See here for current incentives.
Pacific Power and Portland General Electric currently offer up to $4,400 dollars for residential installations and up to $50,000 for commercial solar projects. These incentives are based on an allocated funds that decreases periodically.
Your business may be able to recover investments in solar systems through rapid depreciation (5 year) deductions on federal tax returns. 2018 change in Federal tax law allow for an additional 100% bonus depreciation over one year.
Businesses in rural areas may qualify for USDA Rural Energy Grants that can provide 25% of the cost up to $20,000.
Like the Federal MACRS above, you may be able to take a rapid 5 year depreciation on state tax returns.
Green Tags are certificates that represent the environmental benefits from a specific amount of electricity from solar panels (or other renewable sources); their value is market driven.