Solar power is brilliant. It just keeps getting cheaper and more efficient all the time. And it’s quick and easy to install and integrate into existing power networks. Mostly. But the best thing about solar is its ability to scale.

You can use a portable solar panel to charge your phone. Or combine it with a small power station and you can run your fridge while camping. You can cover your roof with panels and run your whole house on solar, even charge your car. And businesses, factories, malls can all contribute space to harness ‘free’ energy from the sun.

China is the poster child for large scale solar plants. In the last seven years they’ve added over 1,000GW of solar capacity. They’ve got robots that install a panel every 40 seconds and drones to keep them clean. That’s enormous scale and difficult to match anywhere else, as the panels are all made in China too.

But that’s where the promise fails. We were told that solar was going to replace fossil fuels and nuclear. Turns out China has increased both, because you can’t run the world’s biggest manufacturing economy on solar alone, not even with batteries.

And don’t even think of trying it in Scotland. Twice your solar capacity in batteries won’t do much in two weeks of continuous rain. Spain also found out the hard way a few years ago, that if you run your grid on 78% solar without enough inertia in the system, one small trip can bring the whole thing down, countrywide.

Don’t get me wrong, solar is the future, especially for households, most businesses, and micro-grids. But for real utility scale reliability and cost efficiency, you need enough traditional baseload to back it up, and keep it honest.