Wikipedia says Europe uses mainly the shorter cab-over-engine tractors in order to maximize trailer length while staying under the total length limit. They commonly pull standard ISO shipping containers, so in that case at least the difference is all in the tractor.
The storage capacity is sized for daily consumption, not the yearly figure you quoted. And of course, this is one small project out of the hundreds of plants that will be needed to meet climate goals.
The biggest issue with solar right now is that the output varies over the course of the day, leaving other power plants to take up the load at night or during cloudy weather. The attached battery storage averages out the solar plant’s output, letting it be a useful contributor to the grid around the clock. There’s other benefits like grid stabilization and peak shaving, where the battery stores and releases oversupply from the rest of the grid, not just the attached solar panels.
I’m running it on a DS918+ right now. I copied-pasted their docker-compose file and had it up in half an hour or so.