The differences between string and central solar inverters
- Panel Talk and Technology
TrinaPro, your one-stop shop for commercial and utility-scale solar projects, combines a wide selection of products with technical support and other value-added services under the umbrella of a single provider - Trina Solar.
A central feature of TrinaPro is the option to select string and central solar inverters. Both of these types of equipment transform direct current (DC) energy into an alternating current (AC) capable of feeding into electrical grids as well as off-grid local networks. However, they have significant differences and are designed to meet separate project requirements. Let's look at how they stack up against each other, and why you might need one over the other.
Overview of string inverters and their common use cases
String inverters can be mounted on walls or the ground, and typically weigh between 120 and 160 pounds apiece, which is light for the high level of functionality they pack.
Built with mature technologies, string inverters have been in use for decades. They group individual solar panels together via connective strings – with one inverter for each set of panels – and perform DC-to-AC conversions for all of them. There are notable advantages stemming from this core design.
The advantages include modularity, low upfront costs and flexible applications. For example, multiple string inverters can be affordably installed on a project, and if one of them goes down it's straightforward to replace it with a new one. Overall, maintenance is simple because there aren't numerous moving parts. Plus, compatible accessories such as combiner boxes can further improve the utility of string inverter setups. With a combiner box, strings can be fused, reducing the overall number of strings needed for making panel-to-panel connections.
Depending on the use case, string inverters can be deployed in sizes from approximately 36 to 125 kilowatts (kW). They are also useful across a variety of rooftop, carport, ground mount and tracker installations
Examining central inverter technology and its primary applications
Central inverters are much larger than string inverters. Sizes may range from 125 kW to 2.5 MW, with even the smallest variants much larger than the biggest string inverters. Weights can reach many tons at the high end. The 2.5 MW variants can be ordered with or without transformers.
Whereas string inverters are mainstays of both commercial and residential solar projects, central inverters are exclusive to utility-scale applications. Common environments for central inverter utilization are industrial facilities, large buildings and field arrays.
The massive scale of central inverters confers several distinctive advantages, including:
- Great suitability for utility-scale ground-mounts, behind-the-fence applications and systems with consistent production across arrays.
- Cost-effective, at least when measured by capital price per DC watt compared to string inverters.
- Straightforward installation, since some projects will only need a single unit and there are fewer overall component connections than with typical string inverter layouts.
At the same time, installation is usually expensive and compounded by higher-cost combiners and DC wires. A central inverter also has a large footprint and may require more maintenance than string inverters because of the greater overall number of parts. Failure of a central inverter will be more consequential than any incident affecting a single string inverter.
Central inverters versus string inverters: Choosing the right products for your project
Inverter selection is crucial because these devices account for a major, if not the largest, portion of all hardware costs in the average solar project. There isn't a "right" selection per se, since each class of inverter has its own strengths and weaknesses that will vary in relevance between projects.
Instead, it pays to find a smart energy solutions provider like Trina Solar that can guide you through the entire process of selection, setup and maintenance. Through TrinaPro, we offer a single comprehensive platform for your solar needs. Contact us for more information on specific solution details.
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