Bangor city councilors have agreed to spend $8,600 to study how much it would cost the city to build and operate solar arrays on municipal properties, as well as what energy savings would come from those investments. At a meeting on Monday night, the council’s finance committee accepted an $8,600 bid from ReVision Energy Inc., a Maine-based company with offices in Portland and Liberty, to evaluate the merits of three different types of solar installation: on rooftops, on carports and on the ground. “We have a lot of land, some of it not for building,” City Manager Catherine Conlow said during the meeting.