Improved test method to verify the power rating of a photovoltaic (PV) project

Abstract

This paper reviews the PVUSA power rating method [1][2][3][4][5][6] and presents two additional methods that seek to improve this method in terms of model precision and increased seasonal applicability.It presents the results of an evaluation of each method based upon regression analysis of over 12 MW of operating photovoltaic (PV) systems located in a wide variety of climates. These systems include a variety of PV technologies, mounting configurations, and array sizes to ensure the conclusions are applicable to a wide range of PV designs and technologies. The work presented in this paper will be submitted to ASTM for use in the development of a standard test method for certifying the power rating of PV projects. BACKGROUND AND PURPOSE

New approaches for characterizing photovoltaic system performance

“…Previous authors have noted the seasonal differences in performance results from the PVUSA/ASTM capacity regressions [3]. To quantify the seasonal variation for each test, we calculated the standard deviation of the predicted and actual test results across all five months in the actual data (Fig.…”

“…The recently released ASTM Standard E2848-11 [2] outlines a PV performance test approach based on the PVUSA rating methodology detailed in [3] and elsewhere. This test relies on the following multi-linear regression of AC power, P, to irradiance, I, ambient temperature, T a , and wind speed, WS:…”

Pyranometers and Reference Cells: Part 2: What Makes the Most Sense for PV Power Plants?; Preprint

“…The uncertainties listed for PV reference cell irradiance measurements in Table 2 should be relatively easy to obtain as long as the PV reference cell is constructed from a stable, single junction (e.g., silicon) cell in a suitable package with a matched spectral response. In principle, PV matched reference cell measurement uncertainties of useable fuel for PV systems should not change with atmospheric conditions [3]. In all cases, the uncertainties listed assume that the measurements are implemented by a skilled individual using standard calibration protocols.…”

Analysis of Photovoltaic System Energy Performance Evaluation Method

“…The power generation of a photovoltaic (PV) system may be documented by a capacity test [1,2] that quantifies the power output of the system at set conditions, such as an irradiance of 1000 W/m 2 , an ambient temperature of 20°C, and a wind speed of 1 m/s. A longer test must be used to verify the system performance under a range of conditions.…”