Fixed-tilt solar arrays constructed from screw anchors. In some cases, purlins are attached directly to truss legs. In others, they are attached to truss caps joining the free end of each truss leg. In still further ones, screw anchors are driven in rows and interconnected by a pair of hinged members, one of which provides a mounting plane for solar panels. Each screw anchor may serve as a connection point for the trailing hinged member of the first foundation and the leading hinged member of the next foundation. In still further cases, a hinged truss cap may be used to accommodate different tilt angles with the same foundation.