SALEM, Ore. — A national solar energy company is betting nearly $1 billion on an Oregon development spree, including five new solar farms in Marion and Polk counties. Cypress Creek Renewables, a developer that sells electricity to utility companies and already operates seven solar sites in Oregon, is building farms near Salem, Silverton, Gervais, Turner and Grand Ronde. Cypress Creek, which operates in 15 states, has its largest group of farms in North Carolina, where more than 100 are either operating or under construction, company officials say. The Marion and Polk county farms will cover about 12 acres each, producing enough energy to power some 450 homes.