Radiated electromagnetic emissions of photovoltaic systems causing interference with radiocommunication can pose a major barrier to further photovoltaic penetration. This is particularly critical close to sensitive infrastructures such as hospitals, airports, and communication facilities. To understand the impact of each component and installation detail, we performed systematic emission measurements on comparable commercial photovoltaic systems in the range 150 kHz to 30 MHz. Our measurements indicate that systems with module optimizers are the main cause of increased emissions. The choice of a specific module type can increase emissions from inverter systems with module optimizers, while changes in cable management and earthing do not substantially affect emissions. For the module optimizer measurements, emissions were significantly increased when replacing aluminum framed half-cut modules with frameless bifacial glass-glass modules.