Business Green: Just days after a new study suggested solar panel prices will fall by more than a quarter this year, top execs at two of the world’s largest solar manufacturers have this week predicted the sector will be able to compete on price with conventional power sources within five years. Speaking as part of this week’s Reuters Global Energy Summit, Steven Chan, chief strategy officer at Suntech Power, told the news agency that he expected silicon costs per watt to halve over the next five …