The harmony and look of solar panels is one of the important topics which is a matter of a wider debate by researchers, PV module producers, and finally end users [1,2]. The solar panel’s aesthetic issue is related to how they look with the rest of the installation environment (rooftop or solar farm). It is all about the harmony between the visual look of the panels and its surroundings.
Here, the problem can be divided to using solar panels as building material, or in a large scale solar farm. The “sight defect” and social acceptance of solar panel deployment in large-scale projects like solar farms and solar parks is a quite different issue which is out of our scope here. This article will focus on the natural beauty and harmony of solar panels as a construction material or accessory for buildings.
Solar Panels as Building Material, BIPV / BAPV
Newly solar panels are regarded as a construction material and they are responsible for supplying partly or completely the amount of energy demand of buildings [3,4]. In this regard, solar panels are integrated in buildings as a construction material and referred to as building integrated photovoltaics (BIPV). Different types of solar harvesting devices including tiles, foils, and solar panels are assembled to reach this goal . Although solar panels have higher efficiency and power output compared to solar tiles and foils, there is a poor harmony with other parts of building, especially rooftops.
On the other hand, when solar panels are used as an accessory for existing old buildings the aesthetic aspect of it becomes more crucial than before. This type of mounting solar panels on buildings is known as building applied photovoltaics (BAPV) .
Problems in hand
Now that we went through the BIPV and BAPV concept, it is time to mention what are the actual problems that create an aesthetic issue and spoil the harmonic relationship between the solar panels as building materials and the rest of the structure. Let’s dive into more details and the technological response to these issues.
Some PV module producers, to address and promote the aesthetic quality of solar panels for both BIPV and BAPV, have released PV modules with white encapsulants or black backsheets [6-8]. It is important to notice that all conventional solar panels consist of 5 layers, including glass, front encapsulant layer, matrix-cell/solar cells, rear encapsulant layer, and backsheet. Both encapsulant layers and backsheet not only have the responsibility for the protection of solar panels from harsh environmental conditions but also have an impact on the aesthetic aspect.
Visible Fingers & Busbars
It is important to notice that nowadays by emerging new high-efficiency technologies at the cell- and module-level such as interdigitated back contacts (IBC) and shingle solar panels, PV module producers have implemented these technologies to remove fingers and busbars from the front side of the panel and entirely from both sides of it respectively. In this direction, due to the black appearance of monocrystalline solar cells and removed solar cell connections in these technologies, utilizing black backsheet is more prevalent than white encapsulant owing to end user’s preference and consequently PV module producers’ priority.
All in all
It is worth mentioning that solar panels with black backsheets lead to the aesthetic enhancement, however, they have lower optical gain at the cell- and module level. Because black color is a better absorbent of light rays while white encapsulant is a better reflector. Therefore solar panels with white encapsulants have better optical gains than those with black backsheets . Moreover, to some extent this optical loss mitigates with high efficiency of solar cells with IBC or Shingle techs. Assessing the optical gains and losses at the solar cell level or module level are studied by evaluating the cell-to module ratio or CTM ratio [7,9].
Finally, It is crucial to know that rooftop solar installation is one the main pillars of decentralized power generation by solar power and promoting the aesthetic aspect and public awareness can result in higher penetration and public acceptance from social and environmental sides as well.
Author: Shahab Moghadam
 Zomer, C. D., Costa, M. R., Nobre, A., & Rüther, R. (2013). Performance compromises of building-integrated and building-applied photovoltaics (BIPV and BAPV) in Brazilian airports. Energy and buildings, 66, 607-615.
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 Solaria All-Black edition
 Saw, M. H., Khoo, Y. S., Singh, J. P., & Wang, Y. (2017). Cell-to-module optical loss/gain analysis for various photovoltaic module materials through systematic characterization. Japanese Journal of Applied Physics, 56(8S2), 08MD03.
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