A new method for estimating insolation based on PV-module currents in a cluster of stand-alone solar systems (original) (raw)
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Solar Energy, 2006
In order to evaluate the performance of solar home systems (SHS), data on local insolation is a prerequisite. We present the outline of a new method to estimate insolation if direct measurements are unavailable. This method comprises estimation of daily irradiation by correlating photovoltaic (PV)-module currents from a number of solar home systems, located a few kilometres apart. The objective is to obtain reliable daily and monthly insolation figures that are representative for an area of a few square kilometres.
Characterization of insolation data for use in photovoltaic system analysis models
1988
A statistical technique to characterize insolation data for use in photovoltaic (PV) systems is presented. We start by examining the frequency distribution of long-term insolation data. The histogram is generated for observed insolation for a particular hour over a month for a number of years. It is fitted to three distributions (Weibull, /? and log normal). Four goodness-of-fit criteria are employed in checking the best fit. These are Chi-square, Kolmogorov-Smirnov, Cramer-Von Mises-Smimov, and log-likelihood. SOLMET data from Sterling, Va, Raleigh-Durham, N.C. and Miami, Fla are analyzed. It is found that the B distribution fits the long-term hourly global horizontal insolation data best for these three southeastern U.S. locations.
Solar Energy, 1994
In this paper, the question of satellite-derived irradiance is addressed on two levels. First, the question of physical accuracy is addressed by comparing satellite-predicted hourly/daily global and direct irradiance with controlled ground measurements in climatically distinct environments. This accuracy is compared to the error made as a function of distance when extrapolating the needed data from the closest ground measurement site. Second, the question of end-use accuracy is addressed by comparing satellitederived, photovoltaic-utility load-match benchmarks with actual benchmarks for three US electric utilities where ground measurements were available.
Validation of PV performance Models using satellite-based irradiance measurements: a case study
2010
Photovoltaic (PV) system performance models are relied upon to provide accurate predictions of energy production for proposed and existing PV systems under a wide variety of environmental conditions. Ground based meteorological measurements are only available from a relatively small number of locations. In contrast, satellitebased radiation and weather data (e.g., SUNY database) are becoming increasingly available for most locations in North America, Europe, and Asia on a 10x10 km grid or better. This paper presents a study of how PV performance model results are affected when satellitebased weather data is used in place of ground-based measurements.
A sinusoidal model to assess PV generation from daily irradiation data
J. Renewable Sustainable Energy , 2019
The estimation of photovoltaic (PV) efficiency depends on the solar cell temperature, which varies with 13 ambient temperature and solar irradiation. When only daily averages are available, for instance when 14 assessing solar potential in a future climate, the standard procedure leads to a non-negligible error in the 15 estimation of PV generation, as it disregards the fact that changes in efficiency at low irradiance are less 16 relevant than changes in efficiency at high irradiance. A correction factor based on a sinusoidal model for 17 solar irradiation and temperature is proposed and tested for locations with diverse latitudes and climates. 18
Procedures for the performance check of grid-connected PV systems can significantly increase the overall efficiency of PV integration. As for a general applicability no additional local data acquisition except monthly energy meter readings should be necessary, the radiation and temperature data must be derived from remote sources, i.e. data from common meteorological surface networks and/or satellite images. A respective procedure has been developed within the EC-Joule project PVSAT. Site specific hourly irradiance data are derived from METEOSAT satellite images while monthly temperature data are used from the surface network. For the characterization of the PV system, only easily available information should be required. The set of information used by the PVSAT routine comprises the installed power, the types of generator and inverter, the orientation of the generator and a simple description of obstructions/shading to the generator. A test phase of the PVSAT procedure with systems of voluntary participants ended with the result that the monthly yield of well described and properly operating systems can be calculated within an accuracy range of about 15 kWh/kW p . For an increased understanding of the sources of these errors, an in-depth analysis of the procedure has been performed using data from monitored and supervised systems. For these systems, the accuracy of the derivation of both the irradiance information from satellite data and of the estimation of the output of the PV generator were analyzed.
Sustainability
Access to reliable, clean, modern cooking enhances life chances. One option is photovoltaic cooking systems. Accurate solar data are needed to ascertain to what extent these can satisfy the needs of local people. In this paper, we investigate how to choose the most accurate satellite-derived solar irradiance database for use in Africa. This is necessary because there is a general shortage of ground measurements for Africa. The solar data are needed to model the output of solar cooking systems, such as a solar panel, battery and electric pressure cooker. Four easily accessible global horizontal irradiation (GHI) satellite databases are validated against ground measurements using a range of statistical tests. The results demonstrate the impact of the mathematical measure used and the phenomenon of balancing errors. Fitting of the satellite model to the appropriate climate zone and/or nearby measurements improves accuracy, as does higher spatial and temporal resolution of input paramet...
Long-term measurements of energy production of solar photovoltaic panels
20th International Scientific Conference Engineering for Rural Development Proceedings, 2021
This article deals with the forecast of solar energy in Latvia. Latvia characterizes with rather low irradiances and high nebulosity, but long days in summer in comparison to traditional solar energy using in the southern countries. Two stationary mounted and two tracking to sun solar photovoltaic (PV) panels Solet 60.6-WF-250, the surface area 1.6 square meters for each, are studied in this article. Measurements are done in Ulbroka, Latvia, on the roof of the Ulbroka Scientific Centre. Energy produced by panels is entered into the public electricity grid using the solar micro invertor Enphase with MPPM function and registered by Envoy. The Enphase Micro inverter converts the DC output of the PV module into grid-compliant AC power and continuously adjusts electrical parameters for the maximum power gain. Daily energy sums are registered from April 1 till December 31 of 2020. Daily energy sum from the mentioned system can reach 10 kWh on a clear summer day, but in November and December the daily energy sum produced is near to zero. Total energy gain from the mentioned system (with total area of solar panels 6.4 square meters) in the whole mentioned time period is approximately 940 kWh. Measurements are compared to theoretical daily energy sums of solar radiation taking into account also nebulosity. Data on the nebulosity are taken from the public homepage of the Latvia Environment, Geology and Meteorology Centre. Such comparison allows to estimate real efficiency of panels. We obtained the efficiency 12-13%, what is little bit less than 15% given in the technical characteristics of the panel given by the producer. Described calculations can be used for forecast of received solar energy if nebulosity forecast (real or many years mean for every day) is known. The method can be used for any location worldwide.
Global Solar Insolation Estimation and Investigation: A Case Study of Various Nations and Cities
IEEE Access, 2021
Solar insolation is sun radiation converted to electrical energy and injected into the utility network using grid-connected solar power plants. Recently, in many nations’ electricity grids, the share of power generated using solar photovoltaic (PV) power plants is rapidly increasing. In this case study, solar insolation levels on different latitudes with fix & two seasonal tilt angles have been measured using Meteonorm® software. For these latitudes, fourteen airport locations have been chosen across the globe. From the case study, it has been evident that a double seasonal tilt angle provides more global insolation as compared to fix tilt angle with a suitable azimuth angle. There is also a reduction in insolation level at fixed and two seasonal tilt angles if going away from the equator. Further, up to three seasonal tilt angles, there is sufficient enhancement has been observed in solar insolation. It is also analyzed that for multiple seasonal tilt angle based solar PV Plant, mo...
Journal of Renewable and Sustainable Energy, 2019
Global horizontal irradiance (GHI) is typically used to model the potential of distributed photovoltaic (PV) generation. On the one hand, satellite estimations are non-pervasive and already available from commercial providers, but they have a limited spatiotemporal resolution. On the other hand, local estimations, e.g., from pyranometers, sky-cameras and monitored PV plants, capture local irradiance patterns and dynamics, but they require insitu monitoring infrastructure and upgrading the asset of electrical operators. Considering that in most power systems, PV generation is typically the aggregated contribution of many distributed plants, are local GHI estimations necessary to characterize the variability of the power flow at the grid connection point (GCP) and detect violations of the limits of voltages and line currents accurately? To reply, we consider GHI measurements from a dense network of pyranometers (used to model the ground truth GHI potential), satellite estimations for the same area, and information about a medium and low voltage distribution system. We perform load flows at different levels of installed PV capacity and compare the nodal voltages, line currents, and the power at the GCP when the irradiance is from pyranometers and when from satellite estimations, deriving conclusions on the necessity, or not, of highly spatiotemporally resolved irradiance estimations.