Digitisation driving solar conversion
The solar industry is becoming more digitised, thanks to the increasing sophistication of string inverters capitalising on the benefits of a more distributed solar architecture to improve reliability and service availability. The trend toward digitisation also brings cost savings, with the replacement of traditional electronic components with cheaper silicon chip-sets. Smart modernisation could enable the technology to be not only a power generation component, but also a smart PV controller that incorporates power conversion, remote control, data collection, online analysis and environment adaptation.

The solar revolution will be digitized.

In fact, it’s already happening. The digitization of the solar industry is becoming a reality as string inverters get more sophisticated.

James (Yuyu) Qiao, vice president of operations & product solutions for Huawei Smart PV Solution North America, a Chinese manufacturer of string inverters, likes to compare the evolution of inverters to computing.

“We used to have the mainframe computing system, a very big computing system shared by many people that was a centralized architecture,” he says. “Eventually, the central architecture of the data world evolved to become more of a distributed architecture of the sort used by Google and Facebook, with greatly improved reliability and service availability.”

This is an important development for solar developers interested in reliability and increased control over the performance of their investments, says Qiao.

For one thing, a distributed architecture that utilizes many string inverters instead of a few central inverters means that any technical problems are not an immediate emergency. Nor is the move from a centralized to a distributed architecture in solar a huge lift management-wise.

“In the telecom world, providers can handle hundreds of millions of smartphones,” he says. “Why not tens of thousands inverters that don’t have roaming service?”

A commitment to string inverters

As a company, Huawei is so convinced that the future of solar will be built around string inverters that it discontinued its central inverter business in 2014. The company, which has its roots in the telecommunications industry, has also significantly ramped up its investments in string inverter R&D and innovation.

In 2015, Huawei devoted $9.2 billion of its $60.8 billion in revenue to R&D. Over the last decade, Huawei has invested over $37 billion in R&D and has six R&D centers around the world devoted to developing and improving string inverters. In total, Huawei has over 800 engineers working to improve inverter design and functionality and reduce costs.

Qiao says the philosophy driving Huawei’s inverter innovations is tied directly to what the company’s customers say they need to be successful. “We are focused on the customer and their experience from end to end. We optimize our product design based on things we understand from the field,” he says. “It’s not just some technical experts creating technical ideas.”

What solar developers tell Qiao and his colleagues at Huawei they need are three things: higher yield, lower cost and improved reliability. Consequently, providing those essentials to solar power-plant developers through string inverters is also the only goal of Huawei’s engineers.

“We are not spread out resource-wise,” he says. “We have more R&D and technical resources than other players in the market, and we focus those resources strategically on string inverters and thinking only about how to improve their customer value and strengths.”

The brains of the solar plant

Not surprisingly, given Huawei’s history in telecommunications, much of the company’s innovation efforts are focused on delivering the benefits of information communications technology to string inverters.

“We believe in a fully digital world,” says Qiao. “The inverter should be able to monitor what’s happening in the field and understand the problems of the panels, the trackers, the energy generation, and environmental changes and report issues of performance back to the operation center, and people can manage everything remotely. That is the convenience brought into the picture by digitalization.”

In 2015, Huawei introduced its FusionSolar Smart PV Management System, which leverages digitization and data analytics to allow for accurate remote monitoring of a solar plant’s performance at the individual string level. This means that whenever a string of panels is not generating as much energy as it should -- perhaps because of module degradation or shading -- the solar plant operator can quickly identify the issue and schedule maintenance to fix the problem and return yield to where it should be.

The move toward digitization also brings significant cost savings. For example, traditional central inverters have used power electronics systems with large copper busbars and other copper components. By contrast, Huawei replaces expensive copper with lower-cost silicon chipsets -- made even more economical because they’re made by Huawei subsidiary HiSilicon -- whenever possible.

“We believe with advanced digitalization we can use more chipsets in every stage of power conversion while improving, optimizing and monitoring performance,” says Qiao. “Instead of working on physics to make busbars thicker or breakers larger, digitalization gives us the efficiency and manageability of silicon without the expense of copper.”

Eliminating parts and grid manageability

String inverters also reduce O&M expenses. For example, Huawei introduced its Smart PV string inverter, eliminating parts susceptible to failure and replacement, like fuses, fans, and even LCD screens, which degrade quickly in the outdoor environment. That was possible because of improved design and the lower capacity of each unit, which means the inverters produce less heat than central inverters.

Indeed, there’s a big difference between a 30-kilowatt string inverter and a 1-megawatt inverter when it comes to heat. “If the efficiency of both is 99 percent, then the wasted energy of the 1-megawatt inverter will be 10 kilowatts,” says Qiao. “That 10 kilowatts will be turned into heat and you have to get rid of the heat and keep the equipment cooled down and operating. Because the string inverter has a lower capacity there will be less wasted energy for each unit, and we can use natural cooling instead of fans or even air-conditioning. It improves the reliability, lowers the cost, and prolongs the life of the system.”

There are other cost advantages with string inverters, says Qiao. Their relatively small size and weight means they can be installed and maintained without the use of a crane. It’s also much easier to manufacture string inverters in bulk on an automated production line because the components are standardized.

“For a central inverter, if you want to build one, you have intensive labor involved. For a string inverter, it’s a small standard unit and can be made through an automated production line,” says Qiao. “That means less labor, and we can support mass production of the same unit. That is one of the reasons why we can get the costs lowered down so dramatically. Today, when a central inverter is ordered, it typically takes months to get it built and delivered from the factory. Tomorrow, when string inverters are needed, you may be able to buy them off the shelf in a store like Costco or Lowe’s.”

Grid benefits and the future

Improved performance and manageability of solar plants also provides benefits to grid operators, argues Qiao. When a large solar power plant relies on a relatively small number of central inverters, the failure of just one can have an immediate impact on the quantity and quality of energy supplied to the grid. With string inverters, a single failure is of little consequence to either the overall plant or the grid. “The ups and downs of solar plants will always create problems for the grid,” he says.

Digitization and advanced communications also provide better responsiveness and visibility to grid operators. “Utility companies have stringent requirements -- if anything is about to go wrong, they want to be warned in advance and be able to take actions. If anything actually does go wrong, they want to see it and know that the system will automatically take action in milliseconds to fix it,” says Qiao. “When there is a power factor change and you expect the inverter to adjust itself, our technology can do that. We can help grid owners smooth out bad things happening in remote places.”

The benefits of string inverters will only accelerate as costs continue to move downward and innovation increases.

“The majority of innovation in the coming years will be to improve system availability and environmental adaptability and to optimize end-to-end lifetime cost and management automation. Digitalization, artificial intelligence, large-scale software and management will all play a more and more important role in the solar industry,” he says.

Accurate data generation about how a solar plant operates will also continue to improve, Qiao says. “The ability to collect, analyze, visualize and utilize more accurate data will be the innovation trend for the future. It all relies on the string inverters. They can improve the efficiency of the end-to-end process for solar developers, from asset management and tracking the construction and maintenance of the solar plant, to collecting data to maximize energy yield and performance.”