From Energy Storage to Microgrids, String Inverters Are the Key to Expanding Solar’s Capabilities

When it comes to the future of the solar power industry, some trends have built up enough momentum to be pretty close to inevitable — the continuing importance of operational cost reductions, the escalating need for storage and the ongoing development of microgrids, to name just a few. 

These and other important trends in the solar industry are on the radar of the China-based string inverter manufacturer, Huawei. 

The quest to push costs down

Already, it’s possible to see the vital role string inverters are having on solar’s continuing growth — particularly when it comes to driving down costs so that solar can compete with and replace fossil fuel generation.

“The future trend of the solar plant will be higher level of reliability and lower operational costs,” said James (Yuyu) Qiao, vice president of operations & product solutions for Huawei Smart PV Solutions North America.

String inverters help with both.

Lower operating costs are directly related to improved reliability, which Qiao notes is a function of both string inverter higher reliability design and the evolution toward a distributed solar plant architecture.

Having a multitude of string inverters instead of a few central inverters means solar plant operators are not as susceptible to failure-related downtime. Indeed, if a string inverter at a solar plant stops working, it has only a small impact on generation because only a very limited number of panels are affected.

And with advanced communication and artificial intelligence technologies embedded inside each of the string inverters, the network of inverters in a solar plant can form an autonomous system, which makes it possible to compensate the energy loss by team effort.

The robustness of solar plant operation has been greatly improved thanks to the wide adoption of string inverters in solar system design. String inverters can also be replaced quickly at little expense in case of failure and maintained at close to zero cost because, unlike with central inverters, they don’t need to be replaced with a crane and typically don’t require frequent onsite repair or trouble shooting which need to be performed by highly skilled engineers.

But Qiao believes we’re still at the early stage of the cost reduction journey. Additional improvements will come as string inverters get more intelligent and allow for higher level of automation. “The more intelligent string inverters are, the higher possibility we can have automated end-to-end processes and most economical power supply,” said Qiao. “That ultimately leads to lowest level of operational costs and highest revenue stream.” 

For that to happen, string inverters need to have the right hardware and communications capabilities to enable a solar power network, remote monitoring and automatic troubleshooting when generation slackens at a solar power plant. This is already possible with Huawei’s FusionSolar Smart PV Management System, which was introduced in 2015. This allows solar plant operators to continuously monitor performance without actually being out in the field. 

Another important step to reduce costs is standardization. “It’s just like the laptop computer, pads and smart phones. They are all standardized,” said Qiao.

The cost efficiencies possible with string inverters are significant, and include the components used to make them.

“Solar system components, even the components inside the inverter, can be standard so that component suppliers can manufacture in mass volumes and drive down the costs,” he said. “I think standardization and modularization can keep driving the string inverter industry to lower costs and make the solar solution more competitive compared to other energy sectors.”

How long will it take? Huawei, which has its roots in both telecommunications and power electronics industries, is convinced that it will be fast.

In part, Qiao believes a rapid transformation is possible because the technology, at least in Huawei’s string inverters, already exists. “Both the hardware and standard management interfaces are ready for this level of standardization. Our inverters already have embedded power electronics technology, communication technology and automation intelligence inside the inverters,” he said.

What remains is for standards organizations to devise requirements the entire industry can embrace. How long will it take?

“The telecom industry went through the process and it took tens of years,” he said. “But the solar industry can leverage that experience and make it much faster, possibly less than 5 years to reach a mature stage.” 

Costs go down, storage and microgrids go up

For solar power plants to become a more significant component of the electricity mix, storage will be required to improve dispatchability. “There are a lot of issues that can be solved by energy storage,” said Qiao. “Energy storage will definitely be the future and Huawei is supportive of that.”

Though Huawei doesn’t manufacture batteries for energy storage, Qiao says there’s an important connection between string inverters and storage.

“Put simply, intelligent string inverters working in tandem with batteries can help schedule, monitor, and optimize its battery charging and discharging — which is important when it comes to minimizing the energy cost, maximizing the value of stored energy, and extending the life of batteries,” he said. “Advanced string inverters can provide more precise control of charging and discharging, keep monitoring the health of battery cells, and prolong their lifespan.”

Interest in microgrids paired with solar installations is also increasing, particularly as a way to increase the resilience of a community’s energy supply when hurricanes and other natural disasters hit. One benefit of microgrids is the potential for groups of businesses and citizens to buy and sell solar electricity from one another.

String inverters can help make this possible for a couple of reasons. 

For one, string inverters are flexible enough to be appropriate for a wide variety of solar systems.

“For the microgrid, string inverters will play an even more important role because of its flexibility in terms of the capacity need of the solar system and in terms of the ways to install,” said Qiao. “Whether it’s rooftop, or wall-mounted, or ground-mounted, string inverters always provide flexibility and higher yield and more accurate data to manage PV panels and storage.”

The data management capabilities of string inverters could become increasingly important if more and more people and businesses buy and sell electricity from one another. As Qiao sees it, the string inverter can facilitate these business transactions.

“The possibility exists that some time in the future, you may be able to sell and buy electricity directly to and from your neighborhood,” he said. “The smart string system with distributed computing power may interact with the cloud, automatically collect local and remote energy availability information, analyze the tariff in real-time, make smart transaction decisions for your benefit with or without your intervention. I think this level of intelligence we can foresee happening in the next 5 to 10 years, though that’s probably too conservative.”

As solar evolves and becomes a more dynamic part of the energy mix, string inverters will become the digital backbone of the digital grid. 

from GTM Solar https://www.greentechmedia.com/articles/read/string-inverters-are-the-key-to-expanding-solar-capabilities

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