Technology in the solar industry is rapidly advancing, with larger solar modules with a power rating of 600W+ becoming the new standard.

The shift has prompted upgrades in project designs to accommodate these larger modules, which generate more power and necessitate enhancements in all other associated equipment.

The demand for high-capacity string inverters, ranging from 250 kW to 350 kW, has surged to meet these design requirements.

The recent Mercom India webinar, “Cutting Edge PV Inverters: Optimizing Generation from Advanced Technology Modules,” highlighted the pivotal role that PV inverters play in maximizing energy generation from advanced technology modules in the Indian solar market.

The panelists comprised Goutam Samanta, Head of PV Technology at Juniper Green Energy; Sunil Panigrahi, Country Manager- India at Hopewind; Anuj Mathur, Regional Manager, North Region at Hopewind, and Shiv Mishra, Head of Operational Excellence and Commissioning at Sterling & Wilson, Ex CGM(RE) NTPC.

Priya Sanjay, Managing Director, Mercom India, moderated the session.

Insights on Inverter Selection

High-capacity inverters are critical in cost reduction across Balance of System (BoS) components, labor, and overall project expenses. The operational costs are also expected to decrease because fewer inverters require maintenance.

Samanta said, “When we developers select an inverter, our typical criteria involve evaluating the levelized cost of electricity (LCOE), assessing the CAPEX and OPEX costs, with the inverter’s performance being the primary factor. In this context, both the module and the inverter hold immense significance, as the inverter truly serves as the heart of solar systems.”

Samanta elaborated, “First, we must consider the AC block size, followed by DC overloading. In the past, the AC-DC ratio was 1:1, but now it has increased to 40-50%. Another critical factor is the inverter’s efficiency. The module efficiency currently ranges from 21-22%, and with mono PERC cells, it reaches around 23%. In this regard, inverter efficiency is equally crucial and should exceed 98.8%.

Additionally, uptime is essential, aiming for around 99%, ensuring the system functions as intended. Lastly, an operating guarantee is vital. For instance, in a 100 MW project, the inverter must consistently perform and possess effective mechanisms for peak hours or when the system faces stress due to overloading.”

Emphasizing the importance of choosing the right inverter, Mishra felt it was important to ensure the selected product was tailored to the specific project site.

He said, “Often, I have observed owners attempting to cut corners in this regard. The selection of inverters, modules, and site locations are all interconnected factors that must be carefully considered to ensure their compatibility with each other. These criteria collectively contribute to the project’s value. Working within grid compliance presents a substantial challenge in today’s landscape. It’s a comprehensive package and not a one-size-fits-all solution.”

Addressing the unique challenges of solar projects in India and the utilization of inverters, Panigrahi explained, “India’s vast expanse encompasses diverse geographical terrains. We continually invest in research and development (R&D) to cater to these varying landscapes. We’ve conducted extensive R&D to create equipment tailored to specific environmental conditions. We are well-prepared, with products designed to suit a range of environments, whether it’s the arid Thar desert in Rajasthan or the plains of Tamil Nadu.”

The Grid Security Factor

Samanta, emphasizing the importance of choosing the right inverters from a design perspective, noted, “Accuracy is paramount, considering factors such as climatic conditions and voltage losses. Firstly, the clipping mechanisms must be flawless, and secondly, reactive power compensation should be an integral feature of inverters. While there are numerous considerations, we must ensure a foolproof system.”

Mishra expanded on the role of inverters in providing grid security and the consequences of inadequate selection, “This is a pressing issue that affects both owners and EPC companies. Selecting the right inverter and technology based on a project’s flexibility can be challenging. Recent instances of inverter failures underscore the importance of conducting proper project assessments.”

“In reality, the inverter serves as the heart of the project. From a grid compliance standpoint, it’s everything. Making the wrong selection or lacking flexibility in the chosen inverter can lead to setbacks. I recommend thorough studies encompassing all parameters, instilling confidence in the product for developers and EPC companies. Ultimately, this benefits everyone involved,” he added.

String Inverters: Maximizing ROI

While discussing the improved compatibility of string inverters with new technology modules, Mathur commented, “String inverters, with their higher capacity, such as 250 kW, can play a pivotal role in enhancing the ROI (return on investment) of solar projects. They reduce equipment costs and BOS components, lower installation expenses, elevate system efficiency, and enhance monitoring and control capabilities. This is especially critical in utility-scale projects, simplifying grid integration. Choosing an inverter that fulfills these requirements facilitates seamless grid connection.”

He also noted that opting for fewer inverters with higher capacities has the potential to save space in the inverter room, decrease the physical footprint of the solar installation, and potentially reduce infrastructure costs.

Smart Inverters: A Technological Evolution

Mathur, discussing the significance of smart inverters, emphasized, “Smart inverters represent a significant technological leap and are pivotal in the ongoing evolution of the grid. They extend beyond the fundamental task of converting direct current from solar panels into alternating current suitable for the grid. These inverters have the unique ability to both consume and produce power, contributing to grid voltage stabilization. Additionally, they can automatically adjust their power output in response to voltage variations.”

Panigrahi forecasted, “In the next five years, TOPCon technology will likely gain prominence, followed by the emergence of HJT technologies. Despite a slight 2-3% efficiency difference, we are well-prepared. Our inverters are already compatible with these cutting-edge modules. We are continuously evolving and keeping pace with the rapid evolution of module technology. We recognize that HJT adoption in India entails significant CAPEX but is an inevitable progression.”

He added, “HJT technology is on the horizon. Major players are already working on cost-reduction strategies, and we eagerly anticipate its arrival. We are fully prepared to embrace these latest technologies, committed to delivering the best inverters through extensive research and incorporating feedback from our users.”

Panelists stressed the pivotal role of inverters in solar projects, from cost reduction to grid stability and their adaptability to evolving technologies, with the overarching theme being the importance of careful selection and continuous R&D to meet the changing demands of the solar industry.

You can watch the webinar here.