Soiling Comparison of Mirror Film and Glass Concentrating Solar Power Reflectors in Southwest Louisiana
Round 1
Reviewer 1 Report
The authors present in this paper a test about the soiling of different solar power reflectors. They compare different reflectors for the climate in Louisiana. The work contains experiments over nearly a year and different evaluations.
The paper has a detailed introduction. However, in chapter 1 are several points missing. What is the new contribution of the paper compared to other studies? Why is this work done, what is the aim? How is the paper structured? These points should belong to an introduction.
On the other side, the theory of the reflector equations could be explained in a second chapter.
- The references in Figure 2 are missing (the same as in table 1, I guess).
- L. 123: What are the design requirements for the specimen?
- You should give equations for the connection of Gloss Units, Soiling Loss etc.
- Figure 4 to 6:
- please provide a constant scaling for the y axis, otherwise the results are hard to compare.
- The color choice could state the difference between thin-film surfaces and glass types.
- A figure with the curve for natural event-cleaned, prewash and cleaned for one exemplary type would be nice, if this might provide any further information.
- Table 2: Is it acceptable to write the numerical values in % or in terms of 10^-3?
- Figure 10: A statistical evaluation would be nice, if these information has a mathematical correlation (not only September)
- Line 267-269: I hope you mean 1-R^2 instead of R^2
In Summary: The paper has an interesting topic, but there is a lot work to be done to improve the paper.
Author Response
Please see the attachment.
Reviewer 2 Report
Dear authors, The paper is relevant for the concept of sustainability in the field solar concentration technologies generally, as it tackles the issue of cleaning, that often relies on the use of water, which one of the major challenges for CSP.
The paper renders a comprehensive analysis of the decrease of reflectivity of mirrors or heliostats in real environment over the time with the use of 6 different types of samples.
General and suggested comments to improve the paper:
- Enlarge Figure 1
- Lines 90-94: could you please recall the main reasons why the SR is dramatically higher for CSP than for PV? Is this because the PVs relies on global radiation while CSP only on DNI? Is this SR linked to the output power eventually?
- Figure 3. It would be useful to legend the samples by adding number from 1 to 6 and give their names in a legend aside
- Figure 3 renders the testbed. How were the cleaning operations were led? Only on a specific portion each of the 6 mirrors on the photograph? Or did you use another testbed with the same kind of mirrors exposed directly outside without any artificial cleaning?
- Line 127: Could you define what is a standard mirror? Basic commercial product bought in a supermarket for instance?
- Line 150: the accuracy of the glossmeter is 2%. Is that true? It looks a high. Could you confirm? Or is this, the angle aperture on the slope of the device (i.e. cone)?
- line 160: maybe it’s more appropriate to give the link in the references rather than in the body text
- Figure 4,5,6: Maybe you could reorder the legend accordingly to the general performance to ease the reading: Dichrotec could be in 5th position for instance. You could use the same consistent order for Figures 7 and 8, so the reader directly understands which samples perform better.
- Line 269: probably the unit is wrong -0.79/d, especially comparing to the values of lines 267-268 which are without units. Please check.
General comments: 1. A picture that shows the glossmeter and the sample during measurements would be an added asset 2. Please comment on what could be expected for the period that is not covered (November to February) in the discussion section.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
Sadly, I can't see the attachment with your answers. Nevertheless, I appreciate your improvements of the paper. Especially, figures 7 and 8 are nice.
The authors adressed the major points of my review (the answer to minor points I can't see). I suggest to accept the paper in the current form.
