A city has identified two options for developing solar power capacity. The investment basis for comparison is 8 years, with interest fixed at 12% per year.

Option A is to build a photovoltaic array at 50% capacity now, at a cost of $1 million, with an operating cost of $200,000 at the end of each year for 4 years. At the end of year 4, the array will be expanded to 100% capacity, at a cost of $900,000. After the expansion, operating costs will become $350,000 per year.

Option B is to build a full-scale solar thermal electric generation plant now at a cost of $1.5 million, with end-of-year operating costs of $250,000.

Which option should be chosen?