The reference yield is the ratio of the total solar radiation Ht (kWh/m2) arriving at the PV solar panels' surface and the reference radiation quantity G0 (kW/m2). This parameter. The collection losses (LC): The collection LC losses are defined as the difference between the reference efficiency and the PV field efficiency. The PV field efficiency is defined as the ratio between the total energy EDC (kWh) generated by the PV system for a defined period (day, month,. The final yield is the total energy produced by the PV system, EAC (kWh) with respect to the nominal installed power P0(kWp). This quantity, which. The PR indicates the overall effect of losses on the energy production of the PV system. The PR values indicate how a PV system approaches.