the invention relates to improved techniques for manufacturing power conditioning units for use with photovoltaic modules , and to inverters manufactured by these techniques . we describe a solar photovoltaic inverter , comprising : a power conditioning circuit mounted on a circuit board , the power conditioning circuit having a dc power input to receive dc power from one or more photovoltaic panels and an ac power output to deliver ac power to an ac mains power supply ; an electrically conductive shield enclosing said circuit board ; and a plastic overmould over said conductive shield and said circuit board ; wherein said electrically conductive shield has one or more holes to allow said plastic overmould to extend through said shield to cover said circuit board .