Abstract
The accessibility of reliable local solar resource data plays a critical role in the evaluation and development of any concentrating solar power (CSP) or photovoltaic (PV) project, impacting the areas of site selection, predicted output, and operational strategy. Currently available datasets for prediction of the local solar resource in south Louisiana rely exclusively on modeled data by various schemes. There is a significant need, therefore, to produce and report ground measured data to verify the various models under the specific and unique ambient conditions offered by the climate presented in south Louisiana. The University of Louisiana at Lafayette has been recording onsite high-fidelity solar resource measurements for the implementation into predictive models and for comparison with existing datasets and modeling resources. Industry standard instrumentation has been recording direct normal irradiance (DNI), diffuse horizontal irradiance (DHI), and global horizontal irradiance (GHI), as well as meteorological weather data since 2013. The measured data was then compared statistically to several available solar resource datasets for the geographic area under consideration. Two years of high-fidelity solar resource measurements for a location in south Louisiana that were previously not available are presented. Collected data showed statistically good agreement with several existing datasets including those available from the National Solar Radiation Database (NSRDB). High variability in year-over-year monthly DNI due to cloud cover was prevalent, while a more consistent GHI level was observed. The analysis showed that the datasets presented can be utilized for predictive analysis on a monthly or yearly basis with good statistical correlation. High variability in year-over-year monthly DNI due to cloud cover was prevalent, with as much as a 70 % difference in monthly DNI values observed in the measured data. A more consistent GHI level was observed since the GHI is less susceptible to cloud cover transients. Collected data showed statistically good agreement with several existing datasets including those available from the NSRDB when forecasting was for monthly and yearly intervals.
Highlights
The available solar resource is typically measured as a combination of several components of the solar radiation that reaches the ground [8]
The Direct normal irradiance (DNI) is of particular interest to concentrating solar power (CSP) projects since the DNI is the component of the solar radiation which can be concentrated and of particular interest to this study for the operational performance analysis of the solar thermal power plant at UL Lafayette
This paper has provided the results of 2 years of highfidelity solar resource measurements for a location in south Louisiana that was previously not available
Summary
Weather station setup Solar radiation measurements were taken onsite by a weather station consisting of a Kipp and Zonen SOLYS 2 Sun Tracker with CHP1 pyreheliometer and CMP10 pyranometers (Figs. 5 and 6). The maximum values pertaining to each case (hourly irradiance, daily and monthly average insolation) of DNI and GHI measurement are provided, where the reference values used to calculate the NRMSE can be found and used for similar relative comparisons of MAE and MBE. Figure plots the predicted daily energy delivered by the solar thermal power plant based on the TMY3 dataset, the cosine adjustment, estimated efficiency, and aperture area (1050 m2), while Fig. gives the monthly total energy output, a more stable predictor. Due to experimental and testing operations, the solar thermal power plant has not yet operated during every available resource day, preventing the generation of measured data to compare to the modeled data over the course of months or a year. Actual PV production data was not available at the time of this study; it will be presented in future work
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