As new technologies are yet to be proven, the industry needs to make optimum use of technologies that are currently dominant
By Richa Chakravarty
Friday, April 18,2014: The solar industry in India is getting more competitive and the race is on to increase the efficiencies of solar panels. For long, the industry has witnessed the competition between crystalline silicon and thin film technologies, but besides these two technologies, some new and promising solar PV cell technologies have also entered the market. However, as these new technologies are as yet unproven, the industry needs to make optimum use of the current ruling technologies.
Here’s a look at some of the new technologies that are gaining ground. Though these are yet to catch on, the survival and success of the solar market in India depends on newer technologies and their adoption by users.
Concentrator cells: This is a multi-junction solar cell technology that integrates semiconductor and optic engineering to increase cell/module efficiencies. The main limitation of this technology is the need to track sunlight with high precision. A small error in accuracy levels could lead to the solar panels that use these cells being unable to generate any power.
Inkjet printed cells: The semiconductor is in an ink form, which can be printed using a screen printer, thereby reducing the use of semiconductors and driving costs down.
Non-silicon based cell materials. The use of non-silicon-based cell materials in solar modules eliminates the complex semiconductor manufacturing process and drives costs down.
How to choose solar panels
With users aiming for better performance from their PV projects, manufacturers are on their toes to make their solar panels more efficient and reliable.
Efficiency and reliability are the most important factors to look for in solar panels. The existing technologies offer greater potential to increase efficiency and reliability. Currently, the module level efficiency of crystalline silicon is at 15 per cent and thin film is at 9 per cent. “In the last one year, crystalline PV has shown a remarkable rise in efficiency and is close to reaching 21 per cent at the cell level. R&D done during the late 90s, such as with passivated emitter rear contact (PERC), passivated emitter rear locally diffused (PERL), passivated emitter cell series (PESC), etc, has come in handy today to harvest more power at the crystalline cell level. At the string level, maximum power point tracking (MPPT) of optic engineering (to increase the light trap mechanism) is taking place simultaneously to reduce power loss and increase power generation,” informs Raghunandan, vice president, engineering, Kotak Urja Pvt Ltd.
Kotak Urja uses PV modules with laser fired PERC cells to offer high efficiencies. These modules come without any negative power tolerances and comply with IEC 62804 standards for potential induced degradation (PID) resistance. Explains Raghunandan, “The developers and users have to understand that the performance of the module is a function of its operating temperature and, hence, rated efficiency is quoted at a standard temperature of 25°C. The overall efficiency of the PV module reduces with the increase in module temperature. Hence, the user must differentiate between the PV module rating at standard test conditions and actual usage conditions. Our PV modules use innovative components, which keep modules at relatively lower temperatures than usual. This will enable power plants to harvest more power than normal.”
PID resistant panels: There are two types of degradation that happen on solar cells—potential induced degradation (PID) and lighting induced degradation. The choice of raw material has an impact on the PID. Most test samples reveal that the module samples laminated with poly vinyl butyral (PVB) show high susceptibility to PID, and most thin film modules made using PVB have the possibility of high PID. Hence, developers should look into this aspect as well when applying the technology. “While this is an important deciding factor as to which technology to opt for, developers should also check what’s appropriate for a particular location, based on radiation data. Using the right solar modules for a particular area is another major factor to be looked at. The same technology may not be optimal in all parts of the country,” advises Sunil Goel, vice president, Maharishi Solar Technology Pvt Ltd.
Raw materials used: The reliability factor directly influences the efficiency of the module. If the components used do not ensure reliability, the module’s power output drops steeply even though the cells used are capable of generating their best. Further, the components used must resist the stress caused by the environment or else they tend to result in the sudden and sharp degradation of the module.
Most industry experts are of the opinion that the sharp drop in yield during Phase I of the Jawaharlal Nehru National Solar Mission (JNNSM) could be due to the PID, since Phase I contained more of imported modules and there was no proof of PID resistant modules being used. The project developer needs to look at details of the components used before negotiating a price. There are several instances of cheaper modules being opted for and the power performance dropping steeply, noticeable only after a year or two. “It is recommended that developers check that the module supplier has a strong knowledge of the product, rather than getting swayed by mere presentations. It is also important that the supplier has a strong domestic market presence even if it is an MNC brand. The module supplier should also have proof of manufacturing modules for a reasonable period of time so that there is proven experience in module production and defects are eliminated. And the module maker must have proof of the power generation capabilities of the supplied modules,” warns Raghunandan.
Custom-built modules: Most of the manufacturers today are building modules that are designed to increase curb appeal, improve aesthetics and increase adoption in residential or commercial solar installations. Waaree Energies has introduced its colour series of PV modules that come with coloured cells and vibrant designs, while its flexible series of PV modules can be used on any curved or hard-wearing surfaces. According to company claims, its modules, which combine aesthetics and performance, are of the highest quality, are cost-effective and top rated in output power.
Efficiency alone is not the criteria to select a module. The key to selecting the right module is a combination of parameters—efficiency, reliability, logistics, mounting structure design, inverter sizing, ease of maintenance, etc. As there is an established PV module manufacturing base in India, the drive to use domestically made modules and cells will help the industry to grow at a faster pace.
Electronics Bazaar, South Asia’s No.1 Electronics B2B magazine
