As utilities start to build large solar projects and solar power makes up an increasingly larger portion of the electricity mix, integrating this energy into the grid will be a challenge. Solar, like wind, is intermittent — power from the sun fluctuates when clouds pass overhead and wind doesn’t blow consistently. Now General Electric, which has been a major player in helping to integrate wind into the world’s power grids, wants to do the same for solar.
The company has turned a 1.5 MW wind converter into a new, 600 kW solar inverter for utility projects, Rick Robertson, an inverter program manager at GE, told us at this week’s Solar Power International. The inverter, pictured above, is targeted at multimegawatt solar projects with multiple installations on a single site, he said. GE is now taking orders for the inverter, which was introduced at the conference, and plans to ship its first units by the end of this year, he added.
The inverter is another sign that GE sees solar as “the next wind.” It said last month that it plans to grow its solar production next year, and has also invested in technologies that could make solar cheaper.
To modify the inverter for solar, GE changed the way it connects to power projects, because solar panels generate direct current, which must be turned into the alternating current used by most appliances, whereas wind turbines generate alternating current, said Minesh Shah, a product line leader for renewables systems. GE also modified the software to enable utilities to monitor and control the solar power plants, he added. And the inverter had to be packaged with a new skin suitable for outdoor installations, as wind inverters are usually kept inside the towers, while solar inverters need to be able to survive the elements, said Tony Galbraith, an inverter program manager for GE.
When it comes to the hardware, however, GE says it hasn’t changed much, with the idea being to leverage its experience — and volume — in wind converter manufacturing. The conglomerate already makes 4,000 wind converters annually, and keeping the hardware similar will allow it to simply add new solar volumes on top of that, according to Robertson. GE also believes its reputation and track record with the wind converters will give investors confidence in its solar inverters, as it has 12,000 wind turbines in the field with 175 million operating hours at this point, Robertson said.
One of GE’s main advantages in this space is the company’s understanding of what utilities and power plant operators are looking for, so that it can make solar projects look similar to other power plant interconnections, Shah said. “We know how to turn a 30 MW system from just a collection of panels and modules into a power plant.” The software that comes with the inverter presents information about solar projects in the same way that utilities and power-plant operators are already familiar with viewing power plant data, he said, and it also enables the same level of control to manage the voltage of the electricity output so that it can be smoothly interconnected with the grid.
GE’s move into utility solar is a sign that big companies are starting to see solar as a potentially significant part of the energy mix. But in order to make that happen, the industry needs to start preparing to integrate solar into the grid now, Shah said. “In the solar industry today, people are not thinking about these types of issues,” he said. While other companies are working on smoothing the load from variable renewables, it’s true that the work at the utility level is just beginning.
Jenny Chase, head of solar research for London-based New Energy Finance, said she’s seeing a growing number of companies working on integration. With the world’s largest solar projects underway, “it’s probably quite a good thing that people are thinking about this now,” she said. You can expect to hear more about it soon. Hundreds of megawatts of utility projects are already underway in the U.S., with more announcements expected as utilities work to meet state renewable energy standards.
Graphics courtesy of GE