Farmland for Solar (and not biofuels)?

Opposition to solar farms on low grade farmland are misplaced

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There have been a lot of stories in the press recently claiming that solar farms are going to replace food farms, lower property prices, and so on.

For example:
The Telegraph – “Tenth of farmland to be axed for net zero” (Jan 2025)

I thought it might be a good idea to put some numbers down and see what all the fuss is about.

The UK’s energy minister, Ed Miliband, has set a target of 50 GW of solar capacity by 2030—about a threefold increase from current levels. That may sound like a lot, but Germany already has over 100 GW, and the Netherlands has 27 GW, despite being about one-third the size of England and more densely populated and farmed.

There is, of course, universal agreement that solar panels should ideally be mounted on rooftops—homes, warehouses, etc.—as they mostly are in Germany and the Netherlands. Except, that is, among the finance people. Solar panels themselves are now so cheap that installation is the main cost, and ground-mounted arrays are cheaper to install.

So how much land would 50 GW of ground-mounted solar occupy? (It won’t all be ground-mounted, but by 2040, we can be fairly sure that over 50 GW will be.) In the UK, solar farms typically have a capacity of about 50 MW per square kilometre. So 50 GW would occupy about 1,000 km².

That may sound like a lot, but according to a 2017 BBC article:

“Overall, British golf courses are calculated to cover 1,256 km²—an area roughly equivalent to Greater Manchester and, according to some estimates, just a little smaller than all the land covered by housing.”

A more relevant comparison is with land used for biofuels. According to government sources:

In 2023, 133,000 hectares of agricultural land in the UK were used to grow crops for bioenergy. This represents 2.2% of the UK’s arable land.

That’s 1,330 km², or about 30% more than would be required for 50 GW of solar PV. Yet we don’t hear many objections to this. The same page states:

In 2023, 36% of land used for bioenergy was for biofuels (biodiesel and bioethanol) used in UK road transport, with the rest mostly used for heat and power.

That’s close to 500 km², or half the land needed for 50 GW of solar. Why is this comparison interesting? Recent analysis (see here and here) suggests:

You need 40 times more land to power a car using biofuels than an electric car powered by solar.

This suggests we should replace land used for biofuels with solar PV farms, scrap biofuel blending requirements in petrol and diesel, and accelerate the switch to electric vehicles. Compared to biofuels, solar PV is better for biodiversity, consumes fewer external resources, and provides more revenue for farming communities.

Annual solar production in the UK was 15 TWh last year. So 50 GW of solar could produce around 50 TWh per year (a conservative estimate—ground-mounted arrays typically yield more than rooftop ones). Assuming an electric car uses 20 kWh per 100 km (a typical winter figure, accounting for charging losses), that’s sufficient for 250 billion passenger car kilometres.

For comparison, UK cars drove 400 billion kilometres in 2023. If all of these were electric, they’d consume 60–80 TWh of electricity—requiring around 80 GW of solar PV, or 1,500 km² of land.

What About Seasonality?

Of course, this is a hypothetical scenario—no one is suggesting we power all UK cars with solar in December. But just for the numbers:

In December 2024, the UK’s 15 GW of solar produced 0.46 TWh, compared to 2.04 TWh in July and a monthly average of 1.3 TWh. If 1/12th of annual mileage is done in December, that’s a requirement of 6.67 TWh. To meet that with solar alone, the UK would need 225 GW of solar PV, occupying about 4,000 km².

We might need those golf courses after all.

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Of course, the UK isn’t alone. According to Eurostat, both France and Germany have around 5,000 km² of land used for biofuels. They have no excuses either.