Assessment of a practical model to estimate the cell temperature of a photovoltaic module

Instantaneous solar irradiance profiles or solar irradiation data collected with small time intervals (e.g., minutes) are usually required for the energy simulation of photovoltaic systems, especially as concerns the estimation of the cell temperature. However, meteorological stations and technical standards often provide just monthly average values of the horizontal daily solar irradiation; extensive climate databases which make available up to date hourly observation data, or satellite-derived data are seldom available. The goal of the present paper is to investigate the suitability and the accuracy of a methodology aimed at estimating the time profile of the cell temperature of a photovoltaic system on the basis of only the monthly mean values of the daily global irradiation on a horizontal surface. The methodology consists of a chain of well-established models which are applied one after another, in a step-by-step procedure, in order to derive the cell temperatures from the solar radiation data. In particular, we selected different models as possible candidates for each step of the methodology and compared their predictions with measured data to identify the most suitable ones. In addition, we tried several combinations of models in order to identify the most accurate combination. Comparisons with data measured in Rome confirm the suitability of the proposed approach and give information about its accuracy

Power Grid Waveform Analysis: Demonstration Test Report

Galileo Research & Development Activities Third Call - HARRISON Project - Work Package Final Repor

Simplified Conservative Measurements Of Touch And Step Voltages

Protection against electric shock requires grounding systems that must be designed primarily to keep touch voltage (Et> and step voltage (Es) to a safe value. Testing of the efficiency of a grounding system is mandatory to verify the capability to satisfy the protection requirements at the end of the construction and periodically in the following. With urban development and buildings growth adjacent to power systems, grounds systems that are not metallically connected may often be found. They are thus significantly interdependent as they are located in each other's area of influence and particularly it is useful to consider Ground Potential Difference (GPD). This situation causes a series of problems in terms of electrical compatibility and personnel safety. It becomes increasingly difficult to choose suitable locations for test probes to make resistance, Et and Es tests of a grounding system. Accuracy of tests requires reaching remote earth and for large grounds the spacing required may not be practical or even possible. Unfortunately accurate measure is often unfeasible, owing to the additional difficulty to measure both the hazardous voltages of the ground system, where test ground current flows, and the hazardous voltages of influenced ground systems. Since the rigorous measure can result too much laborious or too much expensive, a simplified conservative testing method of the behavior of ground electrodes can be favorable. This paper discusses an approach to the abovesimplified testing method, which relies on single, or multiple auxiliary electrodes placed at short distance from the grounding system. By means of this approach, a conservative test can be made of both touch voltage (Et) and step voltage (E,) and Ground Potential Difference