Scaling up string inverters in Chile


From Huawei 2021 Special Edition

ENGIE has invested heavily in Chile in recent years and some of its rooftop solar projects have featured Huawei string inverters. How would you describe the reasoning behind this choice? What is the rationale for using string instead of central inverters in Chile?

Francisco Retamal: ENGIE has plans to develop 2 GW of renewable energy capacity in Chile, and to cease its coal-fired power generation activities in the whole of Latin America by 2025. This presents an additional 1 GW since the last announcement in 2019. A big portion of this renewable energy capacity will be solar.

Alongside our transformation plan, we have developed a couple of rooftop photovoltaic systems at client sites, accompanying these clients through their own energy transition. For these projects, we have already used Huawei string inverters, learning the advantages of this technology.

String inverter technology is always the best option for rooftop projects because it has easy installation, and if one string fails, the whole array’s energy is not lost, just the power from that string. Maintenance is also simple, and you can reduce the amount of DC cabling needed. We also used Huawei string inverters in a project at Santiago’s Arturo Merino Benítez International Airport: 720 kW string inverter capacity from 14 inverters, which generate around 1.2 GWh per year of renewable energy. This project adds on to recent similar agreements with different companies for a total inverter capacity of around 1,100 kW.

ENGIE is working with central inverters for its latest utility-scale project in Chile, but the aforementioned advantages of string technology can also play out in larger projects. And given our experience in rooftop projects, we’re considering string inverter technology for utility-scale project designs.

What advantages are offered by string inverters in the Chilean PV market in terms of logistics? Are these devices the best option for all kinds of projects?

Julio Saintard: String inverters offer a high level of redundancy and plant availability; in case one of the inverters goes down, the rest of the plant continues to operate at a high-capacity level. From the installation point of view, considering that the packaging size of a string inverter is much smaller than a central one, the transport from the factory, unloading, and its disposition of the work is made easier, requiring less specialized equipment and fewer hours of labor. This optimizes execution times and reduces the risk for the project.

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What needs to be taken into account when building a solar plant with string inverters in Chile’s climatic conditions? Is the project size crucial for the choice of these devices?

JS: Most of the large photovoltaic plants are located in the desert regions of northern Chile, where the “chusca” is abundant. This is a kind of dust with very small granulometry, that requires components rated with at least IP65 protection, as well as a comprehensive maintenance plan to be carried out according to the specific site conditions. Site selection is also relevant in terms of corrosivity – many areas of northern Chile reach the ‘C5 – very high’ classification, based on the ISO standards. Finally, the size and flexibility that a site has for mounting systems also have implications in terms of required earthworks and the need for seismic certifications.

Chile is known for having the highest levels of solar radiation in the world. Would ENGIE only use string inverters in a similar environment?

Christopher Llanos: It is one of the options that we are considering. Project feasibility for any technology will depend mainly on the LCOE of the overall project, taking into account the advantages on opex, capex, and yield of the complete project can have.

How are O&M and monitoring activities being implemented after project completion? And how would you describe the ongoing after-sales service from Huawei?

FR: We have received solid customer service from Huawei, based on strong knowledge of string inverters and clear communication for solving problems and supporting ENGIE with different post-sales requirements. In addition, we have had a very positive experience with Huawei’s monitoring platform, which gives us the opportunity to watch our PV systems operating in real-time.

Looking forward, is the share of string inverters expected to Increase in ENGIE’s projects in Chile?

FR: It is possible, but it will depend on the market and on how the economic variables of the project between one solution to another move, and their impacts on the overall cost of the project.

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