The pre-conversion efficiency reflects the losses experienced before the beam hits the actual semiconductor material

The pre-conversion efficiency reflects the losses experienced before the beam hits the actual semiconductor material, provoked by the environment, such as shading. The system efficiency can be defined as the electrical losses provoked by cabling, transformer and inverter.
PA – Plant availability
The PA is a percentage that represent the time that the power plant is available to provide energy to the grid. It can be understood as the up-time of the station. Little downtime often occur because solar PV plants has high percentage of availability. In fact, PV stations nearly equivalent to 100% thanks to the fact that the majority of the parts are fix and maintenance can be planned at night. The plant availability factor and the capacity factor are not the same.