Consensus in the solar industry is that it is gradually shifting towards monocrystalline cell technology from the more common multicrystalline (also called multicrystalline) cells and modules. The introduction of passivated emitter rear contact (PERC) cell technology has markedly increased the efficiency of monocrystalline cells, making them an economically attractive option for many projects. However, the use of multicrystalline modules still dominate the market in India, though developers have begun to seriously consider mono perc modules as they come with several important advantages.

How has the technology evolved?

Both multicrystalline and monocrystalline modules are made from silicon. When producing a multicrystalline cell many fragments of silicon are melted together to form a wafer. Due to the presence of many crystals in each cell, there tends to be less space for electrons to move within the cell, resulting in an overall lower efficiency of the cells.

During the monocrystalline cell production process, silicon is transformed into bars and cut into wafers. A single-crystal silicon is used in this process which gives the electrons greater room and more freedom to move, resulting in a higher efficiency compared to multicrystalline cells.

For a non-PERC module to become PERC, two modifications need to be carried out: First, a passivation film needs to be applied to the rear end of the module (called the rear passivation stack) and secondly, this rear passivation stack needs to be opened and tiny pockets need to be created in the applied film in order to increase the light absorption. Mono PERC is also more efficient than multi because mono has more space for electrons where as in multi, there are many crystals in a single cell occupying extra space that electrons could have used.

Additionally, changing the non-PERC production lines to PERC doesn’t require significant investment in the production lines.

The market

Solar markets around the world are markedly shifting to mono PERC, and India is expected to follow suit. Based on our market survey, mono is expected to be the dominant module technology globally with over 50 percent of the market share forecasted in 2018.

“High efficiency mono PERC modules could have a significant impact on the Indian solar market not only for their expected higher ROI, but also in the reduced use of land when these modules are used in large-scale projects. Land availability has been a challenge in India and technology that minimizes land use while maximizing energy output will be a difference maker” says Raj Prabhu, CEO of Mercom Capital Group.

Many large-developers in the country are already evaluating the viability of mono PERC and have determined that these modules will become mainstream sooner rather than later.  Mercom spoke with manufacturers operating in India to get their thoughts on the transition to Mono PERC modules.

Manufacturers

Ivan Saha, BU-Head Module Manufacturing & CTO, Vikram Solar responded when asked to choose between the two panel types. “Both monocrystalline and multicrystalline solar panels serve the same function in the overall solar PV system: they capture energy from the sun and turn it into electricity, both have their own pros and cons,” Saha contends.

He continued, “Multi has been the mainstream product for many years and has a long-proven history. So still a large part of India’s module mix is dominated by multicrystalline . As far as mono is concerned, recent trend has shown a substantial increase in market share. Mono being high efficiency modules have many more advantages over its counterpart. From having better space utilization to longest solar panel life, and from better efficiency to having superior heat tolerance, it has numerous wins over multicrystalline. With advanced process technology like PERC, efficiency has risen up to ~22% at the cell level. The best in-class efficiency of multicrystalline-based solar panels to monocrystalline solar panels varies between ~1 to 1.5 percent for 72 cells modules.”

Daniel Liu, Strategy Director and Asia South Managing Director, Jinko Solar, said, “Comparing the two technologies, mono is definitely a superior technology. Due to the lower silicon purity, multicrystalline solar panels are not quite as efficient as monocrystalline solar panels. They also lead to lower space-efficiency. You generally need to cover a larger surface to output the same electrical power as you would with a solar panel made of monocrystalline silicon.”

Dr. Rahul Kapil, Operation VP and Director, Longi Solar, said, “LONGi has a strong conviction for mono. We believe that mono will have major market share. The reason for the market dominance by these modules will be their higher efficiency and their potential to increase their efficiency level even further to touch the module efficiency limits. Another reason in support of mono modules is the higher energy yield from these modules. Higher energy yield from mono comes from the low temperature coefficient of mono modules, low operating temperature in the field, better performance at low irradiation and lower LID (Light Induced Degradation) and slower power degradation in the long term. Due to the above reasons mono modules’ energy yield is higher than multi and as a result, it reduces the levelized cost of energy (LCOE).”

Dr. Kapil also stated that the efficiency of normal mono and PERC cells are typically 20.3 percent and 22.2 percent respectively, while a multi cell has typical efficiency of 18.9 percent.

Waaree Energies commented, “When comparing monocrystalline solar panels and multicrystalline solar panels, mono is considered a better option, as it is technically more enhanced than the latter. These are the most premium solar panels available today, and as a result, are slightly costlier than the rest. Also, monocrystalline solar panels perform best in warm weather conditions. However, these solar panels possess the most efficient rates in the market, besides being especially compact, and thereby taking up very little space.”

According to Waaree, “The approximate difference in efficiency between mono and multi-crystalline modules would be between 1 and 2 percent. Mono-crystalline modules are made from the highest grade of silicon and have the highest efficiency among modules.”

The trend

In discussing the current trend in the Indian and international markets, Saha opined, “As India and the world are rapidly accepting solar as the best replacement for fossil fuels, solar technology is quickly improving to satisfy the growing demand. The world is now interested in monocrystalline solar panels and we see the mono PERC becoming the mainstream product in next 1-2 year. With recent market trend showing a rapid decline in multicrystalline module market share, demands for new module technologies i.e. bifacial and half cut modules have risen manifold. At present, large-scale developers are persisting with multi crystalline silicon, however, with rooftop and residential market, we see change in demand shifting to monocrystalline modules; this increase is mainly due to its superior space utilization and aesthetic. Further, we are observing a shift from 1,000 to 1,500 system voltage in the past years.”

Adding to the same topic, Liu stated, “During the early solar years, we saw multi-crystalline flooding the market but we are now seeing an industry trend shift from multi to monocrystalline modules. This transition can be attributed to several factors including high efficiency and cost advantage. Now with PERC technology in place, this shift is even more prominent, owing to greater margin control for manufacturers. Also, PERC being a mature technology, it will be mass produced and be seen gaining market share rapidly. In India, if we trace the trend for the last couple of years, we will see that in 2017, the poly and mono ratio stood at 95 percent and 5 percent respectively. In 2018, it is at 85 percent poly and 15 percent mono. So, it can be deduced that developers are going to opt for mono as it leaves about 8-10 percent impact on the BoS (balance of systems) cost of the developer.”

Elaborating further on the market trends, Dr. Kapil said, “We are seeing the trend of market shifting toward mono. If you see the trend, before our entry downstream, mono market share in China was less than 5 percent; the other technology, multi, accounted for the other 95 percent. In 2015, our first full year in modules, the China mono market grew to 15 percent, then 27 percent in 2016 and 36 percent in 2017. In the first half this year, according to third party data, mono market share in China is now over 50 percent. We are also seeing an increased acceptability of mono modules in Indian market which was previously dominated by multi modules. We believe that in the India, the market trend will be toward mono due to its high energy yield, reliability, field performance and lower LCOE. From the technology perspective, we see that PERC will be a standard product and in 2019, bifacial will be widely available for the customers. From our experience, the developers are accepting and showing interest to move toward mono as this adds value to their project.”

According to Waaree, “The current trends depict a rising number of customers shifting from multi to mono-crystalline solar panels, based on the technologies that are coming up. In fact, in the United States, mono-crystalline modules are used in majority of the solar projects installed in the country. Over the last few years, the demand for mono has grown significantly, with close to 50 – 60 percent of the solar modules in use in the world being mono-crystalline ones. While multi-crystalline solar panels were widely in use earlier, the last few years have seen the industry witnessing a rapid and widespread shift to mono-crystalline solar panels, with more and more projects being developed using them.”

Production shift

Saha stated, “Yes, at Vikram Solar we produce both mono and multi crystalline silicon modules and in different wattage ratings depending on customer requirements. You must be aware that moving from multi crystalline to mono crystalline in module production is not a significant change and we have both our module technologies as certified products. Our annual capacity stands at 1 GW for module manufacturing. Depending on the market demand and order pipelines, the required capacity can be allocated between mono and multi module manufacturing without any constraint.”

Liu replied, “Yes, Jinko produces both multi and mono-crystalline modules. Depending on the customer needs, we can offer both the technologies. We have a diverse product range ready to meet the market requirements and the annual capacity for mono including PERC and standard is 12 GW while we stand at 5 GW capacity for multi.”

Dr. Kapil told Mercom that LONGi has converted all its lines to mono PERC and at present is its standard product offering. Kapil stresses that LONGi is a mono technology company and only produces mono ingot, wafer, cells and modules with 28 GW wafer and 12 GW of module manufacturing planned by the end of 2018.

Waaree stated, “Waaree Energies can produce both mono and multi-crystalline modules. Based on the preference of the customer, we can mold our capacity to deliver what is required. Waaree Energies has 1.5 GW manufacturing capacity. We can deliver both mono and multi-crystalline modules depending on the requirements.”

Liu also added that the Indian market is huge with a great potential for solar. He sees real growth in terms of installation numbers wherein the country has achieved ~26 GW until now, and that that this growth comes on the back of policy support from the local government, serious market players, as well as healthy renewable energy funding. Liu highlights that a common trait through the years has been low pricing, so it is important to understand that to ensure sustainability of the entire solar chain, the tariffs should be checked. Otherwise, the industry as a whole may struggle going forward. Developers should now look at quality, reliability and durability of modules while installing projects. Liu warns: Do not compromise on the quality, BoM and efficiency to meet the tariffs.

When asked, module manufacturers as well as developers reiterated that the cost of mono PERC is around $0.24/W to $0.27/W. The average selling price (ASP) of mono PERC is typically 10-15 percent higher compared to multicrystalline modules.

It is clear that across the globe, major solar panel manufacturers are making the shift to mono PERC modules, and the Indian solar market wants to follow suit. As the demand for these higher efficiency mono PERC modules grow, the number of manufacturers making these panels is likely to increase exponentially.