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Wondering what to blame? Turn PV performance assessments into maintenance action items through the deployment of learning algorithms embedded in a Raspberry Pi device

Conference Record of the IEEE Photovoltaic Specialists Conference

Jones, C.B.; Martinez-Ramon, Manel; Carmignani, Craig K.; Stein, Joshua S.; King, Bruce H.

Monitoring of photovoltaic (PV) systems can maintain efficient operations. However, extensive monitoring of large quantities of data can be a cumbersome process. The present work introduces a simple, inexpensive, yet effective data monitoring strategy for detecting faults and determining lost revenues automatically. This was achieved through the deployment of Raspberry Pi (RPI) device at a PV system's combiner box. The RPI was programmed to collect PV data through Modbus communications, and store the data locally in a MySQL database. Then, using a Gaussian Process Regression algorithm the RPI device was able to accurately estimate string level current, voltage, and power values. The device could also detect system faults using a Support Vector Novelty Detection algorithm. Finally, the RPI was programmed to output the potential lost revenue caused by the abnormal condition. The system analytics information was then displayed on a user interface. The interface could be accessed by operations personal to direct maintenance activity so that critical issues can be solved quickly.

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TYPE Conference Poster YEAR 2016
ScopusOSTIDOI

Outdoor test and analysis procedures for generating coefficients for the Sandia Array Performance Model

Conference Record of the IEEE Photovoltaic Specialists Conference

King, Bruce H.; Hansen, Clifford H.; Riley, Daniel R.; Robinson, Charles D.; Pratt, Larry

The Sandia Array Performance Model (SAPM), a semi-empirical model for predicting PV system power, has been in use for more than a decade. While several studies have presented laboratory intercomparisons of measurements and analysis, detailed procedures for determining model coefficients have never been published. Independent test laboratories must develop in-house procedures to determine SAPM coefficients, which contributes to uncertainty in the resulting models. In response to requests from commercial laboratories and module manufacturers, Sandia has formally documented the measurement and analysis methods as a supplement to the original model description. In this paper we present a description of the measurement procedures and an example analysis for calibrating the SAPM.

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TYPE Conference Poster YEAR 2016
ScopusOSTIDOI

Statistical Approach for Determining the Sandia Array Performance Model Coefficients that Considers String-Level Mismatch

Jones, Christian B.; Hansen, Clifford H.; King, Bruce H.

Commonly used performance models, such as PVsyst, Sandia Array Performance Model (SAPM), and PV LIB, treat the PV array as being constructed of identical modules. Each of the models attempts to account for mismatch losses by applying a simple percent reduction factor to the overall estimated power. The present work attempted to reduce uncertainty of mismatch losses by determining a representative set of performance coefficients for the SAPM that were developed from a characterization of a sample of modules. This approach was compared with current practice, where only a single module’s thermal and electrical properties are testing. However, the results indicate that minimal to no improvements in model predictions were achieved.

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TYPE SAND Report YEAR 2016
OSTIDOI

Pattern Effects of Soil on Photovoltaic Surfaces

IEEE Journal of Photovoltaics

Burton, Patrick D.; Hendrickson, Alex; Ulibarri, Stephen S.; Riley, Daniel R.; Boyson, William E.; King, Bruce H.

The texture or patterning of soil on PV surfaces may influence light capture at various angles of incidence (AOI). Accumulated soil can be considered a microshading element, which changes with respect to AOI. Laboratory deposition of simulated soil was used to prepare test coupons for simultaneous AOI and soiling loss experiments. A mixed solvent deposition technique was used to consistently deposit patterned test soils onto glass slides. Transmission decreased as soil loading and AOI increased. Dense aggregates significantly decreased transmission. However, highly dispersed particles are less prone to secondary scattering, improving overall light collection. In order to test AOI losses on relevant systems, uniform simulated soil coatings were applied to split reference cells to further examine this effect. The measured optical transmission and area coverage correlated closely to the observed ISC. Angular losses were significant at angles as low as 25°.

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TYPE Journal Article YEAR 2016
ScopusOSTIDOI
Results 26–50 of 88
Results 26–50 of 88