CEDAR FALLS — Cedar Falls Utilities is constructing a garden of solar panels on the western side of the city as part of a project for its customers. More than 1,200 electric customers, about 6 percent of the company’s customer base, are participating in the Simple Solar project in which customers can purchase solar “shares” at $399 each. The price ended up dropping to $270 a share due to a large customer response. About a fourth of the customers are increasing the number of units they want.