On this episode of Solar Spotlight, Benjamin Heitmann, marketing manager, and Madeline Acri, applications engineer with Sungrow North America discuss the company’s history of manufacturing solar inverter technologies and dive into some of the specific features of string inverters.
A written portion of this podcast is below but be sure to listen to the full episode on your preferred podcast service.
SPW: What is Sungrow’s company mission?
Benjamin Heitmann, marketing manager, Sungrow
Benjamin Heitmann: Sungrow’s mission is simple yet powerful, and that’s to provide clean power for all. Sungrow USA Corp. is a leading provider of renewable energy solutions, specializing in the development and manufacturing of photovoltaic inverters and energy storage systems as a subsidiary of Sungrow Power Supply Co., a global leader in the renewable energy industry. Sungrow USA is dedicated to driving the growth of clean power in the United States. We offer a comprehensive range of products and services designed to optimize the performance and efficiency of solar power installations.
Can you provide some background on solar inverters and specifically string sizing?
Madeline Acri: An inverter is a device that converts direct current electricity to alternating current, and Sungrow makes solar inverters, which convert DC power from solar modules to AC power that feeds the utility grid. The energy in PV inverters only flows one direction from DC to AC. Sungrow also has the energy storage division, which manufactures power conversion systems, also known as PCS, which is a bi-directional converter. PCS can convert DC from a battery, or solar source, to AC from the grid, and it can also take the AC grid power as an input to charge the battery.
When we talk about string sizing, we’re going to consider module selection, array orientation, and the quantity of modules inputted into a solar PV inverter.
Can different types of modules be installed on a single inverter?
Madeline Acri, applications engineer, Sungrow
MA: Well, the short answer is it depends. For each inverter, there are different design parameters for the DC PV inputs. The PV side is what you would be evaluating to determine how many different modules you may be able to use. There are physical connection points on the inverter where the positive and negative wiring runs will plug into the inverter. Some inverters have only a single DC input, but other inverters could, for example, have up to 24 DC inputs. Depending on the style of the inverter, you may have more or less flexibility on module type based on the PV input connections and MPPTs.
What happens if a PV string voltage exceeds 1000 V?
MA: The 1000 VDC design limitation is really dependent on the inverter type. But for our rooftop inverters, let’s specifically say the SG36CX-US, and the SG60CX-US, 1000 V is our maximum DC voltage operating range. If we exceed this value, the inverter will experience a fault. It will say PV input mode error, and the inverter knows to shut down and disconnect. Then it will try to reconnect again once it senses that this input voltage has lowered and is within the operating range.
So, that’s something to consider if you’re working on a rooftop in North America. Typically, the limitation is 1000 VDC, if you’re in a commercial setting, and with a ground mount, that level is 1500 VDC. You want to consider your site when you consider how many modules to connect in series, because that string length is measured based on those different codes. The inverter is smart enough to know that if the PV string voltage does exceed the operating threshold, the inverter will shut down.
This podcast is sponsored by Sungrow
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