Solar module has seen immense developments in power output, efficiency, interconnection, etc. in the recent years.However the heavy weight of solar panel primitively due to the glass and Aluminium frame (used in it) limited its use on many roofs. Replacing these materials was a tough as it challenged the reliability, ruggedness and aesthetic appeal of a PV module. This is when flexible (and frameless) modules came into picture. As the name suggest flexible modules are those which can (almost) be installed on any shape and/or size of mounting surface. These modules tend to fulfil almost all the customizable requirement. With the world adding almost more than 200 GW of solar PV modules in the next 5 years, it is estimated that the share of flexible modules in such capacity addition would be around 3 to 5%. One reason that can be attributed to this is the widespread adaptation of PV modules and increased energy demand of consumer. This quantifies the usage of solar PV flexible modules for many customized applications (such as on car sheds/ports, transportations, remote mobile applications, residential roofs with special conditions). Merlin (Figure 1)is one of its kind flexible modules available in the market. While there has been a lot of buzz in the market, very less is actually known about the module. This blog hence aims to educate its readers on the technical aspects and advantages of using Merlin modules.
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Figure 1: A typical flexible solar module (Source: Team Merlin, Waaree Energies) |
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Conventional solar cells have fingers and busbarswhich are used for current collection. The cells in Merlinmodule use patented manufacturing process &design (7 patents in US with 53 total patents pending worldwide)to encapsulate its cells. Known as the “grid” (as evident from Figure 2), the mesh type front grid has 20 busbars which are optimally designed to ensure maximum light falls on the solar cells. Overall the entire grid has around 1,200 current collection points which are way more than the normal solar cell. These busbars in the front grid are interconnected with each other. This enables that the current is collected efficiently even in case of micro crack or a crack in the solar cell.The rear grid in Merlin cell in addition to carrier collection, also ensures that the entire assembly is held together (without damaging the solar cell) when bent giving the module its flexible nature (to an extent).The grid uses almost half the silver while comparing it to the normal busbar cell. Additionally, the extension of front grid (circled in red in Figure 1) is used as an interconnect between the cells.Hence, utilizes maximum possible area in a module.
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Figure 2: Difference between Merlin (left) and conventional (right) solar cells |
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The next and the most important property of Merlin module is its reliability. The flexible module has been tested under various conditions, climates & orientations and in all the tests, they have been found to operate at a level much above the normal. One of the test was to test the flexibility of the Merlin grid and cell. For this, a module was made and bent as shown in Figure 3 (left). The Electro Luminance (EL) image and power output before and after the test was recordedFigure 3 (right). As expected, the module was found to be perfectly intact and there was almost no loss in power output even after extended testing.
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Figure 3: Flexibility test of Merlin module (left) and EL image of the module (right) Figure 3: Flexibility test of Merlin module (left) and EL image of the module (right) |
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The figures below compares the testing result of Merlin module to the primitive modules. Figure 4 shows the test result of 1500 Pa mechanical loading test subsequently followed by humidity freeze test. Figure 5 shows the test result of transportation test where modules were mounted on a transport vehicle for a specified distance. Figure 6 shows the test result of thermal cycling after 1,000 cycles. It was found that the Merlin module almost out performs the standard module in almost all the standard tests depicting the rugged nature of Merlin modules.
Figure 4: Modules subjected to 1500 Pa load test and Humidity Freeze test (Source: Team Merlin, Waaree Energies)
Figure 5: Modules subjected to Transportation test (Source: Team Merlin, Waaree Energies)
Figure 6: Modules subjected to Thermal Cycle test (Source: Team Merlin, Waaree Energies)
The conventional solar module (normally) comes in two standard offering i.e. 60 cell and 72 cell which has cell configuration of 10x 6 cell & 12 x 6 cell. The size of these modules is(approximately) 1650 mm x 990 mm & 1960 mm x 990 mm respectively. The merlin modules on the other hand could be made up with any number of cells depending on customer’s power requirement. The cells in this module can also be arranged according to the requirement and space availably of the end consumer i.e. say a module of 24 cells can be made by 4 x 6 cell or 6 x 4 cell or even in 12 x 2 cell configuration.Such customized panels are of use mainly in northern and western countries where (specifically 2 x 12 & 2 x 10) modules fit exactly into the size of their roof without compromising the roof’s purpose (to allow easy drifting of snow during winter).
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Figure 7: Different possible sizes in Merlin module |
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The Figure 8 below depicts (few of) the various configurations available for a typical PV plant.Installing such power plant requires a lot of steps such as levelling the rooftop ground, drilling, digging, piling, bolting, welding, etc. before the solar modules are actually installed. This process may take about 1~3 months of time and its equivalent man-hours & adequate capital before the power plant is up and running. Compared to such perplexing process, the installation of the entire Merlinmodules hardly takes any time & capital. As evident from (Figure 9) below, the Merlin modules have a special tape which is already fixed on the backside of the module. At the site, the installer/ end consumer only has to peel the tape such that the module can be stuck on to the rooftop/ industrial sheds without any hassle and/or extra material(Visit here for more info: https://youtu.be/-s7kDmb8ec8. If required, these modules can also be bolted, riveted, screwed over the rooftop. This technology enables the entire plant to be almost weightless and thus making the end consumer relaxed about the load bearing capacity of its roof.
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Figure 8: Various possible orientation of a rooftop plant (Source: Google images) |
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Figure 9: An example of peel and stick Merlin module |
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Waaree had commissioned one of its kind installations at BAPS Swaminarayan Mandir, Gujarat where 36 kWp PV power plant was installed in record 12 hours. This is by far the largest installation of flexible solar panel at a single place. We had been awarded a special order of merit for this record installation.
Figure 10: Award received by Waaree energies for installation of flexible module
Let us all pledge to make solar energy the primary source of energy in the near future.
RAHE ROSHAN HAMARA NATION
