Solar Potential in Saudi Arabia for Southward-Inclined Flat-Plate Surfaces

Round 1

Reviewer 1 Report

Overall the manuscript contains worthwhile information and adds important information to existing knowledge. However, I am not really happy with the description of the work and the scientific soundness. I think a major revision is needed to improve the manuscript. Please see my comments for further details.

 

Line 50-51

“Other methods use a combination of ground-based solar data and modelling [e.g., 2] or utilise solar data from international data bases [e.g., 18] or even combine satellite-derived solar data with modelling [e.g., 19].”

As in your study a main source of information are satellite based data sets, this should be mentioned more clearly, in addition or even sounds a bit weird…Please rephrase

 

Line 69-70

“From the above it is clear that no attempt has been made so far to construct a solar map for Saudi Arabia to show the potential of flat planes inclined southwards for the exploitation of solar energy by appropriate systems”

I think that PVGIS made attempts, but EC is probably not allowed to publish them for Saudi Arabia, please discuss.

 

Line 72-76 and 367-372

“For the first time….

“For the first time…

“For the first time worldwide, the notion of the correction factor is introduced and universal curves (nomographs).

And Line 269-270

“In other words, CF corrects the energy on an inclined surface under the influence of a ground albedo equal to 0.2 to that which is under the influence of near-real ground-albedo value.”

It is quite difficult to be aware of all publications coming out, there are simply too much. Thus, I would be very careful with such claims. E.g. the use of a SAL correction factor is not really new, see (e.g. Remote Sens. 2012, 4(3), 622-647; https://doi.org/10.3390/rs4030622) However, in your work it is done for various tilt angles, adding new aspects. Overall the above statements are too general and misleading. Please rephrase. The authors are not aware of …. and please be more precise concerning the novel aspects

 

Line 86

PVGIS offers also other data sources, please discuss the reason why the other sources has not been used. Please also add a citation for SARAH data.

 

Line 132-134

“The parameters Rdi and Rr are called the isotropic sky-configuration and ground-inclined plane-configuration factors, respectively. In the Liu-Jordan model the ground albedo usually takes the value of ρg0 = 0.2. This value has been used in the present study. Apart from that, values of ρg near to reality were also adopted here. To retrieve such values for the 82 sites, use of the Giovanni portal [34] was made”

Not really clear how ground albedo is dealt with. When is 0.2 used and when values near to reality are used. Please add also some more information on the source of the surfaces albedo data.

Further, the used PVGIS solar radiation data set considers SAL as well. Here surface albedo (SAL) from a different source is used for the correction factor: This means that SAL values with do not equal 0.2 are somehow corrected twice. This could lead to misleading results, please clarify and discuss.

 

Section 3.4 Maps of Annual Energy Sums

I think there is a need to discuss the results in more detail. E.g. why is the solar radiation so low in the North-East. Please discuss the meteorological phenomena that leads to the large spatial gradients in the map/date.

 

3.5. Evaluation of the PV-GIS Tool

I think 1 station relative far away is not sufficient for an evaluation. Please use at leastthe data from the BSRN station Sede Boqer in addition. https://bsrn.awi.de/products/quality-code/physically-possible-limits/sede-boqer-sbo/

Also neighbouring countries measure solar surface radiation, e.g. Iran, however it might be that they are not accessible. Please check and discuss.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Studying the inclination of panels is not innovative. Doing it for Saudi Arabia is a straightforward exercise. However, a new version may be submitted considering the following:

• Listing of sites in Table 1 and Table 2 is useless. Figure 1 and 2 are sufficient.
• Presentation of tables 3 & 4 can be improved by putting the equation the same line
• Energy needs in the sites should be discussed as well as how solar can meet these needs.
• A conclusive methodology should be proposed on the basis of the presented work.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Dear Authors,

Thank you very much for submitting your manuscript to this Journal. As per the editorial guidelines, this manuscript has been reviewed with intensive care. This paper has written well and it useful for the readers (i.e., academia and industrial engineers/ practitioners). However, there are several issues need to clarify before proceed to publications. These are listed as follows:

1) The present form of the abstract is a bit week not much clear, I recommend to re-write it with 2/3 stronger sentences about your objectives/ findings that will give a better understanding for the readers.

2) All the Figures x- and y- axis need to write correctly, especially Fig. 9 - 12. Some of the axis's are not clear as mentioned only the symbol.  The linewidths/ boarders are very low, need to correct it for good visibility. 

3) The current form of the conclusion is long, I recommend to re-write the conclusion with good summary with stronger sentences that you have achieved from this research. That is your findings that will give an easy understanding for the readers. 

4) The references are 36 but it is recommended to add more suitable references from other published works. You can add some useful references from Edith Cowan Univ./ Curtin University/ USQ/ CQUniversity/ Monash University Research Group as they have done significant works on Solar and PV systems, and published in Journal articles as well as conference presentations. Such as, Das et al., Islam et al., Nazme et al., Zang et al, Jithin et al., Premaratne et al., and others too.

5) There are several typos and grammatical issues in the manuscript. Please clarify it carefully before proceed to publications.

6) Finally, I recommend to demonstrate in brief about the impact or significance of your research in the industry and community. 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear authors,

 

thank you for the revision. The manuscript has been improved, but some  items are still open.

 

Q1.1  Still open.

"In the case that none of these alternatives is possible, satellite-derived solar data can be used instead 55 and be combined with modelling [e.g., 24]. "

I apologize, but in my opinion your answer is now even more misleading. Please note the primary PVGIS radiation source (SARAH) is based on radiation retrieved from satellites. Your are using SARAH as well. Satellites are the primary source of Information in many regions of the world and are also frequently  used in regions with a dense network of well maintained ground based stations (e.g. improvement of gridded data sets, Quality Control of ground based measurements )

 

Q1.2 Still open

Please note that was a misunderstanding I referred to the PVGIS maps at

https://re.jrc.ec.europa.eu/pvg_download/map_index.html

Here, Saudi Arabia is missing. Please discuss.

 

Q 1. 3 Still open

You are still using for the first time in combination with worldwide. I guess you have not read all papers from China, so how will you know . Please add "to the Knowledge of the authors..."

 

Q1.5 Still open. Please  mention in more detail what is covered by apart from.

"In the Liu-Jordan model the ground albedo usually takes the value of ρg0 = 0.2. This value has been used in the present study. Apart from that, values of ρg near to reality were also adopted here"

 

Q 1.6:  Still open

Also the horizontal irradiance is affected by SAL. The higher the SAL the higher the solar surface irradiance (horizonal plane ) for otherwise identical conditions. Please clarify that a different source for SAL was used für SARAH than for the study and that this might induce minor uncertainties in your results.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Authors clarified the issues, comments and recommendations.

No more comments.

Minor English need to be corrected during the galley proof. 

Author Response

We thank you for the approval of the corrections provided by your comments. The few English language problems will be corrected during the galley-proof process.