Few solar companies understand the importance of fast and efficient project commissioning as well as First Solar.
With a total of 17 gigawatts of projects installed across the globe, First Solar has experienced both easy and bumpy commissioning processes. Through all of that first-hand experience, First Solar has identified a handful of ways in which the speed of commissioning has the potential to impact the all-important economics of a project.
When done right, faster commissioning can translate into labor cost savings, particularly in states like California where union workers wages are relatively expensive. Rapid commissioning can also mean that revenue from the generation of electricity begin sooner rather than later.
“Faster commissioning may allow for the owner to receive more revenue from ‘test energy’ on the project,” said Troy Lauterbach, vice president of First Solar Energy Services. “Faster commissioning may allow the plant to reach COD [commercial operations date] earlier, therefore receiving revenue from the project earlier than expected.”
The good news: Project commissioning has been getting more efficient, just as modules, inverters, and actual construction times have improved over the past few years as well.
“We have seen the rate of commissioning improve as technology and methodology have evolved over the last decade,” said Lauterbach. “The rate of improvement in the speed of commissioning has a similar correlation to the rate of building the entire project.”
This matters in the solar industry more than ever. With competition fierce, margins thin and prices continuing to drop, the need to squeeze unnecessary costs out of every aspect of building a solar power plant has become increasingly important.
“The commissioning process is part of the capex investment for the whole PV plant, and it’s a significant enough part of the initial capex that easing commissioning through labor and material savings can really contribute to the overall capex savings of the system,” said Jiyong Lian, director of services for Huawei’s North America Smart PV Plant Solution.
Huawei, the world’s largest manufacturer of string inverters, is focused on making commissioning faster and more efficient in the future. Already, Huawei has used the power of string inverter design to speed commissioning, particularly in comparison to larger central inverters.
Even though EPCs have long been comfortable with large central inverters, their size and weight has often slowed down commissioning, in part due to their size, which requires installation on a concrete slab using heavy and expensive equipment. Commissioning with central inverters also requires that a technician from the inverter manufacturer be present — a requirement that can slow down and add expense to commissioning because of travel, scheduling and the added cost of paying the technician.
By contrast, large solar power plants using Huawei string inverters can be deployed using a block design approach that divides projects into 3- or 4-megawatt sections. Not only are string inverters light enough to be lifted into place without equipment, their commissioning is accelerated by the use of a cluster rack and an integrated transformer with both the AC and combiner box that reduces wiring and components. Commissioning for string inverters can go faster because they have fewer safety concerns.
“When you deal with the DC combiner boxes for central inverter solutions, the unit combiner box has potential shock hazards with arc flashes,” said Lian. “With us, during the installation the compartment remains closed because we have DC connecters built in under the inverter cabinet. When you connect the DC strings to the cabinet, there’s no shock hazard.”
The actual evolution of string inverter technology can also improve commissioning speed and efficiency.
“We can get a lot of power out of the same form factor. For instance, we launched the 100 KTL inverter with the same form factor as our 45 KTL,” Lian said. “It’s more than double the power density, which is more savings on capex because you can deal with a lot less AC combining effort.”
Although First Solar has limited experience commissioning string inverters, Lauterbach said the company’s initial experiences have been good. One aspect that is particularly appealing is the fact that there is no need to troubleshoot if one of the inverters isn’t working.
“You simply rip and replace with another inverter and continue the commissioning process,” he said. “At the end of the commissioning process, you just ship the non-functional inverters back to the OEM for troubleshooting.”
In the future, Lauterbach hopes to see faster commissioning through an increased use of plug-and-play equipment components. “Grid emulation is a key component to improvement in the future,” he said. “The more that components can leave the factory having been preconfigured, the faster the commissioning work in the field moves.”