The detailed photovoltaic model calculates a grid-connected photovoltaic system's electrical output using separate module and inverter models. It requires module and inverter specifications along with information about the number of modules and inverters in the system. You can either provide your own module and inverter specifications from a manufacturer's data sheet, or choose a module and inverter from libraries. The detailed photovoltaic model estimates losses due to the effect of temperature on module performance, and has options for calculating shading and other losses in the system. The model also includes a system sizing assistant to help you determine the number of modules and inverters in the system.
Use the detailed photovoltaic model when you have detailed information about the equipment that will be used in the system.
The PVWatts model is an implementation of NREL's popular online photovoltaic calculator. It models a grid-connected photovoltaic system using a few basic inputs to describe the system's nameplate capacity, array orientation and mounting type, and system losses. PVWatts makes internal assumptions about module and inverter characteristics for three types of modules. SAM's implementation of PVWatts includes options for modeling shading that are not available with the online version.
Use the PVWatts model for preliminary project analysis before you have information about the type of equipment you plan to use in the system, or for other analyses that require a reasonable estimate of a photovoltaic system's electrical output.
Concentrating Photovoltaic (CPV)
The concentrating photovoltaic model is appropriate for grid-connected photovoltaic systems with high concentration photovoltaic modules. The concentrating photovoltaic model uses separate models to represent the module and inverter. It requires information about the design of the concentrator and efficiency of the cell at different irradiance levels. For the inverter model, you can either use specifications from a manufacturer data sheet, or choose an inverter from a library.