John Browne had spent the day at a solar glass panel factory outside Shanghai, making the case for Kastus, a water-based solution that makes solar panels more efficient. China dominates the global solar panel market and eight out of the world’s top 10 producers are based in a couple of provinces in the southeast of the country. “We were down here six months ago and the reception, I would say, was lukewarm,” he says. “Six months later, it’s very warm. “The scale of these things is incredible. The factory is a kilometre long but there were only 20 people working…