Estimation of energy losses due to partial equipment failure for photovoltaic systems from measured and modeled inputs

A method of monitoring a photovoltaic system and quantifying energy losses due to partial equipment failure, comprising:

• inputting modeled power and energy time series data for the photovoltaic system into a computer processor, wherein the modeled power and energy time series data includes a set of a timestamp, a modeled power and a modeled energy;
• receiving measured power and energy time series data for the photovoltaic system, wherein the measured power and energy time series data includes a set of actual data readings having a power and energy reading with an associated measured time series data timestamp;
• inputting the measured power and energy time series data into a computer processor;
• merging by the computer processor the modeled power and energy time series data with the measured power and energy time series data to determine and to provide a performance ratio time series;
• determining in a computer processor a normalized daily effective system capacity time series by calculating a daily maximum of the performance ratio times series with outliers removed to provide the normalized daily effective system capacity time series;
• determining in a computer processor a set of differentials between consecutive daily data points in the normalized daily effective system capacity time series;
• applying an anomaly filter to the set of differentials between consecutive daily data points in the normalized daily effective system capacity time series to identify days on which a capacity of the photovoltaic system is likely to have changed;
• partitioning the normalized daily effective system capacity time series and then calculating measures of central tendency for the resulting partitions to generate a piecewise constant time series that describes a normalized daily effective system size;
• and
• modulating the modeled power and energy time series data by an inverse of the piecewise constant time series to provide an estimate of power and energy losses due to partial equipment failure.