Lookup Tables for Power Generation Performance of Photovoltaic Systems Covering 40 Geographic Locations (Wilayats) in the Sultanate of Oman, with and without Solar Tracking, and General Perspectives about Solar Irradiation
Round 1
Reviewer 1 Report
The article presents a methodology for obtaining easy-to-use loookup tables to assist professionals in planning and designing PV solar plants in the Sultanate of Oman. The lookup tables are meant to be used as a replacement for more complicated simulation tools or mathematical equations. The methodology is not country-specific and can be generalized.
Publicly available data and simulation tool (Photovoltaic Geographical Information System - PVGIS by EU's JRC) are used to obtain the yearly PV electricity prodction per installed kWp of crystalline silicon (c-Si) PV modules, and the yearly global solar irradiation received per m2 of tilted PV panel surface, at given second-level administrative divisions (wilayats). Out of the 61 wilayats, 40 are chosen for the analysis, with a minimum representation of each of the 11 first-level governorates.
The tables are built by running simulations for each wilayat with the PVGIS tool. Three tables are obtained, one for each type of PV installation: fixed-mounted (free standing) with optimal orientation (slope and azimuth angles), single-vertical-axis solar tracking and two-axis solar tracking.
Each table contains the yearly PV electricity production per kWp installed, the yearly global solar irradiation received per m2 of tilted PV panel surface, the optimized azimuth (for the fixed-mounted configuration), the optimized slope (for both fixed-mounted and single-vertical-axis solar tracking) and scaling constants that translate the values of PV electricity production from a location to the capital (Muscat) and vice-versa.
The results were validated with another publicly available tool, the Global Solar Atlas by the World Bank Group. The validation shows consistency in the obtained results, with negligible discrepancies.
The article is overall well written, and it achieves its purpose of obtaining a simple tool (the lookup tables) for usage by personnel which is not trained in the usage of complex simulation tools and mathematical equations.
The discussion of the results is long-winded, in particular the description of the (Translation Factors) would benefit from a more concise explanation (lines 376-424).
Moreover, in tables B1, B2, and B3, the "Yearly PV electricity production per kWp installed [kWh/kWp/year]" column is redundant if the columns "Translation Factor1 (X to Muscat) for yearly PV electricity production" and "Translation Factor2 (Muscat to X)" were to be included: the so-called translation factors are not necessary when the PV electricity production of each location is already enlisted in the same table. I suggest to specify the reference quantity (in this case Muscat's yearly PV electricity production per kWp installed) on its own and just include the translation factors. Translation Factor2 (Muscat to X) could also be omitted, as it is the reciprocal of Translation Factor1, and an equation could be included to showcase the process to convert the expected electricity generation from one location to another. As a result, tables B1, B2, and B3 could be merged.
Author Response
The reviewer's effort is acknowledged.
The paper was revised. Please see attached response.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The tables attached to the article provide a valuable tool for society and energy planners seeking to install PV panels as it provides expected output as well as the optimal tilt of installed panels for specific locations in the sultanate of Oman. The methodology is sound and input as well as output data can be openly used.
However, the additional use for appliers of the results compared to other publications is not evident. There are two easy to use platforms which openly provide the same information. https://globalsolaratlas.info provides a word solar map, indicating information on irradiation and optimal tilt of PV modules. https://www.renewables.ninja/ provides the possibility to download time series of renewable power generation, including different technologies of PV modules. Therefore, the novelty of the present work is not evident. Without clarification of the novelty the work is not recommended to be published.
Author Response
The reviewer's effort is acknowledged.
The paper was revised. Please see attached response.
Author Response File: Author Response.pdf
Reviewer 3 Report
small improvement 19 - should be small (cca. 5%) improvement (with numbers)
Research is limited to Oman, however situation in Oman should be compared to different regions in world (eg. Mexico - same latitude or recently published data for Romania and Turkey / mdpi journals).
345 ... (in kWh of alternating-current electricity for 1 kWp of installed photovoltaic capacity and over one year
should be
(in kWh of electric energy for 1 kWp of installed photovoltaic power and over one year)
I would not put Figure 3 in this paper, that is more for conference papers.
This is conference paper, it is lot of work but I cant find scientific contribution. Scientific contribution would be to predict data and after that to confirm that prediction by measurement.
Author Response
The reviewer's effort is acknowledged.
The paper was revised. Please see attached response.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The article in the present form is more concise and was completed by comparing the results with real measurements in Adam, and performing an analogous analysis on 12 different locations, with comparable distance from the equator than the Sultanate of Oman.
Figure 3: the scale in degrees should be edited as it is not clear. It could be overlapped with the plot itself.
Line 418: it should be 2013.
Line 443: "latitude" in place of "longitude"
Figures 9, 10: I recommend to align the bars to either left or right-hand side to make the differences more evident.
Author Response
The reviewer's effort is acknowledged.
The paper was revised for the second time. Please see attached response.
Reviewer 2 Report
The newly added section has greatly improved the article. It highlights the novelty of the work which was the major flaw of the previous version and puts it into a global context, thus implying relevance for a greater audience.
A few minor changes are suggested:
- Figure 1 : Add markers to Thumrait and Madha for consistency with Muscat and Adam
- Figure 3: If possible, I recommend placing the angles directly into the figure, not above it, as in the current format it is not clear whether 0° is the innermost or outermost circle
- Line 418: it should be 2013 not 20113
- Line 443: it should be latitude, not longitude.
- In the second part of the new section, sometimes 11, sometimes 12 new locations outside of Oman are mentioned. It seems this should be 12 everywhere.
After these minor adjustments the article is recommended for publication.
Author Response
The reviewer's effort is acknowledged.
The paper was revised for the second time. Please see attached response.
Author Response File: Author Response.pdf
Reviewer 3 Report
Tis is conference paper. Editor should decide to accept it or not.
Author Response
The reviewer's effort is acknowledged.
The paper was revised for the second time. Please see attached response.
Author Response File: Author Response.pdf
