Estimating the Potential for Rooftop Generation of Solar Energy in an Urban Context Using High-Resolution Open Access Geospatial Data: A Case Study of the City of Tromsø, Norway
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis paper provides an important contribution towards renewable energies by estimating the potential for solar PV generation via using public LiDAR data.
In order to be able to highlight the importance of this contribution, however, the discussion of previous work does lack the consideration of work on
Quality Assessment of Roof Planes, as performed e.g in the following article:
Simon Schuffert, Thomas Voegtle, Nicholas Tate and Alberto Ramirez.
Quality Assessment of Roof Planes Extracted from Height Data for Solar Energy Systems by the EAGLE Platform.
Remote Sens. 2015, 7(12), 17016-17034
For this reason, I recommend a major revision.
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsI would like to thank the authors for their study and proposed methodology to assess the rooftop photovoltaic (PV) potential at city scale. This is a complicated task as shown in other publications in the scientific bibliography on the same topic, not only derived from the input data required but also from the simulation perspective. It is especially interesting the consideration of a location at such high latitude, since as stated by the authors, these locations are often disregarded for solar energy applications, especially PV. I strongly believe that studies like the one presented in the manuscript entitled “Estimating the potential for rooftop generation of solar energy in an urban context using high-resolution open access geospatial data: a case study of the city of Tromsø, Norway” could help policy makers, governments and final users to identify and estimate the PV potential of available rooftops and to further promote the deployment of solar PV energy in urban environments.
The objective and application of this study is fully aligned with the European Union’s Solar Rooftop Standard which is part of the Energy Performance of Building Directive and it could be clearly stated in the manuscript as it could promote the extension to other regions in Europe.
After reading the manuscript I would recommend it for publication with minor revisions as I believe there is room for improvement. The suggested changes, corrections and comments aim at clarifying various points in order to help future readers wanting to replicate this study in other locations, or to compare the results from this study with other studies and methodologies focused on the estimation of the rooftop PV potential in other regions, especially with similar spatial coverage, city level.
My comments and suggestions are detailed in the following.
Abstract.
Please consider adding in the abstract more details about the study and the results obtained. For example, about the city analysed (information like area, population, latitude or number of buildings considered) and the results. Instead of “significant fraction of its electricity demand” it would be better to specify a number.
Introduction.
Please clarify if you are talking about solar PV energy or solar energy in general.
L34: similarly, replace “dedicated arrays” by “dedicated PV arrays” and “rooftop generation” by “rooftop PV generation”.
As mentioned in lines 41 to 42, another benefit of rooftop PV installations is the reduction of the competition for land of the PV deployment with other uses such as agriculture as they use area already available for the installation of PV.
Including references to European Directives for the further deployment of PV installations in urban environments, using rooftop areas, would be beneficial and would support the impact and relevance of the study.
L67: “Arc-tic” by “Artic”
L68: “in-creased solar radiation” by “increased received or in-plane solar radiation”
L97: PVGIS has been developed by the European Commission. Furthermore, this online tool provides data directly to the user so the sentence in lines 99 and 100 does not really apply to PVGIS since the user does not need to apply any computation and data is provided almost instantly. Please rewrite.
L100: define DSM
L114, L199 and L357. Please unify the way citywide is written.
L128: “it also can also” by “it can also”
Materials and Methods.
L151: “south-facing roofs These”. Full stop missing
L151: which tilt has been considered for the estimation of the annual energy generation? Or are these numbers relative to an horizontal plane? Which type of PV module has been considered, efficiency?
Footer of Figure 1. Include a description to both Figure 1a and 1b.
L 249: define DTM
Footer of Figure 2. The discontinuity is due to a change in the irradiance data, not the meteorological one. Please correct. SARAH2 data below that latitude threshold and ERA5 for locations with higher latitude.
More information on how to estimate E0 is necessary in order for readers to replicate this study and apply it in other locations.
Factor f uses only horizontal plane, while this ratio is directly applied to the estimation of tilted planes. Does this direct application depend on locations with predominant clear skies or predominant overcast skies. Furthermore, a fixed value of 0.4 is applied to the whole city.
Instead of the factor f PVGIS-SARAH2 could have been used to extract for every location the relationship between the yearly irradiation at any tilted plane and the horizontal one.
The fact that local shadows and horizon have not been considered is a weak point of the proposed methodology since these elements could have an important impact on the PV potential in urban environments. Has this effect been analysed for any specific building in the study area? Authors have indicated in the Discussion that these effects could be considered in the future using a statistical approach.
How does the method to define suitable and unsuitable rooftop areas compare with real values or real buildings and other studies that apply a fixed number, like 25%.
The method to estimate the annual yearly irradiation and PV generation should be better described. How have equations 4 to 7 been obtained? Based on which values?
Results
L302&L311: “Figures 4a,b” like in L 290
Figures 4 and 5. Which area is considered in the generation potential? The horizontal plane or the tilted roof and PV modules?
The European Building Footprint database could be useful to characterise every type of building.
Have authors tried to plot Figure 6 with orientation? What is the average orientation so as to add this variable to Table 1?
Information about the supplementary materials is missing.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper presents the methods and results of a case study using public available datasets for estimating the solar enginery potential of generating electricity in the city of Tromso, Norway. It's not of high scientific value but should be interest to IJGI journals due to its study of high-latitude urban environments.
Overall, the paper is well-written and structured. I would suggest authors considering the following in revising the paper before considering for publication:
1. Elaborate how the known models and tools are relatively computationally intensive and processing times for a large DSM can be long, in case of just considering rooftop surface (slope, orientation & surface area?) without shading or other factors. In otherwise, have authors tried existing models and tools for this case study?
2. What and how are the publicly available ultra-high resolution LiDAR data processed to obtain what are needed for the simplified method?
3. How were the final results verified? Unless I have missed, I don't see discussions on the validation of results. Are the numbers correct or close to correct, for example in comparison with the results from Point #2, if tried?
4. If shading is to be considered as suggested in Authors' discussions, will the method be substantially changed or will it maintain current simplicity and transparency?
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsDear authors,
The article is very interesting and relevant as it explores solar energy generation in urban environments using high-resolution open-access geospatial data. Its focus on the city of Tromsø, Norway, provides a valuable case study for assessing rooftop generation potential, particularly in regions with adverse climates.
Before publishing, a few brief recommendations:
The introduction should clearly present the structure of the paper.
In the materials and methods section, it is important to explain the scientific methodology used beforehand, ensuring that it can be applied to other regions.
The abstract should include both qualitative and quantitative results to provide a comprehensive view of the study.
Have any limitations been identified in the article?
What potential research directions could be developed in the future based on this study?
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe new version now is in an acceptable form as it now addresses the issues raised in my previous review. Recommendation: accept as is.
