The larger end of the vertical wind turbines, the Big Star even weighs in at a hefty 3.3 tonnes. The Ropatec Big Star WindRotor is a three phase grid connected Vertical Axis Wind Turbine which can be either ground mounted on a steel mono pole or building mounted subject to a Structural Engineers report. Standard mast sizes are 5.5m, 11m and 15m, and, according to the manufacturer, the turbines expexted life is 20 - 25 years. The grease guns which lubricate the turbine's bearings will require replacement every 5 years.