A power and energy procedure in operating photovoltaic systems to quantify the losses according to the causes

Recently, after high feed-in tariffs in Italy, retroactive cuts in the energy payments have generated economic concern about several grid-connected photovoltaic (PV) systems with poor performance. In this paper the proposed procedure suggests some rules for determining the sources of losses and thus minimizing poor performance in the energy production. The on-site field inspection, the identification of the irradiance sensors, as close as possible the PV system, and the assessment of energy production are three preliminary steps which do not require experimental tests. The fourth step is to test the arrays of PV modules on-site. The fifth step is to test only the PV strings or single modules belonging to arrays with poor performance (e.g., I-V mismatch). The sixth step is to use the thermo-graphic camera and the electroluminescence at the PV-module level. The seventh step is to monitor the DC racks of each inverter or the individual inverter, if equipped with only one Maximum Power Point Tracker (MPPT). Experimental results on real PV systems show the effectiveness of this procedure

Optimisation of Generation Models for Clusters of Photovoltaic Plants

The present work analyses the actual production profiles of a group of tens of thousands of PV plants. Actual PV generation profiles are represented as hourly average powers gathered from the energy meters measured at the point of common coupling with the grid. After filtering, data cleaning and statistical analysis, reference PV plants are selected for the improvements of the PV generation models. Production profiles are calculated by using literature generation models, with weather data as inputs. An optimisation is performed on the parameters of the literature models to minimise the differences between the cumulative distribution functions of calculated profiles and measured data. The study compares the performance of the different models and shows how the optimisation increases the quality of the calculated profiles

Long-term monitoring of photovoltaic plants

Peer Reviewe

Impact of a photovoltaic plant connected to the MV network on harmonic distortion: an experimental assessment

Universitatea Politehnica din Bucuresti (UPB) Scientific Bulletin, Series C (ISSN 2286 – 3540), Vol. 75, Issue 4, 2013, pp. 179-19

Statistical Validation and Power Modelling of Hourly Profiles for a Large-Scale Photovoltaic Plant Portfolio

In the last decades, the number of photovoltaic (PV) generators significantly increased over the world. An accurate analysis of the massive data gathered from the meters of the PV plants can improve the management of their intermittent generation. This paper presents a methodology to analyse the production profiles of a portfolio of thousands of PV plants installed in an Italian region. The procedure faces the problem of filtering poor and incomplete data, then uses a stratified sampling technique for the statistical validation of the remaining profiles. Finally, the checked production profiles are used to adjust the energy model to better match the measured data and calculate the whole PV portfolio production

Recent progress of the rulemaking on grid-connected photovoltaic generation

The rationale for the connection of distributed generators to the grid in case of abnormal events has been recently changed, passing from the obligation to switch the local generation off to the requirement of keeping it on within a certain range of frequency and voltage variations with respect to the rated values. This paper summarizes the concepts according to which the new requirements have been set up, with particular reference to the photovoltaic (PV) systems connected to Medium Voltage and Low Voltage systems, and overviews the recent upgrades of the Italian rulemaking process. A real case example showing the voltage and current waveforms during the disconnection of the PV generation within a power plant is presented

Long-Term Monitoring of Photovoltaic Plants

This paper deals with a data-acquisition system that has been specifically developed for a long-term monitoring of ten different photovoltaic plants. The main goals of the system consist in estimating the drift of the plant components, mainly photovoltaic modules and power inverters, and comparing the performance of the ten plants, which are based on different technologies and architectures. Owing to these goals, the traceabilityassurance of the obtained measurements is mandatory, hence the data-acquisition system has been designed to be easily calibrated and, if necessary, adjusted to compensate for measuring-chain drifts. In addition, the measurement uncertainty, which has to be suitable to distinguish the behaviour of the different PV plants, has to be stated for each of the estimated parameters. A brief description of the data-acquisition system is provided and its measurement capabilities are highlighted in terms of measured quantities and expected uncertainty. Results that refer to a period of thirty months are also reported

Long-Term Monitoring of Photovoltaic Plants

This paper deals with a data-acquisition system that has been specifically developed for a long-term monitoring of ten different photovoltaic plants. The main goals of the system consist in estimating the drift of the plant components, mainly photovoltaic modules and power inverters, and comparing the performance of the ten plants, which are based on different technologies and architectures. Owing to these goals, the traceabilityassurance of the obtained measurements is mandatory, hence the data-acquisition system has been designed to be easily calibrated and, if necessary, adjusted to compensate for measuring-chain drifts. In addition, the measurement uncertainty, which has to be suitable to distinguish the behaviour of the different PV plants, has to be stated for each of the estimated parameters. A brief description of the data-acquisition system is provided and its measurement capabilities are highlighted in terms of measured quantities and expected uncertainty. Results that refer to a period of thirty months are also reported

Maintenance Activity, Reliability, Availability, and Related Energy Losses in Ten Operating Photovoltaic Systems up to 1.8 MW

In general, photovoltaic (PV) plants do not include components with moving parts and, as a consequence, they are wrongly considered maintenance-free. Thus, this article presents a maintenance, reliability, and availability analysis of ten PV systems, with different inverter configurations, in the context of the intermittent renewable energy source systems, including the wind farms. The first part of the analysis consists of the evaluation of reliability using failure rates from the literature. In the second part, these results are compared with data obtained from industrial maintenance reports in the years 2016-2018. Finally, the yearly energy losses and the availability of each PV plant are assessed