Aurora supports PVWatts (versions 4 and 5) as one of its simulation engines.
When you simulate a system using PVWatts, Aurora will group your modules per mounting plane (so that each group shares a tilt and an azimuth), make a separate request for each one of the groups, and aggregate the results to calculate the total system output.
Aurora will apply system losses specified in the simulation settings. If an inverter is placed, that inverter's efficiency (the smallest of the Max. Efficiency, CEC Efficiency, and European Efficiency) will be used. If no inverter is placed, the specified inverter efficiency is used.
You can choose to run PVWatts with Aurora's shading engine rather than specify an annual or monthly shade loss. To do so, check the Shading Engine box in the Simulation Settings. If the shading engine is enabled (which it is by default), Aurora will compute an average hourly shade loss for each array in the design (where an array is a group of modules with the same tilt and azimuth). Because PVWatts does not support an hourly shade loss as an input, the shade loss is applied to the output AC power returned by PVWatts. Note that this implies the shading has a linear effect on the energy production, which is generally not the case. Aurora's simulation engine handles shade in a more robust way, using the incident irradiance on each module to adjust each module's electrical characteristics.
The simulation log for PVWatts will indicate the following information:
- Which version of the PVWatts API was used
- Whether or not Aurora's shading engine was enabled in the simulation
- The weather data set (e.g. TMY3) and weather station location
- How many arrays (groups of panels with the same tilt/azimuth) were in the design
- The number of panels, tilt, azimuth, system size, inverter efficiency, DC-to-AC ratio, module type, mounting system type, and annual AC output power for each array