A vertical axis windmill system for interacting with ground level winds has a plurality of vertical windmill units. Each vertical windmill unit includes a rotation unit and outer rings. The rings are secured to the vertical support columns. The rotation unit has a plurality of blades equally spaced around a rotatable center shaft. Each blade has a plate extending from the central shaft to an outer end. The plate has a curvature from an upper edge to the lower edge. Each of the blades has a plurality of openings. A plurality of flaps are pivotably mounted to the blade to move from an open position allowing air through the plurality of openings to a closed position limiting air through the plurality of openings. The system has a generator for converting the rotation motion of the rotatable central shaft to electrical energy.