be in place by 2024, and only about 1,500 GW of solar PV modules have already been produced and installed around the world. To achieve zero emissions by 2035, when two-thirds of the world's energy is produced by solar energy, an additional 62,000 GW of photovoltaic modules (62 MW) must be produced and installed between 2025 and 2035. This means 6,200 GW per year from 2025 to 2035.

This means that, to do justice to the climate challenge, we need to build 15 times more productive capacity than currently planned by 2024. In other words, we need to build another 100 gigawatt factories of the same scale as Anhui's 60GW photovoltaic module factory before 2024, with a total annual production capacity of 6,000GW. If Europe is to produce its own PV modules instead of importing them, 15 of the 100 giant factories must be located in Europe.

This is very much in line with what Elon Musk said in 2016, when he said that with around 100 photovoltaic Gigafactories, enough solar modules could be produced to power the world for all purposes.