Why Indian Solar Market Slowly Shifting To Half-Cut and MBB PV Modules?

India has been heavily dependent on import of solar PV modules and solar cells from China. With imposition of 40% BCD on imports of solar PV modules, the manufacturing of higher efficiency solar panels to fulfill the demands of system installers and developers. Though India has made a significant progress in solar PV manufacturing from 5.8GW in 2016 to 18GW in December 2021, but still a long way to go.

There is a high demand for high efficiency solar panels from project developers. Developers need solar modules above 400Wp for their projects to ensure high solar power generation efficiency specially to utilize a limited space in better manner. The other reason is the “cost reduction”, which is one of the key buying factors. Manufacturers have taken a step in this direction by coming up with Half-Cut Cell & MBB solar Modules. The names can be referred from the latest ALMM list.

These latest technology based high power output panel will cost similar to the traditional ones. So, what is most expected with these advanced technology based solar panels is high PV system performance and faster ROI. Therefore Half-Cut or multi-busbar technology contributes to lower energy costs along with improved system performance.

In general terms

Multi-Busbars Refers to Modules with 9-12 or 16 Busbars instead of conventional 3-5 Busbars.

Half cut Refers to modules with 120 or 144 Half-cut cells instead of regular 60 or 72 cells.

Now let’s enjoy the details

Multi-Busbar Cell Technology

Thin rectangular or cylindrical strips printed on solar cells to conduct electricity are called Busbars. The other important function they perform is that they interconnect the front of the cell to the rear side of the adjacent cell. They are generally made up of copper and silver paste. Today the most common busbar count is 5BB which was 2BB in traditional solar panels. But many manufacturers have moved a step further by using 9BB – 12BB solar cells.

A solar cell consists of thin grid fingers which are made of silver paste and are responsible to carry current from solar cells to Busbars. Solar cells upto 5BB require flat ribbons to carry the current, whereas MBB (Multi bus bar) solar cells need thin round copper ribbons to carry the current.

Benefits of using Multi Busbar (MBB) solar cells


  1. Reduced resistive losses - Multibusbars on solar cells shortens the length of grid fingers and each busbar has to carry lesser current. This reduces the internal resistance of solar cells and consequently resistive losses. As we know if the current is reduced to half the resistive losses gets reduced by a factor of four.


P loss = I2R

2. Increased optical performance – with flat tabbing wires, most of the sunlight falling on busbars, gets reflected back. But, use of rounded or cylindrical tabbing wires allows more light to reflect onto the solar cell surface thus improving the efficiency and performance of solar panel.

3. Less hot spots increased durability – Micro cracks occur due to heavy load or impact or people walking on panels. Micro-cracks (mostly parallel to the bus bars) cause the thin grid lines to break, leading to insufficient movement of electrons to busbar further resulting in partial or even entire cell failure and hot spots.

But MBB technology helps reduce the chances of cracks transforming into hot-spots by allowing alternative paths for current to flow. Smaller distance between Busbars let the cracked part of the cell stay connected with the rest of the cell through nearby busbar.

4. Cost Savings with reduced silver usage –Metallization is the process of printing silver grid fingers and copper busbars on the surface of solar cells and hence a very important part in manufacturing of solar cell. Using multi busbar reduces the usage of silver paste as the metallization process will require less amount of silver coating on the front side. The reduction of silver usage by 45%-75% ensures high cost savings.


So we discussed about how solar panels with Multibusbars promise high efficiency, more reliable and long-lasting performance . Now we will discuss about Half Cut Cell solar panels.

Half-Cut Cell Solar Panel

Majority of the panels that we see in the market today are of either 60 cells or 72 cell configuration. But with advancement in technical applications we can double the number of cells without much increase in the size of the module. This technology is the cut cell technology, where cells are cut in two equal halves and one module is split into two smaller ones and are connected in parallel.

So it is more like two small solar panels in one frame. Most of the leading solar panel manufacturers in India like Bluebird Solar, Vikram, Waaree, Adani, Tata and some others have shifted to this modern technology. But most important thing is how cutting solar cells in half and splitting solar panels in two halves is beneficial?

Benefits of Cutting Solar Cells To Half:

  1. Generate More Energy:

The full sized square solar cells are cut into two halves with laser. Diving the cell also divide the current to half thus decreasing resistance and increasing the efficiency of solar panel upto 3%. More output per square foot makes it possible to manufacture high wattage solar panels. This is the best reason to choose half cut cell panels if you want to get more power at reasonable prices. These days solar cells are also cut into 1/3 to produce high wattage solar panels above 600W

2. Low power losses

By cutting the cell into half the current gets reduced to half and the length of the bubars also gets reduced to half. This leads to reduction in resistance, Thus reducing the power losses in connecting busbars by half.

3. Less Prone To Micro-Cracks & Hot-Spots

Dividing cells make them less prone to micro-cracks. Small sized cells are more durable than full sized cells. You can see in the image that in case of full sized cell the micro crack impacted complete 1 cell. But if we divide the cell to half only a half portion gets impacted and the other half will function normally.

Multibusbars play additional role in mitigating the impact of microcracks. Thus reducing the possibility of occurrence of hotspots.


By cutting the cell into half the current gets reduced to half and the length of the bubars also gets reduced to half. This leads to reduction in resistance, Thus reducing the power losses in connecting busbars by half.

Splitting Solar Panels To Half Reduce The Impact Of High Temperature & Shadow


The sunrays we receive on earth includes a portion of infrared rays (4.5-0.7) um, visible rays (0.3-0.7) um and ultraviolet rays (0.3-0.25) um. The photons in the visible light gives energy to electrons to move from valence band to conduction band thus generating electric energy. The infrared rays are the reason behind heating of solar panel whereas UV rays can harm the cells.

The heating of solar panels due to infrared radiation impacts the performance of solar panels. The rise of temperature of solar panel above 25oC leads to voltage drop, thus reducing the efficiency and the power generated by the solar panel. Heat causes atoms and molecules to vibrate faster. So when solar cell temperature increases, the atoms starts vibrating and it makes difficult for free electrons to move without hitting these vibrating atoms. This way electron loses its energy before escaping the solar cell and doesn’t participate in electricity generation.


Effect of rise in temperature on power, voltage & current:

The temperature coefficients mentioned in the technical datasheets depicts the effect of rise in temperature on power, open circuit voltage and short circuit current when the temperature in solar panel rises 1 unit above 25oC.

The parameters above means:

  • The generated voltage decreases by 0.31% with increase in 1 degree temperature above 250C.

  • The generated current increases by 0.05% with increase in 1 degree temperature above 250C.

  • The power generated decreases by 0.31% with increase in 1 degree temperature above 250C.

  • NMOT (Nominal operating cell temperature) is the temperature of cell in open circuit when


· Irradiance on cell surface – 800 W/m

· Air (ambient) temperature – 20oC

· Wind velocity – 1m/s

The temperature of the cell may vary by +2 in summers and -2 in winters.

The temperature of solar panels can be calculated any time and at any temperature using this formula:


Tcell = TAir + (NOCT-20)/80*S

where S is an insulation level in unit (mW/cm2)

Now suppose you have a solar panel of 400W and the solar radiation is 900W/m2 , insulation level Is 90mW/cm2, ambient temperature in summer is 40oC, then

Solar panel temperature is : 40 + (46-0)/80*90 = 69oC

Increase in solar panel temperature = 69oC – 25oC = 44oC

Power generated efficiency becomes = 0.4% x 440C = 17.6%

100% - 17.6% = 82.4%

If power generated from solar panel is 400W x 82.4% = 329.6W

In actuals the decrease in power due to rise in temperature is more than the theoretical calculations.

Effect of shade on performance of solar panel:


Shade is one of the most common and harmful factors impacting the life of solar panels. When half of the solar panel gets shaded, the current generated also gets reduced to half. When one of the solar panels connected in series gets shaded then the performance of the rest of the panels in series also gets effected.


If three solar panels of same wattage are connected in series and one of them gets shaded, then the resulting current will be the lowest current in the string.


Suppose we have 3 Panels of 100W with Voltage = 17.5V & Current = 5.8A. And one panel gets shaded, that starts generating 3A due to shading. Then the current output of solar panel string would be 3A. So, shading can reduce the power output of solar panel by 50% approx..


Benefits of splitting solar panels to half


  1. Reduced impact of high cell temperature:

In months of June to August when temperature may range between 40oC – 45oC and efficiency of normal solar panels gets reduced due to rise in cell temperature. Then, use of half-cut cell solar panel can reduce the impact of rise in temperature on power output. The use of multi-busbars and split cells reduce the current passing through the busbars which further reduces the resistance. Also, due to short lengths of busbars, resistance in connecting busbars also gets reduced. This reduction in resistance in the cell leads to decrease in cell temperature and increase in efficiency of solar panel.

2. Better performance in shadow

Dividing the solar panels to two equal halves improves the shade tolerance. The solar panel split in two separate halves generates energy even if a portion of on half is shaded. In traditional solar panels when one cell is shaded the entire row within the series stop generating power.

Conventional Solar Panel

Half Cut SolarPanel

In the illustration image above where we have a conventional solar panel with 3 strings of solar cells, a solar cell in Row-1 gets shaded all the cells in Row-1 will stop functioning. This way 1/3 of the solar panel becomes non-functional.


Now in case of half-cut solar panel we have 6 strings of solar cells. The by-pass diode are connected in reverse to protect the solar panels from shading. Now assume a cell in Row-1 gets shaded then cells within Row -1 will stop functioning. Rest of the 5 strings will work normally. So, only 1/6 of the panel got affected. The presence of copper bonding tape in the middle of solar panel increases durability of solar panel.

Are Halfcut Solar Panels Future Of Solar Industry


Half-cut cells are really great for improving the solar power energy yield of panels, but they are more challenging to manufacture. This makes it hard for traditional manufacturers to switch to producing half-cell solar modules, it is not as simple as just adding half-cut cells to a production line.


In many cases, traditional solar panels can still work for you, like if your roof has ample sunlight throughout the day.

But if you need every ounce of energy you can get because you live in a shady area or you want to maximize your net metering benefits, half-cut cells make sense. Ask for half-cut cells if you have a small surface area that needs to generate all the solar power it can. Otherwise, you should be fine with traditional panels even if you might need a few more of them on your roof.


Perhaps when the manufacturing of half-cut cells becomes more streamlined and easier to adopt, they will become cheaper and more widespread.