Mathieu David

University of Reunion Island · Laboratory of Physics and Mathematical Engineering for Energy and the Environment (PIMENT)

Microgrids, which promote the production and consumption of renewable energy on site, are a relevant solution to reduce carbon emissions and the price of energy for end users. However, converting an existing building stock into a microgrid powered mainly by renewable energy requires finding a technical and economic optimum while taking into account...

The “Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications” provides best practices for obtaining and applying solar resource data across a range of solar technologies, including photovoltaics (PV), solar heating and cooling, and concentrating solar power (CSP). A particular focus is placed on the i...

With the fast increase of solar energy plants, a high-quality short-term forecast is required to smoothly integrate their production in the electricity grids. Usually, forecasting systems predict the future solar energy as a continuous variable. But for particular applications, such as concentrated solar plants with tracking devices, the operator n...

In this work, we propose a method to couple the behaviour models developed with Python in a previous paper with the dynamic thermal simulation software EnergyPlus, an advanced code used in research and design. The proposed coupling method is applied to the thermal model of an office building situated in the humid tropical climate of Reunion Island...

In the realm of solar forecasting, it is common to use a clear sky model output to deseasonalise the solar irradiance time series needed to build the forecasting models. However, most of these clear sky models require the setting of atmospheric parameters for which accurate values may not be available for the site under study. This can hamper the a...

This work proposes a methodology based on the probabilistic dynamic programming (PDP) to integrate operational probabilistic forecasts of a photovoltaic (PV) plant into the optimization of the day-ahead schedule of an energy storage system (ESS). The proposed approach is tested on a microgrid based on a real educational building, a PV farm and Li-i...

This paper focuses on the modelling of occupant behaviour in the case of a non-residential mixed-mode building on the tropical island of La Réunion. For such areas and types of buildings, occupants can operate passive solutions to achieve comfort while energy-consuming ones can offer alternatives during the hottest months. Yet, compared to other cl...

Renewable Energy (RE) sources are being used nowadays to overcome grid instability. A different hybrid model is used to balance energy production, reducing excess energy where PV (Photovoltaic) production is highly stochastic due to fluctuations in irradiance and temperature. The main problem of renewable energy sources is uncertainty. The velocity...

In this work we implement, evaluate and compare two methods to detect surface azimuths. The first method (PA) is new, and the second one (BBSD) is a variation of an existing method.

Azimuth misalignment of receiver surfaces is a frequent source of uncertainty when working with solar irradiance measurements on tilted surfaces (GTI). Two complementary methods to estimate the true azimuth of a tilted surface from GTI data are implemented and evaluated; the first method being a new one, and the second a variation of a previously e...

In this paper, we present the results obtained by modelling the users' behaviours in a mixed mode office building in a tropical climate, more exactly in La Réunion. Few specific research studies on comfort in tropical climates have been published, and there is little feedback on the users' behaviour in these buildings. In order to improve users' as...

The increase in solar power generation has a direct impact on the management of the electrical grids, therefore knowing the resource availability for the next few hours and days becomes essential. In this article we present a performance evaluation of the solar predictions provided by the European Centre of Medium-Range Weather Forecasts (ECMWF) in...

During the last decade, numerous solar forecasting tools have been developed to predict the energy generation of photovoltaic (PV) farms. The quality of solar forecasts is assessed by comparing predictions with measured solar data. However, this methodology does not consider the added value of the forecasts for their applications. As a consequence,...

Probabilistic solar forecasting is becoming a major topic in the solar research community as it provides more information about the uncertainty of the forecast compared to deterministic forecasting. However, to facilitate the adoption of probabilistic forecasts within solar forecasting communities (industry and academic), the definition and the use...

In this paper, the performances of two approaches for solar probabilistic are evaluated using a set of metrics previously tested by the meteorology verification community. A particular focus is put on several scores and the decomposition of a specific probabilistic metric: the continuous rank probability score (CRPS) as they give extensive informat...

Based on the reported literature and commonly used metrics in the realm of solar forecasting, a new methodology is developed for estimating a metric called forecastability (F). It reveals the extent to which solar radiation time series can be forecasted and provides the crucial context for judging the inherent difficulty associated to a particular...

In this work, three models are built to produce intra-day probabilistic solar forecasts with lead times ranging from 10 minutes to 3 hours with a granularity of 10 minutes. The first model makes only use of past ground measurements. The second model upgrades the first one by adding a variability metric obtained also from the past ground measurement...

Accurate solar forecasts is one of the most effective solution to enhance grid operations. As the solar resource is intrinsically uncertain, a growing interest for solar probabilistic forecasts is observed in the solar research community. In this work, we compare two approaches for the generation of day-ahead solar irradiance probabilistic forecast...

The field of energy forecasting has attracted many researchers from different fields (e.g., meteorology, data sciences, mechanical or electrical engineering) over the last decade. Solar forecasting is a fast-growing subdomain of energy forecasting. Despite several previous attempts, the methods and measures used for verification of deterministic (a...

We propose a framework for evaluating the quality of solar irradiance probabilistic forecasts. The verification framework is based on visual diagnostic tools and a set of scoring rules mostly originating from the weather forecast verification community. Two types of probabilistic forecasts are used as a basis to illustrate the application of these...

Optimal management of micro-grids requires anticipating the supply-demand unbalance. This work aims at developing a method to integrate real day-ahead deterministic forecasts of photovoltaic (PV) production and of system loads in the management of an ESS integrated inside a micro-grid. Dynamic Programming (DP) has been chosen to optimize the cost o...

This paper presents the Post Occupancy Evaluation of the first naturally ventilated lecture theatre built in a tropical region. The challenge was to design a bioclimatic amphitheatre of 550 seats, which does not use air conditioning and remains comfortable at the same time. A post-occupancy evaluation has been carried out based on, in parallel, ind...

One of the handicaps of the large-scale integration of solar energy is due to its variability and its intermittency. The main way to overcome this issue is the energy storage technology. Knowing the high cost of batteries and their impact on the environment, we simulate a storage system based on compressed air and acting as a battery system. The CA...

In this paper, the geographical dispersion of PV installations and Energy Storage System (ESS) are studied to smooth PV production on Reunion Island. Despite the small area of the Island, the results show that with dispersion at the total grid scale, the variability driven by weather conditions (unpredictable variability) is almost removed. Then a...

Accurate solar forecasts are necessary to improve the integration of solar renewables into the energy grid. In recent years, numerous methods have been developed for predicting the solar irradiance or the output of solar renewables. By definition, a forecast is uncertain. Thus, the models developed predict the mean and the associated uncertainty. C...

En raison de la variabilité et de l'intermittence de l'énergie solaire photovoltaïque, son intégration à grande échelle dans le mix énergétique de micro-réseaux intégrant différents moyens de production demeure compliquée. Une des solutions pour surmonter ces handicaps est le stockage d'énergie qui est généralement basé sur l'utilisation de batteri...

In contrast to deterministic forecasts, probabilistic forecasts give additional information about the inherent uncertainty embodied in weather predictions. In the realm of solar forecasting, prediction intervals are especially important to assess risks in grid operations and to optimize the energy storages needed to ensure the supply–demand balance...

This chapter aims at characterizing and modeling solar resource variability. It is shown that understanding solar energy variability requires a definition of the temporal and spatial context for which variability is assessed. This research describes a predictable, quantifiable variability-smoothing space–time continuum from a single point to thousa...

This work compares the performance of machine learning methods (k-nearest-neighbors (kNN) and gradient boosting (GB)) in intra-hour forecasting of global (GHI) and direct normal (DNI) irradiances. The models predict the GHI and DNI and the corresponding prediction intervals. The data used in this work include pyranometer measurements of GHI and DNI...

In this work, we assess the performance of three probabilistic models for intra-day solar forecasting. More precisely, a linear quantile regression method is used to build three models for generating 1 h–6 h-ahead probabilistic forecasts. Our approach is applied to forecasting solar irradiance at a site experiencing highly variable sky conditions u...

L’intégration à grande échelle des énergies renouvelables devient de plus en plus nécessaire pour l’accomplissement de la transition énergétique envisagée par de nombreux pays lors de la conférence des parties en 2016 (COP22 à Marrakech). Il est connu que la faiblesse majeure de certaines sources renouvelables comme le solaire demeure leur variabil...

Isolated power systems need to generate all the electricity demand with their own renewable resources. Among the latter, solar energy may account for a large share. However, solar energy is a fluctuating source and the island power grid could present an unstable behavior with a high solar penetration. Global Horizontal Solar Irradiance (GHI) foreca...

Due its intermittency, the large-scale integration of solar energy into electricity grids is an issue and more specifically in an insular context. Thus, forecasting the output of solar energy is a key feature to efficiently manage the supply-demand balance. In this paper, three short term forecasting procedures are applied to island locations in or...

Meeting the demand in electricity for houses or buildings provided by means of photovoltaic panels is relatively tricky, especially because of the stochastic character of solar radiation. There are some solutions in terms of storage and among them, the one consisting in converting electricity in high-pressure compressed air, seems promising. This o...

Forecasting of the solar irradiance is a key feature in order to increase the penetration rate of solar energy into the energy grids. Indeed, the anticipation of the fluctuations of the solar renewables allows a better management of the production means of electricity and a better operation of the grid-connected storage systems. If numerous methods...

In the French overseas departments and in Corsica, insular territories, as well as in Provence, south of France, where the electric grid is weakly interconnected because of the proximity of the Mediterranean Sea and the Alps Mountains, a very high proportion of photovoltaic power will be introduced in the electric grids in the near future. In order...

In this paper a techno-economic comparison of an energy storage system (ESS) sizing for three intermittent renewables, wind, wave and PV power, with regard to two electricity grid services is presented. The first service consists of output hourly smoothing, based on day-ahead power forecasts (S1). The second service supplies year-round guaranteed p...

L'intégration à grande échelle de l'énergie photovoltaïque aux réseaux électriques décentralisés est souvent difficile à cause du caractère intermittent et variable de la ressource solaire qui peut provoquer l'instabilité du réseau. Pour ces mêmes raisons, rendre autonome des bâtiments tertiaires ou résidentiels par le photovoltaïque (seul) s'avère...

La recherche de confort thermique dans les bâtiments en zone tropicale est aujourd'hui un des grands postes de consommation électrique, notamment en raison d'une utilisation fréquente de climatiseurs à compression durant les périodes de fortes chaleurs. Une alternative possible est l'utilisation de systèmes de rafraîchissement solaire permettant d'...

The conversion of renewable energies such as solar or wind is usually difficult due to their intermittency and their variability. Reunion Island, a tropical French island situated 200 km off the West coast of Mauritius, has no possibilities to be grid connected to other countries. As the island expects to reach the electric autonomy by 2030, Renewa...

This paper investigates the relationship between two parameters characterizing a given location on a given day: the daily clear skyindex KT* and the intraday variability given by the standard deviation of the changes in the hourly clear sky index rðDktDtÞ. Empiricalevidence assembled from twenty climatically distinct locations led us to derive a si...

This paper aims at assessing the accuracy of different solar forecasting methods in the case of an insular context. Two sites of La Réunion Island, Le Tampon and Saint-Pierre, are chosen to do the benchmarking exercise. Réunion Island is a tropical island with a complex orography where cloud processes are mainly governed by local dynamics. As a con...

Solar forecasting has become an important issue for power systems planning and operating, especially in islands grids. Power generationand grid utilities need day ahead, intra-day and intra-hour Global Horizontal solar Irradiance (GHI) forecasts for operations. Inthis paper, we focus on intra-day solar forecasting with forecast horizons ranging fro...

In this paper we propose to determinate and to test a set of statistical parameters (20) in order to estimate the short term predictability of the global horizontal irradiation time series and thereby to propose a new prospective tool indicating the expected error regardless the forecasting methods, a modeler can possibly implement. The mean absolu...

In this paper we propose to determinate and to test a set of statistical parameters (20) to estimate the predictability of the global horizontal irradiation time series and thereby propose a new prospective tool indicating the expected error regardless the forecasting methods a modeller can possibly implement. The mean absolute log return, which is...

Mes activités de recherche et d’enseignement au sein du laboratoire de Physique et Ingénierie Mathématique pour l’Énergie le bâtiment et l’environnemeNT (PIMENT), de l’École Supérieure d’Ingénieurs Réunion Océan Indien, de l’IUT de Saint-Pierre et de l’UFR Sciences de l’Homme et de l’Environnement de l’Université de La Réunion contribuent au dévelo...

Because of their low cost, small air conditioning systems (AC) like split air conditioning systems are often installed without a proper study of building envelope performance. Furthermore, these systems are sometimes installed by tradesmen who neglect to comply with the appropriate rules and regulations. Finally, when routine maintenance is not rig...

This paper presents a technico-economical analysis of a Pelamis wave power generator coupled with a proposed air compression storage system. Ocean wave measurements and forecasts are used from a site near the city of Saint-Pierre in Réunion island, France. The insular context requires both smoothing and forecast of the output power from the wave po...

Producing electricity for houses or buildings often provided by mean of photovoltaic panels is relatively tricky especially because of the stochastic character of the solar radiation and of the storage influence. There exist some solutions and among them, the one consisting in converting electricity in high-pressure compressed air seems promising....

In this work, we investigate the use of artificial neural networks (ANNs) as a post-processing technique in order to improve mesoscale WRF solar radiation outputs. More precisely, one day ahead (with a 1h temporal resolution) global horizontal irradiance (GHI) forecasts calculated by the WRF model are bias-corrected through the use of an ANN. ANNs...

Some small territories, such islands, actually experience a high penetration rate of PV inside a small electricity grid. In this context, the variability of the PV output is an issue for the supply-demand balance. The spatial and temporal smoothing of the variability of the PV production is an important information for the grid operator. Previous w...

In this paper, we propose a benchmarking of supervised machine learning techniques (Neural Networks, Gaussian processes and support vector machines) in order to forecast the Global Horizontal solar Irradiance (GHI). We also include in this benchmark a simple linear autoregressive (AR) model as well as two naive models based on persistence of the GH...

In building studies dealing about energy efficiency and comfort, simulation software need relevant weather files with optimal time steps. Few tools generate extreme and mean values of simultaneous hourly data including correlation between the climatic parameters. This paper presents the C++ Runeole software based on typical weather sequences analys...