Abstract: The calculation of the variance of a correlation coefficient matrix for a photovoltaic fleet can be completed in linear space as a function of decreasing distance between pairs of photovoltaic plant locations. When obtaining irradiance data from a satellite imagery source, irradiance statistics must first be converted from irradiance statistics for an area into irradiance statistics for an average point within a pixel in the satellite imagery. The average point statistics are then averaged across all satellite pixels to determine the average across the whole photovoltaic fleet region. Where pairs of photovoltaic systems are located too far away from each other to be statistically correlated, the correlation coefficients in the matrix for that pair of photovoltaic systems are effectively zero. Consequently, the double summation portion of the calculation can be simplified to eliminate zero values based on distance between photovoltaic plant locations, substantially decreasing the size of the problem space.

Abstract: Statistically representing point-to-point photovoltaic power estimation and area-to-point conversion of satellite pixel irradiance data are described. Accuracy on correlated overhead sky clearness is bounded by evaluating a mean and standard deviation between recorded irradiance measures and the forecast irradiance measures. Sky clearness over the two locations is related with a correlation coefficient by solving an empirically-derived exponential function of the temporal distance. Each forecast clearness index is weighted by the correlation coefficient to form an output set of forecast clearness indexes and the mean and standard deviation are proportioned. Additionally, accuracy on correlated satellite imagery is bounded by converting collective irradiance into point clearness indexes. A mean and standard deviation for the point clearness indexes is evaluated. The mean is set as an area clearness index for the bounded area.

Abstract: Value of solar (VOS) analysis begins with the observation that photovoltaic power production represents a unique form of energy resource that is indifferent to demand and price signals. Accurate VOS assessment requires consideration of technical and economic components. The technical analysis predicts future central power generation requirements, as reflected by estimated customer demand, using an energy balance approach. A customer demand forecasting equation with three unknown values, distributed photovoltaic power production, centralized power generation, and losses associated with the centralized power generation, is solved by applying key rational assumptions in combination with historical data of centralized power generation and distributed photovoltaic power production.

Abstract: Operational specifications of a photovoltaic plant configuration can be inferred through evaluation of historical measured system production data and measured solar resource data. Based upon the location of the photovoltaic plant, a time-series power generation data set is simulated based on a normalized and preferably substantially linearly-scalable solar power simulation model. The simulation is run for a range of hypothetical photovoltaic system configurations. The simulation can be done probabilistically. A power rating is derived for each system configuration by comparison of the measured versus simulated production data, which is applied to scale up the simulated time-series data. The simulated energy production is statistically compared to actual historical data, and the system configuration reflecting the lowest overall error is identified as the inferred (and optimal) system configuration.

Abstract: A computer-implemented system and method for inferring operational specifications of a photovoltaic power generation system is provided. The operational specifications of a photovoltaic plant configuration can be inferred through evaluation of historical measured system production data and measured solar resource data. Preferably, the solar resource data includes both historical and forecast irradiance values. Based upon the location of the photovoltaic plant, a time-series power generation data set is simulated based on a normalized and preferably substantially linearly-scalable solar power simulation model. The simulation is run for a range of hypothetical photovoltaic system configurations. A power rating is derived for each system configuration by comparison of the measured versus simulated production data, which is applied to scale up the simulated time-series data.

Abstract: Statistically representing point-to-point photovoltaic power estimation and area-to-point conversion of satellite pixel irradiance data are described. Accuracy on correlated overhead sky clearness is bounded by evaluating a mean and standard deviation between recorded irradiance measures and the forecast irradiance measures. Sky clearness over the two locations is related with a correlation coefficient by solving an empirically-derived exponential function of the temporal distance. Each forecast clearness index is weighted by the correlation coefficient to form an output set of forecast clearness indexes and the mean and standard deviation are proportioned. Additionally, accuracy on correlated satellite imagery is bounded by converting collective irradiance into point clearness indexes. A mean and standard deviation for the point clearness indexes is evaluated. The mean is set as an area clearness index for the bounded area.

Abstract: A computer-implemented system and method for bounding accuracy on a forecast of photovoltaic fleet power generation is provided. Measured irradiance observations for a plurality of locations are retrieved. The measured observations include a time series recorded at successive time periods. Forecast irradiance observations are retrieved. Error between the forecast and the measured observations is identified. A mean and standard deviation of the error is determined and combined into a fleet mean and fleet standard deviation. Sky clearness indexes are generated as a ratio of each measured observation and clear sky irradiance. A time series of the sky clearness indexes is formed. Fleet irradiance statistics are determined through statistical evaluation of the sky clearness indexes time series. A time series of power statistics is generated as a function of the fleet irradiance statistics and photovoltaic fleet power rating. A statistical confidence is associated with each power statistic in the time series.

Abstract: A computer-implemented system and method for bounding accuracy on a forecast of photovoltaic fleet power generation is provided. Measured irradiance observations for a plurality of locations are retrieved. The measured observations include a time series recorded at successive time periods. Forecast irradiance observations are retrieved. Error between the forecast and the measured observations is identified. A mean and standard deviation of the error is determined and combined into a fleet mean and fleet standard deviation. Sky clearness indexes are generated as a ratio of each measured observation and clear sky irradiance. A time series of the sky clearness indexes is formed. Fleet irradiance statistics are determined through statistical evaluation of the sky clearness indexes time series. A time series of power statistics is generated as a function of the fleet irradiance statistics and photovoltaic fleet power rating. A statistical confidence is associated with each power statistic in the time series.

Abstract: A computer-implemented system and method for generating a probabilistic forecast of photovoltaic fleet power generation is provided. A temporal distance between two locations is determined in proportion to cloud speed within a geographic region. Input clearness indexes are generated as a ratio of irradiance observations for one location, and clear sky irradiance. The clearness indexes are ordered into a time series. A clearness index correlation coefficient is determined as a function of temporal distance. The input clearness indexes are weighted by the clearness index correlation coefficient to form a time series of output clearness indexes. Means and standard deviations of both time series are respectively determined and combined into fleet irradiance statistics. Deterministic fleet power statistics are forecast as a function of the fleet irradiance statistics and photovoltaic fleet power rating. A time series of the forecast power statistics is generated by applying a time lag correlation coefficient.

Abstract: A computer-implemented system and method for estimating photovoltaic power generation for use in photovoltaic fleet operation is provided. A set of sky clearness indexes is generated as a ratio of each irradiance observation in a set of irradiance observations that has been regularly measured for a plurality of locations, which are each within a geographic region suitable for operation of a photovoltaic fleet, and clear sky irradiance. A time series of the set of the sky clearness indexes is formed for all of the locations within the geographic region. Fleet irradiance statistics for the photovoltaic fleet are generated through statistical evaluation of the time series of the set of the sky clearness indexes. Power statistics for the photovoltaic fleet are built as a function of the fleet irradiance statistics and an overall power rating of the photovoltaic fleet.

Abstract: A computer-implemented system and method for correlating overhead sky clearness for use in photovoltaic fleet output estimation is provided. A temporal distance that includes a physical distance between two locations, which are each within a geographic region suitable for operation of a photovoltaic fleet, is determined in proportion to cloud speed within the geographic region. A set of input sky clearness indexes is generated as a ratio of each irradiance observation in a set of irradiance observations that has been regularly measured for one of the locations within the geographic region, and clear sky irradiance. A clearness index correlation coefficient between the two locations is determined as an empirically-derived function of the temporal distance. The set of input sky clearness indexes is weighted by the clearness index correlation coefficient to form a set of output sky clearness indexes, which indicates the sky clearness for the other of the locations.

Abstract: A computer-implemented system and method for correlating satellite imagery for use in photovoltaic fleet output estimation is provided. Pixels in satellite imagery data of overhead sky clearness is correlated to a bounded area within a geographic region. Each pixel represents collective irradiance that is converted into point clearness indexes for the points within the bounded area relative to clear sky irradiance. The point clearness indexes in the point clearness indexes are averaged for the points within the bounded area into an area clearness index. A variance of the area clearness index is determined in proportion to a physical area covered by each pixel. For each point, a variance of the point clearness index is determined as a ratio of the area clearness index variance and the physical area relative to the point clearness index, regional cloud speed, and a time interval relating to a time resolution of collective irradiance observation.

Abstract: A computer-implemented system and method for efficiently performing area-to-point conversion of satellite imagery for photovoltaic power generation fleet output estimation is provided. Satellite imagery data of overhead sky clearness for a geographic region is accessed. Pixels within the satellite imagery data corresponding to a bounded area are identified. Each pixel represents collective irradiance within the bounded area. An area clearness index for the bounded area is set as an average of point clearness indexes derived from the collective irradiance for each point. A variance of the area clearness index is expressed as an average of the variance of the point clearness indexes. The variance of the area clearness index is proportioned to an area metric corresponding to each pixel's physical coverage area. A variance of the point clearness index is determined for one point as a ratio of the variance of the area clearness index and each pixel's physical coverage.

Abstract: A computer-implemented system and method for estimating power data for a photovoltaic power generation fleet is provided. Solar irradiance data is assembled for locations representative of a geographic region. The data includes a time series of solar irradiance observations electronically recorded at successive time periods spaced at input time intervals. Each observation includes measured irradiance. The data in the time series is converted over each time period into clearness indexes relative to clear sky global horizontal irradiance and the clearness indexes are interpreted as irradiance statistics. Each location's irradiance statistics are combined into fleet irradiance statistics applicable over the geographic region. Fleet power statistics are built as a function of the fleet irradiance statistics and the fleet's power rating.

Abstract: A computer-implemented system and method for determining point-to-point correlation of sky clearness for photovoltaic power generation fleet output estimation is provided. A physical distance between two points is obtained, each point being suitable for operation of a photovoltaic station. A temporal distance that includes the physical distance between the two points in proportion to cloud speed is determined. A correlation between sky clearness over the two points is evaluated as an empirically-derived exponential function of the temporal distance. A set of input clearness indexes for one of the points is correlated into a set of output clearness indexes indicating the sky clearness for the other of the points using a coefficient of the clearness index correlation.