Oregon officials are preparing to foreclose on SoloPower Inc. after the government-backed startup missed a loan payment this week in the latest setback for the state's reeling green-energy sector. SoloPower, which is still scrambling to revive its struggling North Portland plant, missed a $50,800 payment Wednesday on a $10 million loan from the Oregon Energy Department, an agency spokeswoman said Friday. If the San Jose, Calif., company defaults, Portland taxpayers could be out $5 million, because the city guaranteed half the loan last year in wooing the plant away from Wilsonville. Already the state of Oregon is out $20 million...