Mariano Sidrach de CArdona - Academia.edu (original) (raw)
Papers by Mariano Sidrach de CArdona
Renewable Energy and Power Quality Journal, 2018
Sustainable Energy-Water-Environment Nexus in Deserts
CIES2020: As Energias Renováveis na Transição Energética: Livro de Comunicações do XVII Congresso... more CIES2020: As Energias Renováveis na Transição Energética: Livro de Comunicações do XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia Solar. Helder Gonçalves, Manuel Romero (Ed.). Lisboa, Portugal: LNEG, 3-5 Novembro, 2020, p. 1377-1384. ISBN: 978-989-675-076-3
IOP Conference Series: Materials Science and Engineering, 2020
A significant number of universities have several campuses located in urban or rural settings, or... more A significant number of universities have several campuses located in urban or rural settings, or with scattered university buildings that require the use of means of transportation. This implies the mobility and potential displacement of a large community of students, professors and researchers. The use of electric bicycles (e-bikes) is an intermediate alternative between the bicycle and electric cars. It can be an important stimulus for the promotion of the decarbonisation of the University Campus, avoiding the traffic congestion and reducing space requirements for parking. This paper presents the smart solar micro-exchanger model managed through a sustainable mobility web platform, applied to the case study of the University of Malaga (Spain). It is a solar charging station for e-bike, whose design is based on the principles of solar architecture (providing great security to e-bike). It managed by a web platform and app that allows the user to make reservations and learn about th...
The energy yield of a photovoltaic plant depends on the performance of each of its single photovo... more The energy yield of a photovoltaic plant depends on the performance of each of its single photovoltaic modules. In this paper, a methodology is presented that allows calculating the losses produced in a module and identifying if it is operating properly according to given climatic conditions. The proposed model is based on the comparison between the theoretical performance ratio of a module and the resulting experimental one under given climatic conditions. The results obtained allow estimating the losses that affect a module nonoperating properly. By means of real-time monitoring at module level, the herein described experimental system together with the proposed methodology allows to quantify the module losses. The immediate corrective actions will avoid further losses in the generated energy.
E3S Web of Conferences, 2021
The Cogeneration laboratory is a research facility in the University of Málaga (UMA) that allows ... more The Cogeneration laboratory is a research facility in the University of Málaga (UMA) that allows for the behavioural study of a renewable energy installation combining solar resources and micro-CHP. Energy generation in the system is provided by a 3 kWp photovoltaic array, two solar thermal connectors and a Whispergen EU1 Stirling micro-CHP unit. Energy storage in the facility is provided by water tank and lithium-ion battery. This laboratory is managed through a programmable Mitsubishi PLC that permits the simulation of different thermal and electrical load profiles, as well as the mode of operation. The electrical energy management is controlled by the solar inverter. Environmental data, are measured using a top of the line weather station.The system’s real time status is logged through the programmable PLC. All this data is transferred and analysed in a purpose-built MATLAB-based software, where power and energy balances are conducted, efficiencies are calculated, and a CO2 emiss...
Progress in Photovoltaics: Research and Applications, 2021
In this paper, the results of the analysis of the degradation of a set of single‐crystalline sili... more In this paper, the results of the analysis of the degradation of a set of single‐crystalline silicon modules after 21 years are presented. The comparison of the main electrical parameters and the series and of the shunt resistances measured in 1996 and 2017 is performed, so that the annual degradation rate is evaluated. In addition, a detailed analysis of the parameter uncertainties has been performed in order to determine its impact on the results. A visual inspection of the modules has also been carried out in order to show the correlation with the variation of the electrical performance. Finally, the temperature coefficients of the degraded modules have been estimated and compared with the nominal ones. The results shown in the paper reveal that the mean annual degradation rate in terms of power is close to 0.9%.
WEENTECH Proceedings in Energy, 2019
In this paper the performances of self-consumption facilities for different locations are evaluat... more In this paper the performances of self-consumption facilities for different locations are evaluated. The four cities that have been analysed are Berlin, Madrid, Paris and Rome. The consumption profile corresponds to a residential consumption of 20 kWh/day. We propose to use two parameters to this evaluation: the percentage of self-consumption (PV directly consumed / total PV produced) and the percentage of self-sufficiency (PV directly consumed / total consumption). Several hypotheses have been checked attending to the size of the installation and the availability of solar resource. The size corresponding to a zero energy building has been proposed as reference power; for this reference size, the energy supplied by the PV system is approximately equal to the consumption for a one-year period of time. Using this size as a reference, several different PV sizes ranging from 0.5 to 3 times this reference size have been analyzed. For all of them, the self-sufficiency and self-consumption...
International Journal of Smart Grid and Clean Energy, 2017
A methodology for analyzing the performance of a photovoltaic self-consumption facility is propos... more A methodology for analyzing the performance of a photovoltaic self-consumption facility is proposed. It is based on the possibility of doing net metering for different time intervals. The used data were recorded for a photovoltaic facility installed in a detached house in Malaga (Spain). The peak power of the installation is 3kW. The monthly values of consumption and photovoltaic production and the energy balances of the system for 2015 have been estimated. The net metering schemes checked range from instantaneous to annual. In the firs case, no compensation between energy injected into the grid and the energy imported from the grid is allowed, while in the last case (annual values) the incentive scheme allows compensating generation and consumption for a year. The obtained results show that depending on the net-metering scheme the self-consumption ranges from 34% to 71% while the self-sufficiency ranges from 49% to 100%. In all cases, the annual energy fed into the grid is greater that the imported from the grid.
International Journal of Smart Grid and Clean Energy, 2017
The aim of this work is the validation of a regression model to forecast the cell temperature of ... more The aim of this work is the validation of a regression model to forecast the cell temperature of a photovoltaic module under different conditions from those for which it was fitted. In a previous article, a model which uses as inputs the air temperature, the incident irradiation and the wind speed was proposed to forecast the cell temperature. To know if this model could be universally used, the cell temperature of a module of the same technology installed in another location with different weather conditions has been computed using the coefficients estimated previously. From the obtained results, it can be concluded that the model is able to predict the operating temperature of the generator of a power plant and could be applied to this technology at any location regardless of the weather conditions.
WEENTECH Proceedings in Energy, 2019
A software platform has been developed in order to unify the different measurements obtained from... more A software platform has been developed in order to unify the different measurements obtained from different manufacturers. These measurements include the curve from voltage to the current of PV devices and several meteorological parameters such as global and direct irradiance, temperature level of the solar cells and spectral shape distribution of solar irradiance. The measurements are performed in an automated way by a stand-alone application that is able to communicate with a pair of multimeters and a bipolar power supply that are controlled in order to obtain the current–voltage pairs. In addition, several magnitudes, that can be configured by the user, such as irradiance, module temperature or wind speed, are incorporated to register the conditions of each measurement. Moreover, it is possible to attach to each curve the spectral distribution of the solar radiation at each moment. Independently of the source of the information, all these measurements are included in our own data...
Sustainable Cities and Society, 2018
Spanish cities, Barcelona and Malaga. The results show that it covers most of the issues related ... more Spanish cities, Barcelona and Malaga. The results show that it covers most of the issues related to the use of energy and sustainability in the cities and that it can also be applied to others cities.
This paper describes an experimental system developed in the photovoltaic laboratory at the Unive... more This paper describes an experimental system developed in the photovoltaic laboratory at the University of Málaga (Spain) to measure the current voltage curve of photovoltaic modules under outdoor conditions. The measurement is performed in an automated way by employing commercial instruments controlled by a computer using the GPIB standard. Several modules, selected sequentially through a set of relays, are biased by a four-quadrant power supply while a function generator synchronizes two multimeters in order to acquire voltage and current values. The measurement uncertainties were also estimated. The proposed method for synchronizing the voltage and current measurements ensures that these measurements are performed simultaneously; this means that the estimated uncertainty is lower than those obtained using other previously proposed methods. The main electrical parameters are estimated. A user-friendly application allows the user to configure several parameters, such as bias rate, v...
Reducing the nominal operation cell temperature (NOCT) of a PV module is one way to increase the ... more Reducing the nominal operation cell temperature (NOCT) of a PV module is one way to increase the energy yield and performance ratio of PV systems. We have built a thermal model of the PV module, in order to analyze the influence of different module design and installation parameters on the thermal performance of the system. The impact of building integrated installations on the thermal performance has been investigated. Several PV module samples with different configurations have been built and experimentally monitored in order to verify the model results. Also, the influence of the operating temperature on the energy yield of PV modules has been analyzed through simulations and experimental measurements.
A model for characterizing the solar spectral radiation distribution only using APE value as inpu... more A model for characterizing the solar spectral radiation distribution only using APE value as input parameter is proposed. Although the uniqueness of the relationship between these parameters has been previously established there is no expression that allows obtaining the solar spectral curves for each APE value. In this work the APE values for which this uniqueness works have been checked. For this, the cumulative probability distribution function for each spectrum has been estimated. Using a data mining technique, named k-means, all these curves have been clustered in five different groups. In each group a solar spectral cumulative distribution function curve known as centroid has been estimated; this curve is similar to the rest of the curves gathered in the group. The spectra distribution per clusters is quite homogeneous. The centroid of each cluster characterizes all curves in the cluster. For doing the analysis, more than two-hundred-fifty-thousands spectra have been used.
The deposition of a film with self-cleaning and anti-reflective properties on the surface of the ... more The deposition of a film with self-cleaning and anti-reflective properties on the surface of the modules reduces the soiling losses and facilitates cleaning when it rains. In this paper we present a comparative study of the performance of photovoltaic modules with and without coating in order to determine the soiling losses as well as the influence of tilt angle on these losses. Two different procedures for quantifying soiling losses have been used: The first one measuring transmittance losses of the module and the second one analyzing the values of the daily performance ratio. Measurements were carried out for two periods: the photovoltaic modules were placed with a south orientation and 21° (first period of measurements) and 40 ° (second period of measurements) tilt angles. The obtained results show that coated modules exhibit lower soiling losses that those without coating and therefore better values of daily yield. Then, soiling losses depend on the module tilt angle and are low...
JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME, 2014
The monitoring and assessment of small and medium solar energy plants were ruled out as the exist... more The monitoring and assessment of small and medium solar energy plants were ruled out as the existing programs for these tasks are expensive and they are designed to run directly on the installation site, making it necessary to have both a monitoring system, such as data logger, and specialized staff capable of analyzing the monitoring data. To address these problems, this paper presents a framework that allows the development of programs for remote monitoring and automatic evaluation of solar energy plants without using any additional hardware. Software architecture based on separating the software functionalities into several layers and on using a hierarchical model of the plant elements is proposed. This framework allows the integration of different technologies and communication protocols of devices used in solar energy plants. A monitoring and assessing program for several dispersed solar energy installations has been developed as practical example.
... control module FJ Sánchez-Pacheco(1), ), PJ Sotorrio-Ruiz(1), JR Heredia-Larrubia(1), F. Pére... more ... control module FJ Sánchez-Pacheco(1), ), PJ Sotorrio-Ruiz(1), JR Heredia-Larrubia(1), F. Pérez-Hidalgo(2), M. Sidrach-de-Cardona(3) (1) Dept. ... [3] Eduardo Román, Ricardo Alonso, PedroIbañez, Member, IEEE, Sabino Elorduizapatarietxe, and Damián Goitia. ...
Progress in Photovoltaics: Research and Applications, 2013
A novel methodology based on artificial neural networks is proposed as an alternative to algebrai... more A novel methodology based on artificial neural networks is proposed as an alternative to algebraic and numerical procedures to determine the I-V curve of a module under different conditions. Although there are methods that use neural networks for approximating the I-V curve, this is the first time that the measurement of the spectrum is incorporated as an input. In addition, a suitable selection of the training samples used to build the model is fundamental in order to get an accurate approximation. This is why a training sample selection based on a Kohonen self-organizing map is performed in this paper instead of a random selection. With the use of this preliminary step, the performance of the network trained with spectral information improves over the one without spectral information.
Solar Energy, 2003
A model to generate synthetic series of hourly exposure of global radiation is proposed. This mod... more A model to generate synthetic series of hourly exposure of global radiation is proposed. This model has been constructed using a machine learning approach. It is based on the use of a subclass of probabilistic finite automata which can be used for variable-order Markov processes. This model allows us to represent the different relationships and the representative information observed in the hourly series of global radiation; the variable-order Markov process can be used as a natural way to represent different types of days, and to take into account the ''variable memory'' of cloudiness. A method to generate new series of hourly global radiation, which incorporates the randomness observed in recorded series, is also proposed. As input data this method only uses the mean monthly value of the daily solar global radiation. We examine if the recorded and simulated series are similar. It can be concluded that both series have the same statistical properties.
Renewable Energy and Power Quality Journal, 2018
Sustainable Energy-Water-Environment Nexus in Deserts
CIES2020: As Energias Renováveis na Transição Energética: Livro de Comunicações do XVII Congresso... more CIES2020: As Energias Renováveis na Transição Energética: Livro de Comunicações do XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia Solar. Helder Gonçalves, Manuel Romero (Ed.). Lisboa, Portugal: LNEG, 3-5 Novembro, 2020, p. 1377-1384. ISBN: 978-989-675-076-3
IOP Conference Series: Materials Science and Engineering, 2020
A significant number of universities have several campuses located in urban or rural settings, or... more A significant number of universities have several campuses located in urban or rural settings, or with scattered university buildings that require the use of means of transportation. This implies the mobility and potential displacement of a large community of students, professors and researchers. The use of electric bicycles (e-bikes) is an intermediate alternative between the bicycle and electric cars. It can be an important stimulus for the promotion of the decarbonisation of the University Campus, avoiding the traffic congestion and reducing space requirements for parking. This paper presents the smart solar micro-exchanger model managed through a sustainable mobility web platform, applied to the case study of the University of Malaga (Spain). It is a solar charging station for e-bike, whose design is based on the principles of solar architecture (providing great security to e-bike). It managed by a web platform and app that allows the user to make reservations and learn about th...
The energy yield of a photovoltaic plant depends on the performance of each of its single photovo... more The energy yield of a photovoltaic plant depends on the performance of each of its single photovoltaic modules. In this paper, a methodology is presented that allows calculating the losses produced in a module and identifying if it is operating properly according to given climatic conditions. The proposed model is based on the comparison between the theoretical performance ratio of a module and the resulting experimental one under given climatic conditions. The results obtained allow estimating the losses that affect a module nonoperating properly. By means of real-time monitoring at module level, the herein described experimental system together with the proposed methodology allows to quantify the module losses. The immediate corrective actions will avoid further losses in the generated energy.
E3S Web of Conferences, 2021
The Cogeneration laboratory is a research facility in the University of Málaga (UMA) that allows ... more The Cogeneration laboratory is a research facility in the University of Málaga (UMA) that allows for the behavioural study of a renewable energy installation combining solar resources and micro-CHP. Energy generation in the system is provided by a 3 kWp photovoltaic array, two solar thermal connectors and a Whispergen EU1 Stirling micro-CHP unit. Energy storage in the facility is provided by water tank and lithium-ion battery. This laboratory is managed through a programmable Mitsubishi PLC that permits the simulation of different thermal and electrical load profiles, as well as the mode of operation. The electrical energy management is controlled by the solar inverter. Environmental data, are measured using a top of the line weather station.The system’s real time status is logged through the programmable PLC. All this data is transferred and analysed in a purpose-built MATLAB-based software, where power and energy balances are conducted, efficiencies are calculated, and a CO2 emiss...
Progress in Photovoltaics: Research and Applications, 2021
In this paper, the results of the analysis of the degradation of a set of single‐crystalline sili... more In this paper, the results of the analysis of the degradation of a set of single‐crystalline silicon modules after 21 years are presented. The comparison of the main electrical parameters and the series and of the shunt resistances measured in 1996 and 2017 is performed, so that the annual degradation rate is evaluated. In addition, a detailed analysis of the parameter uncertainties has been performed in order to determine its impact on the results. A visual inspection of the modules has also been carried out in order to show the correlation with the variation of the electrical performance. Finally, the temperature coefficients of the degraded modules have been estimated and compared with the nominal ones. The results shown in the paper reveal that the mean annual degradation rate in terms of power is close to 0.9%.
WEENTECH Proceedings in Energy, 2019
In this paper the performances of self-consumption facilities for different locations are evaluat... more In this paper the performances of self-consumption facilities for different locations are evaluated. The four cities that have been analysed are Berlin, Madrid, Paris and Rome. The consumption profile corresponds to a residential consumption of 20 kWh/day. We propose to use two parameters to this evaluation: the percentage of self-consumption (PV directly consumed / total PV produced) and the percentage of self-sufficiency (PV directly consumed / total consumption). Several hypotheses have been checked attending to the size of the installation and the availability of solar resource. The size corresponding to a zero energy building has been proposed as reference power; for this reference size, the energy supplied by the PV system is approximately equal to the consumption for a one-year period of time. Using this size as a reference, several different PV sizes ranging from 0.5 to 3 times this reference size have been analyzed. For all of them, the self-sufficiency and self-consumption...
International Journal of Smart Grid and Clean Energy, 2017
A methodology for analyzing the performance of a photovoltaic self-consumption facility is propos... more A methodology for analyzing the performance of a photovoltaic self-consumption facility is proposed. It is based on the possibility of doing net metering for different time intervals. The used data were recorded for a photovoltaic facility installed in a detached house in Malaga (Spain). The peak power of the installation is 3kW. The monthly values of consumption and photovoltaic production and the energy balances of the system for 2015 have been estimated. The net metering schemes checked range from instantaneous to annual. In the firs case, no compensation between energy injected into the grid and the energy imported from the grid is allowed, while in the last case (annual values) the incentive scheme allows compensating generation and consumption for a year. The obtained results show that depending on the net-metering scheme the self-consumption ranges from 34% to 71% while the self-sufficiency ranges from 49% to 100%. In all cases, the annual energy fed into the grid is greater that the imported from the grid.
International Journal of Smart Grid and Clean Energy, 2017
The aim of this work is the validation of a regression model to forecast the cell temperature of ... more The aim of this work is the validation of a regression model to forecast the cell temperature of a photovoltaic module under different conditions from those for which it was fitted. In a previous article, a model which uses as inputs the air temperature, the incident irradiation and the wind speed was proposed to forecast the cell temperature. To know if this model could be universally used, the cell temperature of a module of the same technology installed in another location with different weather conditions has been computed using the coefficients estimated previously. From the obtained results, it can be concluded that the model is able to predict the operating temperature of the generator of a power plant and could be applied to this technology at any location regardless of the weather conditions.
WEENTECH Proceedings in Energy, 2019
A software platform has been developed in order to unify the different measurements obtained from... more A software platform has been developed in order to unify the different measurements obtained from different manufacturers. These measurements include the curve from voltage to the current of PV devices and several meteorological parameters such as global and direct irradiance, temperature level of the solar cells and spectral shape distribution of solar irradiance. The measurements are performed in an automated way by a stand-alone application that is able to communicate with a pair of multimeters and a bipolar power supply that are controlled in order to obtain the current–voltage pairs. In addition, several magnitudes, that can be configured by the user, such as irradiance, module temperature or wind speed, are incorporated to register the conditions of each measurement. Moreover, it is possible to attach to each curve the spectral distribution of the solar radiation at each moment. Independently of the source of the information, all these measurements are included in our own data...
Sustainable Cities and Society, 2018
Spanish cities, Barcelona and Malaga. The results show that it covers most of the issues related ... more Spanish cities, Barcelona and Malaga. The results show that it covers most of the issues related to the use of energy and sustainability in the cities and that it can also be applied to others cities.
This paper describes an experimental system developed in the photovoltaic laboratory at the Unive... more This paper describes an experimental system developed in the photovoltaic laboratory at the University of Málaga (Spain) to measure the current voltage curve of photovoltaic modules under outdoor conditions. The measurement is performed in an automated way by employing commercial instruments controlled by a computer using the GPIB standard. Several modules, selected sequentially through a set of relays, are biased by a four-quadrant power supply while a function generator synchronizes two multimeters in order to acquire voltage and current values. The measurement uncertainties were also estimated. The proposed method for synchronizing the voltage and current measurements ensures that these measurements are performed simultaneously; this means that the estimated uncertainty is lower than those obtained using other previously proposed methods. The main electrical parameters are estimated. A user-friendly application allows the user to configure several parameters, such as bias rate, v...
Reducing the nominal operation cell temperature (NOCT) of a PV module is one way to increase the ... more Reducing the nominal operation cell temperature (NOCT) of a PV module is one way to increase the energy yield and performance ratio of PV systems. We have built a thermal model of the PV module, in order to analyze the influence of different module design and installation parameters on the thermal performance of the system. The impact of building integrated installations on the thermal performance has been investigated. Several PV module samples with different configurations have been built and experimentally monitored in order to verify the model results. Also, the influence of the operating temperature on the energy yield of PV modules has been analyzed through simulations and experimental measurements.
A model for characterizing the solar spectral radiation distribution only using APE value as inpu... more A model for characterizing the solar spectral radiation distribution only using APE value as input parameter is proposed. Although the uniqueness of the relationship between these parameters has been previously established there is no expression that allows obtaining the solar spectral curves for each APE value. In this work the APE values for which this uniqueness works have been checked. For this, the cumulative probability distribution function for each spectrum has been estimated. Using a data mining technique, named k-means, all these curves have been clustered in five different groups. In each group a solar spectral cumulative distribution function curve known as centroid has been estimated; this curve is similar to the rest of the curves gathered in the group. The spectra distribution per clusters is quite homogeneous. The centroid of each cluster characterizes all curves in the cluster. For doing the analysis, more than two-hundred-fifty-thousands spectra have been used.
The deposition of a film with self-cleaning and anti-reflective properties on the surface of the ... more The deposition of a film with self-cleaning and anti-reflective properties on the surface of the modules reduces the soiling losses and facilitates cleaning when it rains. In this paper we present a comparative study of the performance of photovoltaic modules with and without coating in order to determine the soiling losses as well as the influence of tilt angle on these losses. Two different procedures for quantifying soiling losses have been used: The first one measuring transmittance losses of the module and the second one analyzing the values of the daily performance ratio. Measurements were carried out for two periods: the photovoltaic modules were placed with a south orientation and 21° (first period of measurements) and 40 ° (second period of measurements) tilt angles. The obtained results show that coated modules exhibit lower soiling losses that those without coating and therefore better values of daily yield. Then, soiling losses depend on the module tilt angle and are low...
JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME, 2014
The monitoring and assessment of small and medium solar energy plants were ruled out as the exist... more The monitoring and assessment of small and medium solar energy plants were ruled out as the existing programs for these tasks are expensive and they are designed to run directly on the installation site, making it necessary to have both a monitoring system, such as data logger, and specialized staff capable of analyzing the monitoring data. To address these problems, this paper presents a framework that allows the development of programs for remote monitoring and automatic evaluation of solar energy plants without using any additional hardware. Software architecture based on separating the software functionalities into several layers and on using a hierarchical model of the plant elements is proposed. This framework allows the integration of different technologies and communication protocols of devices used in solar energy plants. A monitoring and assessing program for several dispersed solar energy installations has been developed as practical example.
... control module FJ Sánchez-Pacheco(1), ), PJ Sotorrio-Ruiz(1), JR Heredia-Larrubia(1), F. Pére... more ... control module FJ Sánchez-Pacheco(1), ), PJ Sotorrio-Ruiz(1), JR Heredia-Larrubia(1), F. Pérez-Hidalgo(2), M. Sidrach-de-Cardona(3) (1) Dept. ... [3] Eduardo Román, Ricardo Alonso, PedroIbañez, Member, IEEE, Sabino Elorduizapatarietxe, and Damián Goitia. ...
Progress in Photovoltaics: Research and Applications, 2013
A novel methodology based on artificial neural networks is proposed as an alternative to algebrai... more A novel methodology based on artificial neural networks is proposed as an alternative to algebraic and numerical procedures to determine the I-V curve of a module under different conditions. Although there are methods that use neural networks for approximating the I-V curve, this is the first time that the measurement of the spectrum is incorporated as an input. In addition, a suitable selection of the training samples used to build the model is fundamental in order to get an accurate approximation. This is why a training sample selection based on a Kohonen self-organizing map is performed in this paper instead of a random selection. With the use of this preliminary step, the performance of the network trained with spectral information improves over the one without spectral information.
Solar Energy, 2003
A model to generate synthetic series of hourly exposure of global radiation is proposed. This mod... more A model to generate synthetic series of hourly exposure of global radiation is proposed. This model has been constructed using a machine learning approach. It is based on the use of a subclass of probabilistic finite automata which can be used for variable-order Markov processes. This model allows us to represent the different relationships and the representative information observed in the hourly series of global radiation; the variable-order Markov process can be used as a natural way to represent different types of days, and to take into account the ''variable memory'' of cloudiness. A method to generate new series of hourly global radiation, which incorporates the randomness observed in recorded series, is also proposed. As input data this method only uses the mean monthly value of the daily solar global radiation. We examine if the recorded and simulated series are similar. It can be concluded that both series have the same statistical properties.