Future Options for Lightweight Photovoltaic Modules in Electrical Passenger Cars

Round 1

Reviewer 1 Report

I recommend the publication of this revised version to the journal of Sustainability.

Author Response

Thank you for your kindly response

Reviewer 2 Report

Dear Authors,

Thank you for improvements of the manuscript. However, the presentation should be improved. The type of paper is not specified at the top of the first page in the manuscript. It is assumed to be a review. The abstract should be a single paragraph according to instruction for authors from Sustainability journal site. Vehicle-integrated photovoltaics represent one of the most promising way to achieve a low-carbon mobility in the future. I encourage the authors to provide more results obtained by other researchers in applying lightweight photovoltaic modules into the electrical cars. Thus, this paper would be more valuable.

Author Response

This paper is review paper and the abstract revised to 1 paragraph.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript has not changed significantly in comparison to the previous version. Although, the minor mistakes have been corrected according to my previous comments. The main problem of the paper (lack of research in the field – no methodology, no measurements, no data, no research) is left unchanged. In my opinion in the present form the manuscript is not a scientific paper but a kind of concept of the Authors which still has to be proved (by a precise measurements). For this reason  I regret to not recommend the manuscript for publication.  

Author Response

The lack of experimental data is because this paper is a review paper on vehicle weight reduction. This is a matter that must be developed in order to supply solar power generation in countries with small land area like Korea.

Point 1: The manuscript has not changed significantly in comparison to the previous version. Although, the minor mistakes have been corrected according to my previous comments. The main problem of the paper (lack of research in the field – no methodology, no measurements, no data, no research) is left unchanged. In my opinion in the present form the manuscript is not a scientific paper but a kind of concept of the Authors which still has to be proved (by a precise measurements). For this reason  I regret to not recommend the manuscript for publication..


Response 1:

Dear Reviewer

We are appreciating to the reviewer’s point. Please note that this paper is not a research paper discussed with experimental data.

To meet the carbon-neutral society, renewable energies such as solar photovoltaics and wind must be massively employed. However, countries such as Korea, which have a small area of land and high population density, have difficulty installing large area photovoltaic plants. Therefore, a new kind of photovoltaic application such as vehicle-integrated photovoltaic (VIPV) or Building-integrated photovoltaics (BIPV) would be a meaningful choice.

Here, in this manuscript, a review was conducted on vehicle weight reduction for effective application. Data-based content is lacking, but it is an essential aspect of VIPV application.

Round 2

Reviewer 3 Report

The Authors have addressed my doubts pointed out in the review. Some minor corrections have been listed below.

Line 39-40: Something is wrong in this line (probably should be without ‘such as’)

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The manuscript deals with the basics concepts of using relatively light photovoltaic modules in comparison to typical silicon-based ones for electric car applications. The main idea is interesting and worthy of investigation. However, the manuscript does not present any research data, results, or analyses which are mandatory for scientific papers. The manuscript is rather a description of the Author’s conception than a scientific paper (or research). For this reason, I cannot recommend the manuscript for publication in Sustainability. Some more concerns below...

• 75-76: “When charging for 5h, the maximum amount of power that can be obtained by using the module during a day is 1 kWh” – pay attention that unit kWh means energy, not power! Moreover, the energy production from the PV module depends on many factors, i.e. location (latitude), temperature of the module, tilt angle, shading (in the cities)..
• Figure 2: Efficiencies of the modules mentioned in lines 185 – 187 are closer to 20-25 % than 40 %!.
• “to install 800 W … the area of roof and hood is approximately 2.5 m²” – this is not true. Based on Fraunhofer PV Report, the Authors can find the record efficiencies of different kinds of PV modules (silicon-based, thin-film, and Perovskite). Assuming efficiencies mentioned in the Report, a surface area is much higher than 2.5 m² (3,7 m² for Si and almost 5 m² for Perovskite)
• “the side of the vehicle” – the tilt in this case is non-optimal. It should be discussed in the text.
• “this study investigated solar modules suitable for electric passenger cars” – there is no evidence of the research in this field: no data, no measurements, etc..

Reviewer 2 Report

Journal: Sustainability

Manuscript Number: Sustainability -1052147

Title: Future Options for Lightweight Photovoltaic Modules in Electrical Passenger Cars

Type of manuscript: Review

Recommendation: Major revision

1. The subject of the manuscript falls within the topics of the journal.
2. The type of paper is not specified in the manuscript. It is assumed to be a review according to information from review report form link.
3. The presentation of the study needs to be improved. The authors should do more efforts in presenting more in-depth information.
4. The manuscript is well written but needs to be thoroughly edited. The use of English needs to be checked and the manuscript revised.

Title

The title seems not really match to what is presented in the article. The authors pretend to present future options, but it is not clear if the information is processed by them from other articles or it is simply taken and presented.

Abstract

The abstract needs to be rewritten. Its length (233 words) exceeds the 200 words maximum limit and, at the same time, it should be a single paragraph according to instruction for authors from Sustainability journal site.

Keywords

(VIPV) vehicle integrated photovoltaics abbreviation should be defined before, in abstract.

1. Introduction

Line 47-48 – “…an electric vehicle takes up to 30 min to recharge [4]” – the authors should reformulate because empty-to-full time to charge most electric cars is longer than 30 minutes even when a rapid charger is used.

Line 71-72 – The bibliographic sources for Figure 1 are missing.

The authors could provide information regarding photovoltaic mounted solar roof cars not only from the Sonata model of Hyundai Motors or the Toyota Prius model, but also other cars, for example the Lightyear One model.

2. Effects of applying solar modules to passenger cars

Line 87 – “In Germany, 80% of people drive less than 54 km, and 50% drive 27 km [8].” – I think the authors wanted to specify that German drivers drive that mileage on average in one day.

Line 93-94 – “The weight of the panoramic sunroof used on the roof of a passenger car is 60–80 kg, and the solar module used for the Prius is approximately 30 kg.” – the bibliographic sources are missing.

The authors should do more efforts in presenting more information in this paragraph.

3. Methods of reducing the weight of solar modules for passenger cars

Line 104-105 – The bibliographic sources for Figure 3 are missing.

            The authors should present the estimated costs for each proposed solution. The potential materials used for photovoltaic cell production should be detailed.

4. Conclusions

The presentation of the conclusions should be improved.

Reviewer 3 Report

In the manuscript titled “Future Options for Lightweight Photovoltaic Modules in Electrical Passenger Cars”, the authors discuss the solar modules suitable for electric passenger cars, and propose the possible approach and structures to reduce the weight of solar modules to improve the fuel economy of an electric vehicle. This study provides some promising perspectives to apply lightweight photovoltaic modules into the electrical cars. I recommend the publication of this paper to the journal of Sustainability after some minor revision. Detailed comments and questions are as following,

1. In Line 87, 88, 89 on Page 3, the authors mentioned “When the fuel efficiency of the car is improved, and it reaches 10 km/kWh, it is possible to drive only by parking at 20 km when it is said that 4 h can be fully charged with a module of approximately 500 W.” How is this conclusion derived? More discussion may be needed.
2. In Line 104 on Page 3, the equation for curved factor is wrong as 45.01W is used both in the numerator and denominator.
3. In Line 119, 120 on Page 4, the authors mentioned “PMMA and PC have a density twice that of glass,…”. However, the density of PMMA and PC is half of that of glass.
4. In Conclusions on Page 6, the authors mentioned “The panoramic sunroof weighs approximately 70 kg, the commercial silicon-based 200 W module weighs 20 kg, and the lightweight model weighs 10 kg. The weight of the photovoltaic module applied to the Prius model is 30 kg.” What is the purpose giving those numbers for different weights? The key points should be provide regarding these values.