Performance Ration VS Total System Loss

Hello,
I start using SAM for sizing PV system with PVWatts, and in the System Design inputs I've put total system loss as 19%, after running simulation, in the result page I can't find the PR (Performance Ration) value of the system! is it assumed that the PR is the total loss ? i.e 81%=100%-19% ? if yes is it relevant as per IEC definition of the PR ?

Regards,

Hi,

PVWatts does not report the performance ratio, but you should be able to use the other outputs of the model to calculate it yourself.

The "total system losses" input accounts for losses that are not calculated by the model. PVWatts calculates losses such as those caused as light passes through the module cover and the conversion of light to DC power. For details see the PVWatts reference manual, available from this page under "PVWatts:" sam.nrel.gov/photovoltaic/pv-sub-page-2.html .

Best regards,
Paul.