BAH, S. Matematická optimalizace solárního fotovoltaického systému pro rodinný dům [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2019.

Posudek vedoucího

Charvát, Pavel

Sheikh Omar Bah showed a genuine interest in the topic of his master’s thesis. From the beginning, he was enthusiastically getting familiar with the concepts of solar photovoltaics (PV) systems comprising battery storage and he intensively studied mathematical models of the system components (PV modules, batteries, invertors, etc.). Certain problems occurred when he tried to use the models in mathematical optimization of the PV system. Some models were too detailed to be used in mathematical optimization without adopting metaheuristic optimization methods. An alternative approach of using time series of the performance data was chosen instead. Nonetheless, this led to other problems as the time series had too many data points to be easily handled by optimization tools. As the deadline for the completion of master’s thesis approached, Sheikh Omar Bah had to further simplify the optimization task to be able to complete his master´s thesis in time. The simplification of the optimization task decreased the relevance of the results. The time pressure, under which the master’s thesis was written, had a negative effect on the overall quality of the thesis.

Posudek oponenta

Klimeš, Lubomír

The master thesis presented by Sheikh Omar Bah is aimed at modelling and optimization of a solar photovoltaic system for the use in a residential building. The thesis consists of six chapters (45 pages) and four appendices (25 pages). The topic of the thesis is relevant and interesting in both mathematical and engineering viewpoints, but there are many serious issues (in terms of various aspects mentioned below), which make the overall quality of the thesis very low. The level of English, in which the thesis is written, is very poor. There are numerous fundamental grammatical errors and typos throughout the thesis, which make the legibility and the understanding of statements very complicated, in some cases even not possible. The pages and equations are numbered only in some cases. There are also many typographic issues, e.g. an equation going beyond the edge of the paper on page 40, a reference on page 60, a figure on page 71, etc. The flow of the text (and of the author’s ideas) is often not smooth/clear. Some figures even do not have captions. Symbols used in equations and relationships are poorly explained, often not mentioned/explained at all (e.g. equations on page 29). Many statements are vague, weird, in contradiction, trivial, or even do not make sense. For example: “we have used the most deterministic approach” (page 16), the definition of the micro-grid system (page 19), “hourly electricity load profiles were taken from our PV module” (page 28), the inclusion of the washing machine to the category of load appliances (page 29), “we can vividly deduce that the electrical characteristics of the photovoltaic panels are related to weather conditions“ (page 34), and many more. The bullet list on pages 24-25 is copy-pasted from the paper by Macedo et al. “Demand side management using artificial neural networks in a smart grid environment”, Renewable Sustainable Energy Reviews 41: 128-133 (https://doi.org/10.1016/j.rser.2014.08.035), but the original source is not acknowledged here and the reference to this paper is not mentioned/included in the thesis. Similarly, the first sentence in Section 2.6.1 (page 20) is copy-pasted from Wikipedia (the topic “Energy demand management”), but no reference to the original source is mentioned here or in the list of references. A distinct level of English used in such statements quite clearly indicates that they are adopted from other sources rather than written by the author of the thesis. Many figures are just included in the thesis, but they are not commented nor described (e.g. Figures 2-7, 23, 24). Some of them are apparently adopted from other sources but no references to those sources are mentioned (e.g. Figures 2-4). The procedure of the solution and implementation of models are not presented clearly and with sufficient details, which make the assessment of results extremely difficult. The models seem to be oversimplified, and thus the results not relevant. The presentation of results is not provided sufficiently. There are many unclear points, which are not explained in the thesis. For example, the island operation with no connection to the grid is considered for Scenario 1 (page 36), but the import of electricity from the grid is mentioned subsequently on page 37. Figure 10 - what appliances from Table 1 are used at 9 a.m. resulting in the consumption of 0.25 kWh? It seems that any their combination can result in 0.25 kWh. Moreover, should not the vertical axis be in kW rather than in kWh? Why is the constraint (4.2) on page 37 in the form of equality? Inequality should be used here, as the energy stored in the battery is not necessarily discharged completely. Moreover, the variable “k_dis” seems to be binary (according to (4.3)), while “d” is a real number indicating some incompatibility. Further, there are “k_dis” and “k_char” theoretically described on page 26 but the code on page 88 contains only “k” without any explanation. How is “k” related to “k_dis” and “k_char”? The .LO notation (page 26) in GAMS does not mean an initial value; it is a lower bound for the free variable. Where has the equation on page 25 come from? It is linear, but is it realistic? Should not be non-linear? Is it somehow related to the current-voltage characteristic of the PV panel having a parabolic shape? The load profiles are claimed as randomly generated but with no details of some assumptions is presented. The consideration of the entire year meteorological data is mentioned, but results are presented only for two days in January and June. E.q. (4.1) on page 36 cannot be considered as an objective function as it is a constraint. On page 42, you mention “These variables and parameters are defined below:” but nothing is presented below as the chapter ends here. The list of references does not serve as a list. Details of references (journal names, volumes, page ranges) are missing in many cases (e.g. [10-12, 14, 17-19]). Due to the above-mentioned serious issues, I unfortunately cannot recommend the thesis for defence.

eVSKP id 116828