Energy Productivity of Microinverter Photovoltaic Microinstallation: Comparison of Simulation and Measured Results—Poland Case Study

Round 1

Reviewer 1 Report

The subject of this article is very interesting regarding the comparison of data estimates for photovoltaic systems, such as irradiation and amount of energy generated in a real installed system. However, the description of the method used to obtain the data lacks a lot of information. For example: the authors say that 10 panels were installed and only 3 microinverters were used, meaning that at least one of the inverters will have a different number of panels under its control. This would directly affect the results. The authors need to better explain the configuration of the PV installation, especially with regard to the three inverters used.

The authors of this article do not clearly specify what is the text innovation, since they simply take the equations used from some references and from the Homer software itself to apply in a particular case study in Poland. With this, there is no universality in the proposed text and it is an application only of Homer's tools. From what can be understood, the solar radiation profile was collected for the same period as the measurements at the PV plant when it is known that having solar radiation data available makes it easier to make a forecast of PV generation for the same period. Despite this, here are some general observations about this article:

- In materials and methods, the authors present in Fig. 3a the distribution used in the individual energy production of each panel. However, it is known that usually all panels must have as much as possible the same power, brand, model, location and have the same installation characteristics and, therefore, should not present a very significant difference in functioning between them. This would only occur, only when affected by the influence of shading which could happen only at certain times of the day. Based on the results presented in this article, everyone acted differently at all times, some much more than others. This possibility would not have a real explanation compatible with several other articles on this subject. Therefore, there was no description of how the author obtained this information, in practice (which equipment was used, times of day, conditions and accuracy). If the information was obtained directly from the inverter, the number of plates installed on it will directly affect the performance. In the same figure, different colors could be placed at each landmark to clarify which plate it represents.

- In line 74, an estimation error smaller than 1% is mentioned, but it does not mention in which time horizon the authors obtained this result. They should complement it with more information to make it more relevant;

- The introduction has a lot of literature review and does not make clear the objectives of the article, much less how the proposed methodology could contribute in this matter;

- Is this article relevant to the scientific community because it uses microinverters?

- It would be important to have a previous explanation about Fig. 1. How to understand the algorithm if you do not know what it means, for example, what is "ssrd" or "tsdr"? These definitions are only made much later in the article, but they should appear the first time the acronyms are mentioned in such a way that the reader does not have to "guess" or "pick up" them throughout the text;

- Improve the quality of Fig. 3(b) and change the point used and thus separate the day and month by slash. Also add the year of these dates to improve understanding of the figure; also improve the sharpness in Fig. 4, because the way they are, it is difficult to interpret them due to their low quality;

- Information is missing in references 14, 20, 21, 26, 27 and 30;

- Description of each equation should be Improved the and how to cite them throughout the article. As it stands, the equations were simply pulled out from different places and dumped in this article;

- The HDKR method was lacking in more detail;

- The equations used in this article are very well detailed, but maybe there could be an example at the end using the data obtained, which would help a lot in future works. In Equation 9 it is not necessary to define "PPVm" and "PPVs" again because they were already defined in Equation 8. The periods in parentheses in both equations already define the time period;

- The authors' conclusion about Homer working properly for PV installations is already well known to the scientific community.

- Throughout the article is talked about the climatic seasons of that region of Poland, but as it should be a universal article, it should be specified at least the months in which winter and summer occur.

- Line 147 does not explain how the panels connected to the three inverters were distributed? One of them got more plates. This might interfere with the results. The same happens on line 231. On line 158 the image quality is very bad making it very difficult to interpret. You do not need to use the expression "on the other hand" on line 230. On line 275, the description of the legend in the figure is missing.

It must be said that this article is very interesting in the part referring to the simulations used to estimate the values of irradiation and energy production with the panels used. These results could be used in other researches to estimate the amount of energy generated in another specific location. In general terms, this article presents a lot of relevant and important information for the area and could contribute a lot for future studies.

Author Response

Please find attached file.

Author Response File: Author Response.docx

Reviewer 2 Report

It is a research with low novelty regarding the validation of photovoltaic simulation tools. It is detailed that the novelty lies in the presence of microinverters, but this has been extensively analyzed in previous studies. Perhaps it could gain interest, especially for readers in Poland and similar latitudes, if it could establish a comparison of the incidence of shadows of the analyzed installation with respect to conventional installations with a unique inverter for the entire array, that is significantly affected by punctual shadows.

 

A necessary aspect to clarify is that the climatic and irradiation information is calculated. If It is not, is it possible to have input from a climatic station?

 

On the other hand, it would be essential to establish the economic comparison of the installation cost with microinverters compared to installations with an inverter and subject to shadow effects... thereby specifying if there is definitely an advantage of microinverters. I tentatively dare to think that the shadows as the photovoltaics are placed with incidence mainly in winter when the irradiation is low probably this type of installation may not be profitable, in any case, that analysis should be included in this research, I think that  it should not significantly extend the manuscript

 

Author Response

Please find attached file

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Your corrected version seems to be alright now.

Reviewer 2 Report

The research is probably and above all of local interest, the validation of the results of a tool with respect to real readings in photovoltaics is not very new. Perhaps a contribution regarding the potential of an installation with microinverters compared to one with an inverter could be valuable because it remains up in the air.