I don't remember the exact details, it's possible that he charged it over the weeked (or just didn't use it, thus getting 2 extra day of charge).
You can play around with assumptions, like what if it was driven in stop-and-go traffic at very low speeds? Then your quoted 270Wh figure might be lower.
But anyways, with these general conditions, with the numbers you quoted, and with a 10 kwh battery (aspull), you'd be looking at a net loss of 775Wh/day, which means you could go 13 days between charges.
The point I tried to make, is that solar panels on hybrids/EVs add a lot of practical value to people who can't charge at home/work, and it's not just meaningless greenwashing.
Also that 2.6kWh figure is a yearly average probably, sunlight varies greatly over the year.