Dependability Assessment of a Dual-Axis Solar Tracking Prototype Using a Maintenance-Oriented Metric System

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The maintainability of automation system is affected by many factors，so this study presents a numerical method for evaluating the maintainability of a dual-axis solar tracking system,the author propose a novel set of maintenance-oriented metrics, It is used as a method to evaluate, optimize and maintain the automation system.The practical application value of the method is verified by experiments. There are the following suggestions for the author 's reference：

1）The length of the abstract is less, and the author should add the research background of this study and the problems expected to be solved in the abstract.

2）The text in many pictures, such as figure 2, is small and not easy to read, so it is suggested to improve.

3）In Table 1, it is not necessary to put the complete topic of the article, which can be simplified.

4）There are too many less important introductions in the article, which is not conducive to highlighting the research and innovation of this article.

5）Generally speaking, the reliability index of the system will be affected by the life of one or several key components. Is the relationship between the failure mode of the system and the key components considered in this study ?

Author Response

• The length of the abstract is less, and the author should add the research background of this study and the problems expected to be solved in the abstract.

 

Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we included additional details in the Abstract regarding the main objectives of our paper. The Abstract was expanded accordingly, from lines 11-18 to lines 11-30, as can be seen in the revised manuscript on Page 1.

 

• The text in many pictures, such as figure 2, is small and not easy to read, so it is suggested to improve.

 

Response 2: Thank you for pointing this out. We agree with this comment. Consequently, we accordingly changed the font size in Figures 2,3,4 and 5. The text is now highlighted in bold and the figures were also resized to improve the identification of system components.

 

• In Table 1, it is unnecessary to put the complete topic of the article, which can be simplified.

 

Response 3: Thank you for pointing this out. We agree with this comment. Therefore, we shortened the article's topic by replacing it with a suitable description for each scientific work in Table 1.

 

• There are too many less important introductions in the article, which is not conducive to highlighting the research and innovation of this article.

 

Response 4: Thank you for pointing this out. We agree with this comment. However, to the best of our knowledge, there are only a few related works concerned with diagnosing system faults and evaluating the dependability of modern solar trackers. The majority of fault diagnosis methods are performed on fixed-tilted Photovoltaic (PV) systems as mentioned in Section 2 of the manuscript. This paper builds upon these limitations by proposing suitable verification methodologies based on our past research and current investigations, highlighting the importance of designing and constructing dependable solar tracking devices.

 

• Generally speaking, the reliability index of the system will be affected by the life of one or several key components. Is the relationship between the failure mode of the system and the key components considered in this study?

 

Response 5: Thank you for this observation. The question is relevant since this study covers two important concepts in the framework of solar tracking systems: reliability and maintainability. The reliability index is directly impacted by the lifespan of one or more solar tracker key components. While our study does not assess the reliability of all listed hardware components, we are targeting the Microcontroller’s failure mode via several fault scenarios. This is accomplished via the reconfigurability feature of the main PCB design, allowing us to identify potential errors in the system before these can permanently damage the solar tracking system. The relationship between the failure mode of the system and the microcontroller is analyzed via a set of fault coverage-aware metrics that quantify the number of software and hardware errors in the solar tracker. Conclusively, our research focused on investigating faults that could impact the primary microcontroller and the stepper motors. However, the remaining components of the solar tracking system present opportunities for future research. Expanding the scope to include these additional components will enable a more comprehensive reliability analysis and further enhance the system's robustness and efficiency.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors The manuscript reported on a novel design architecture for more efficient maintenance of solar tracking devices. Comprehensive designs of the hardware and software in the system were presented along with a valuable mathematical analysis. There exist, however, the following issues with the manuscript. The introduction did not adequately explain the advantages that each solar cell technology can benefit from solar tracking. Moreover, photovoltaic solar cells are not the only technology requiring tracking, but concentrated solar power is pertinent to efficient tracking as well. The introduction should clearly illustrate to the reader a thorough rationale of how these technologies benefit from solar tracking to make a strong case for the presented work in the main text of the manuscript and the conclusions. Furthermore, there are minor issues in relation to the font size in several figures being too small to read, while other clarifications have been indicated in the attached pdf. The attached comments should be carefully addressed before the manuscript is further considered.  

 

Comments for author File: Comments.pdf

Author Response

• Please note the schematic does not show where does the cost of tracking and maintenance is embedded. Please indicate in the figure and caption and explain.

 

Response 1: Thank you for pointing this out. We agree with this comment. Figure 1 was modified accordantly to your suggestions, by adding the tracking costs and maintenance costs of automated PV systems.

 

• Several conference proceedings on single and double-axis evaluation were introduced, however, each solar cell technology benefits differently by tracking and this was not sufficiently introduced and supported by peer-reviewed experimental works. How did recent reports on silicon solar cells, see:

https://doi.org/10.1109/JPHOTOV.2021.3126115

https://doi.org/10.1109/JPHOTOV.2013.2282744

https://doi.org/10.1016/j.solmat.2024.112783

and III-V solar cells, see:

https://doi.org/10.1016/j.enconman.2017.11.027

https://doi.org/10.1016/j.enconman.2017.11.024

https://doi.org/10.1016/j.enconman.2017.02.044

benefit from single and double tracking, see

An extended introduction supported by relevant works is suggested.

Response 2: Thank you for pointing this out. We agree with this comment. Therefore, we included the peer-reviewed works in the suggested list in our References. The Introduction Section was completed with additional information regarding various solar cell technologies that could benefit from solar tracking procedures.

 

• PV systems are not the only solar systems that require reliable tracking. Concentrated solar power (CSP) systems require a single axis or double axis depending on the CSP technology. A brief introduction of such systems can strengthen the case for improved solar trackers as presented in the manuscript.

 

Response 3: Thank you for pointing this out. We agree with this comment. Therefore, we introduced the CSP system in the Introduction and Related Work section to support the idea that several PV installations can face major advantages when using tracking methods.

 

• The size of the font is too small to read. Enlarging is suggested.

 

Response 4: Thank you for pointing this out. We agree with this comment. We adjusted the font size in Figure 2 according to your suggestion. If it is necessary, we can further modify the size of the font (for more clarity).

 

• There are letters for each subsystem, however these were not explained. Please add and explain in the figure or its caption.

 

Response 5: Thank you for pointing this out. We agree with this comment. We have added a suitable term for each subsystem letter in the bottom-right corner of Figure 3. All system components can now be easily identified.

 

• The size of the font is too small to read. Enlarging is suggested.

 

Response 6: Thank you for pointing this out. We agree with this comment. Therefore, we resized the font of the text in Figure 4, so that all block components are readable.

 

• The size of the font is too small to read. Enlarging is suggested.

 

Response 7: Thank you for pointing this out. We agree with this comment. Therefore, we resized the font of the text in Figure 4, so that all block components are readable.

 

• An explanation of the change in signal before and after calibration can be added in the figure caption to educate the reader.

 

Response 8: Thank you for pointing this out. We agree with this comment. Therefore, we added a suitable explanation in the Figure 9 caption regarding the calibration of signals. Unfortunately, we were not able to save the experimental data in an editable format, making it difficult to perform changes according to the Hantek Oscilloscope software.

 

• The size of the font is too small to read. Enlarging is suggested.

 

Response 9: Thank you for pointing this out. We agree with this comment. However, similarly to the previous case, the font size could not be changed from the Altium Designer v22 software. The image was exported as a PDF file and cannot be further edited, making it difficult or impossible to resize Figure 12.

 

• Please clarify that the curve is simulated and not experimental as the section title suggests.

 

Response 10: Thank you for pointing this out. We agree with this comment. Therefore, we have specified in the caption that the P-F curve in Figure 13 is simulated and not experimental.

 

• Several designs from the literature can be seen in the table but the performance of the proposed design is missing for a clear comparison. Please explain.

 

Response 11: Thank you for pointing this out. We disagree with this comment. The performance of the solar tracking system designs is presented in Table 1 of the manuscript. Table 3 extends the analysis by highlighting a more careful comparison between the same system designs presented in Table 1 regarding their maintainability.

 

• To reach a wider readership, please consider avoiding acronyms in the conclusions and abstract as well as highlighting the quantitative results of the work.

 

Response 12: Thank you for pointing this out. We agree with this comment. The acronyms were consequently avoided from the Abstract and Conclusions section to reach a wider audience. The quantitative results are clearly described in the Conclusions chapter.

 

• Since there are not only PV systems that can benefit from improved tracking systems, future work on CSP trackers can be suggested.

 

Response 13: Thank you for pointing this out. We agree with this comment. Therefore, we considered CSP systems as a future work research direction, as suggested in the review form.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

My comments are in the attached file.

Comments for author File: Comments.pdf

Author Response

• In the subsequent section, the authors presented “the design of the residential solar tracking prototype, which includes the mechanical structure and components, as well as the electronic equipment that controls the automation steps for optimal PV panel positioning”. This section is quite detailed; I think it is unnecessary to present so much detailed information on this subject.

Response 1: Thank you for pointing this out. We agree with your remark. Consequently, we summarized this section accordingly, while preserving only the details that might be relevant for the reader.

• The next subsection is devoted to Electrical Schematic and Power Management. A table with the list of articles addressing the subject is included in this subsection. But here again, some unnecessary details like “The solar energy provider of the entire sun tracking system, a 100W PV panel (a) from Bruma brand, is located at the bottom part of Figure 3 and includes a 700 mm long cable with an MC4 connector for linking the solar panel to an external storage element” (lines 299-300) are included. Also, the “Connection Diagram and Smart Power Management Solution of the Solar Tracker” (Fig. 3 – line 314) is probably important from a technical point of view. Also, a detailed description of Figure 3 is included in the text. Still, in the case of a scientific paper, a short description of the assumption and the target of such construction is enough.

Response 2: Thank you for pointing this out. We agree with your remark. Consequently, we summarized this section accordingly, while preserving only the details that might be relevant for the reader. Additionally, we removed certain technical details that might not fit the scientific framework of the article.

• Section 4 (line 376), titled “The Software Implementation of the Dual-Axis based Solar Tracking System,” describes in great detail how a modern, automated solar system based on the Internet of Things (IoT) can be designed to minimize the energy consumption of the entire equipment. The authors have included a “Workflow Diagram Custom Functions Used for Automating the Solar Tracking System”. All blocks constituting elements of the functional diagram are described in detail. Again, the description is a little too detailed, in my opinion. The description of the main automation flowchart presented in Figure 5 is very valuable (lines 441 494), however such reference to a subject presented in the previous section, like “all digital pins of the Arduino Mega2560 are assigned to the physical pins of the sensor modules” will lose the reader because he/she will not easily link this description and the previous one, especially since the description of the Arduino Mega2560 was already quite arduous.

Response 3: Thank you for pointing this out. We agree with your remark. Consequently, we summarized this section accordingly, while preserving only the details that might be relevant for the reader.

• Section 5, titled “The Hardware Implementation of the Dual-Axis-based Solar Tracking System,” is easier to understand because some references are included even if something seems difficult to understand. Most of the information presented in this section is related to some data already published in other papers; for example, we can cite Fig. 10. Proposed PRPG Architecture for Test Vector Generation, explained in [52]. The same is true for Figure 11. The proposed RBILBO Architecture for Test Vector Generation and Signature Compression was taken from position [53]. Both [52] and [53] have been written by one or more authors of the submitted paper.

 

Response 4: Thank you for evaluating this section of the paper.

 

Negative Remarks

• Lines 230-231: there is no information about the formulas’ origin.

 

Response 5: Thank you for pointing this out. We agree with your comment. After updating the paper, a reference for the formula in lines 325-326 was included on position [68] (Page 8).

 

• Lines 405-414: the formulas should be better explained (demonstrated), or some references

should be made to their sources.

 

Response 6: Thank you for pointing this out. We agree with your comment. After updating the paper, a reference for the formulas in lines 468-475 was included on position [74] (Page 12).

 

• Line 506: the acronym TPG is starting to be used here without indicating its meaning, then its full development is presented in line 659 (Test Pattern Generator (TPG)).

 

Response 7: Thank you for pointing this out. We agree with your comment. After updating the paper, the term TPG was properly defined on the first appearance in the paper in line 557 (Page 15).

 

• Line 506 again: the authors never explained the meaning of ORA.

 

Response 8: Thank you for pointing this out. We agree with your comment. After updating the paper, the term ORA was properly defined on the first appearance in the paper in line 557 (Page 15).

 

• Lines 678-690: Formulas (6)-(8) are not easy to understand for people who are not familiar

with this type of scientific problem.

 

Response 9: Thank you for pointing this out. We agree with your comment. The formulas in (6) – (8) in lines 727 – 738 now (Pages 20-21) are logic equations written according to basic Boolean algebra. However, we cannot simplify these mathematical relations, since they are directly derived from the hardware architectures presented in the paper.

 

• Formulas and calculus presented in Sections 6 and 7 could be better explained, or some references should be made to their sources.

 

Response 10: Thank you for pointing this out. We agree with your comment. Therefore, we included a proper reference to our previous work on position [77] for comprehending the formulas in a better way (Section 6 – lines 840 – 860). These relations are then further developed and used to compute the fault coverage values as depicted in Section 7.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors significantly improved the manuscript according to the concerns of the review. It is now a more comprehensive body of work with promising cost reduction systems applicable to several research areas and it can now be published.

Author Response

Comments: The authors significantly improved the manuscript according to the concerns of the review. It is now a more comprehensive body of work with promising cost reduction systems applicable to several research areas and it can now be published.

Response: Thank you for pointing this out. We agree with this comment. Therefore, we have made the final changes to the manuscript according to the observations highlighted in the proofreading version of the article. 

Author Response File: Author Response.pdf