Effects of Reflectance of Backsheets and Spacing between Cells on Photovoltaic Modules

Abstract

In the photovoltaic (PV) module manufacturing process, cell-to-module (CTM) loss is inevitably caused by the optical loss, and it generally leads to the output power loss of about 2~3%. It is known that the CTM loss rate can be reduced by increasing the reflectance of a backsheet and reflective area through widening spaces between the PV cell strings. In this study, multi-busbars (MBB) and shingled PV cells were connected in series, and a mini-module composed of four cells was fabricated with a white and black backsheet to investigate the effects of reflectance of backsheets and space between the PV cells. Moreover, the MBB modules with cell gap spaces of 0.5 mm, 1.5 mm, and 2.5 mm were demonstrated with fixed 3 mm spaces between the strings. The shingled modules with varying spaces from 2 mm to 6 mm were also tested, and our results show that spacing between PV cells and strings should be well-balanced to minimize the CTM loss to maximize the output power (efficiency).

Impact of the infrared properties of the backsheet on the efficiency of an encapsulated photovoltaic silicon cell

“…White is the most widely used color for backsheets, whereas black backsheets are frequently encountered for aesthetic purposes [3]. According to research [4], optimizing the gap between cells and using white backsheets lead to 1 to 2% of improvement in the maximal power compared with the usage of black ones. Luxembourg et al demonstrated that the application of black powder coatings with low IR absorption on standard films used in the photovoltaic industry can significantly reduce cell-to-module (CtM) losses for all the black modules [5].…”

Laser-Induced Backward Transfer of Light Reflecting Zinc Patterns on Glass for High Performance Photovoltaic Modules

“…In earlier module designs, the gap between cells ranged from 2.5 to 3 mm, but in modern commercial PV modules, this gap has been reduced to approximately 1.5 to 2 mm. A 2 mm gap is the most typical [1][2][3].…”

Optimized White Laminate and Redirecting Film as Back Reflectors for High-Efficiency Monofacial and Bifacial Photovoltaic Modules

“…8 Researchers have extensively implemented metal surface made of aluminum or silver, 9 different textured substrates and white laminates as suitable BR designs for boosting the photocurrent, such as white paint coatings, 10,11 periodic structures, [12][13][14] plasmonic nanostructures, 15 random texures 16 and white backsheets. 17,18 White backsheets and metal coated structures have been commonly employed in the industry since white backsheet could guide more than half of the light while metal coated structures guided nearly 75% of light hitting inactive areas onto the cells, thereby increasing the conversion efficiency of PV modules by around 1%. 19 Apart from the reflectance of BR, the space between cells resulting into passive area (inactive area) losses on the PV module is also another crucial factor in influencing energy efficiency.…”

“…19 Apart from the reflectance of BR, the space between cells resulting into passive area (inactive area) losses on the PV module is also another crucial factor in influencing energy efficiency. 20,21 It has been reported that reducing the space between cells would decrease the solar light reflected by backsheets. 22 Z. Liu etc.…”

“…20,21 It has been reported that reducing the space between cells would decrease the solar light reflected by backsheets. 22 Z. Liu etc. extracted the light harvesting efficiency of two different backsheets (white backsheet and a scattering tape) and of metal fingers in one-cell mini-modules.…”