Reference yield

Reference yield is the energy a PV system could deliver over a given period under standard conditions if it had no losses. It is written Yr. A lowercase yr is used for the instantaneous reference yield. Over a period, reference yield is given in hours. Monitoring platforms can also show it in kWh per kWp, labelled Ref_Yield. You compare reference yield with the final system yield to get the performance ratio. Expected yield for a period is the reference yield multiplied by the expected performance ratio. The irradiance input can come from module-level sensors (high accuracy, high hardware cost), cell sensors (medium accuracy, low cost) or a local comparison (medium-low accuracy, no hardware, but the baseline must be checked). If you plot array yield against reference yield and fit a straight line through the origin, the slope is roughly the average array performance ratio. A change in the weekly slope points to a sudden fault or a trend.

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• sentence 3: support check: partial - Unit h is stated and Ref_Yield in kWh/kWp is shown, but nothing says monitoring platforms show it that way over a period specifically; the Ref_Yield label is stated though. -->