EQ conducted a webinar on ‘Central VS String Inverters in Big Utility Scale Power Plants’, powered by KEHUA TECH, on May 31, 2021 at IST 04:00 PM. The speakers of the webinar expressed their views on central and string inverters. Dr Y. B. Reddy, AGM (PV), SECI and Dr Shailendra Kr. Tiwari, AGM (RE-Engg), NTPC were the keynote speakers. Mudit Jain, Head- Research, Tata Cleantech Capital Limited, participated as Moderator.
Sudhir Pathak, Head (Solar, wind Design and QA), Hero Future Energies, Manoj Kumar Goyal, Deputy General Manager, Design & Engineering, Azure Power, Bimal Jindal, Director, SCM, SB Energy, C Chaudhary, Chief Operating Officer, Amp Energy India, Atul Gupta, AVP, Solar IPP, Jakson Group, Shashank Dubey-Manager Sales, EnKing International, Deepak Kumar Thakur, Partner, L&L Partners, Saurabh Aggarwal, Business Development Head & Channel Sales Head, KEHUA TECH and Saravanan.M, General Manager, Design & Engineering, Ayana Renewable were the other speakers in the webinar.
Dr Y. B. Reddy, AGM (PV), SECI, said the topic is relevant. “Both central and string inverters are good, but the applications and locations always determine the requirement of the kind of inverter. Central is so far leading the market. In recent years, the string inverter is also slowly coming up.”
With the emergence of the new tracker, technologies and bifacial technologies, the string inverters will have added advantages. In terms of redundancy, the central inverters cannot provide services, especially to the projects in remote locations. So when a service is in need at a specific time, it is not possible.
We can always have one or two spares depending on the capacity in the case of string inverters. We can change them when needed. The redundancy can improve, and the downtime will be less. The emergence of energy storage is also opening up a new avenue for string inverters. So, I think the future is with string inverters.
Maybe, it may go to micro-inverters also once the efficiency improves. I think domestic manufacturing can set up easily in string inverters. It can come up in the country easily compared to the central inverters that require a large set-up for testing facilities. Also, local manufacturing needs promotion.”
Mudit Jain, Head- Research, Tata Cleantech Capital Limited, said, “Thank You, Dr Reddy, it was quite obvious that you are strongly supporting string inverters and shift away from the central to string.”
Dr Shailendra Kr. Tiwari, AGM (RE-Engg), NTPC, shared his views. “The solar PV industry is the fastest-growing power industry. Nowadays, it has become the cheapest source of energy. Other sources of energy are fighting to compete against this.
Inverter constitutes hardly three to four per cent of the project cost, but it handles the most diversified functions like power conversion, grid support, power quality etc. The inverter is a peculiar item. It can make the efficiency as good as 99 per cent and can also make theoretical zeroes.
Both central and string inverters have their pros and cons. They are in the market and aggressively competing with each other. The product should be comparable in terms of performance by cost to stay in the market.”
Bimal Jindal, Director, SCM, SB Energy, who has a unique advantage of handling one of the top five largest portfolios discussed the key reasons for the selection of central or string inverters. “So far, we have executed on central inverters in all of our projects. I believe the trend in the inverter market is changing now.” He shared his views on the topic.
Further, he spoke on string inverters, “There is an advantage in terms of execution. The construction part is much better in terms of management and execution. We will see how that goes. We are focused on central. The shift is happening on the string, but it is still not there.”
Saravanan.M, General Manager, Design & Engineering, Ayana Renewable, expressed his views specifically on central and string inverters. “Basically, string inverter can yield better from my point of view.
We are also trying to use string inverters as such but the results coming out of LCOE analysis is not so conducive or in favour of string inverter so far.” He also spoke on the total cost of ownership. “Probably when you consider the total cost of ownership for 25 years, string inverters may make some sense. As of now, based on the inputs, we are still not hitting the mark.
Atul Gupta, AVP, Solar IPP, Jakson Group shared his views on the topic and discussed the cost advantages and disadvantages of string and central inverters as per the present situation. “We are one of the developers who have used both the inverters. There is an advantage of string inverters. On excel, there is a real improvement by 1.5-2 per cent at least on excel. We are still waiting for the actual results. We want to see data of at least a couple of years.
We are amongst the developers who want to keep projects long term. So we as developers try to use what is best on the market as of now. String inverters are costly as compared to the central. Keeping in mind the long term benefits of what a string inverter can bring in, it makes sense if you want to keep the asset long term.
String Inverter is a long way to go. Keeping in mind the benefits and the way the costing is coming down in case of string inverters, I think there will be a time when the market will be totally on string inverters rather than the central inverter.”
Manoj Kumar Goyal, Deputy General Manager, Design & Engineering, Azure Power, discussed other challenges that string inverter may face when it comes to a compliance issue. “In my opinion, the inverter is an electric model of turbine generator set because it has to take care of every change happening in the grid. Therefore the compliance is taken care of by the inverter if we are talking about a larger-size utility project.
The selection of the string or central inverter is very vital. I would say central’s performance in terms of response in terms of grid compliance is a bit faster as compared to the string inverter.” Manoj Goyal discussed the inverters based on compliance issues.
Sudhir Pathak, Head (Solar, wind Design and QA), Hero Future Energies expressed his views. He said it is a debatable topic. In his opinion, the importance of string inverters is increasing because of six reasons.
These aspects are- the size of the plant is huge, the block size is increasing, the land shape is changing, most of the land is in Rajasthan, modules are ever-changing, and as a way forward, all the modules will be naturally bifacial.
“Once we take all these aspects into account, the string inverter is my best friend because it is solving all the problems. At the compliance part, I agree there is a debate about who responds faster-central or string.” He further discussed the two inverters in detail. “I am completely a buyer of a string inverter,” he added.
Deepak Kumar Thakur, Partner, L&L Partners said, “The success of any solar project is highly dependent on the availability of contiguous land and which has east obstructions. However, it has become a matter of concern in the present time that there is hardly any contagious lands.
That is why in my experience, at least in the last 1-1.5 year, I am observing most large-scale projects, for example, more than 30MW projects, are all being implemented on separate pieces of land. There are issues of inverters connectivity and transformers. Availability is increasingly becoming more and more difficult.”
Saurabh Aggarwal, Business Development Head & Channel Sales Head, KEHUA TECH said, “Both Central and string inverters have their own advantages and disadvantages. The central inverter is not an easy technology to manufacture. Right now, we are in the phase of transition where we feel both central and string inverter is getting transmitted.” He discussed both inverters in detail.
C Chaudhary, Chief Operating Officer, Amp Energy India explained his views on central and string inverters. He discussed the advantages and disadvantages of both the inverters in detail. “Both central and string inverter will grow, but string inverter will grow much faster than the central. This is the forecasting 2-3 years down the line. There is future and prospect for the string inverters,” he said.
Shashank Dubey-Manager Sales, EnKing International shared a presentation on carbon credits and carbon markets. “Currently, we are the top carbon credit developer and supplier of the world. We are the first company in the world to get listed in the stock market, BSE.”
He shared details on carbon credit and the professional process of working on a carbon credit project. Also, he shared details on the types of projects executed by EKIESL, carbon standards, future of compliance and voluntary markets.
Saurabh Aggarwal shared a presentation on Intelligent Power Management, informing about KEHUA, its capabilities and what all products the company offers to support customer demands. “The company is a 33-year old power conversion expert in the field of energy and critical power.” He shared details on the business layout of the company, its market shares and milestones. The webinar concluded with an interactive Q and A session.
