Installation and maintenance of photovoltaic/solar thermal hybrid installations; Installation and maintenance of solar energy based power plants; Installation and maintenance of solar thermal installations; Repair and installation services, namely, the installation of heating, cooling and environmental control systems primarily using solar energy, renewable energy resources and rainwater; Air conditioning contractor services; Air duct cleaning services; Installation and repair of air conditioning apparatus; Installation, repair and maintenance of condensing apparatus, steam condensers, radiators for motors and engines, air reheaters, boiler tubes; Heating contractor services; Heating equipment installation and repair; Maintenance and repair of heating installations; Installation, repair and maintenance of heating equipment