Cost pressure is driving the development of solar energy systems that can handle 1,000+ VDC. The industry responded with standards and components enabling up to 1500 VDC. Several central inverters have been rolled out for this new market. Wall mounted, three-phase multi-string inverters that can handle more than 250 kVA are also a viable option. This is why the price gap between multi-string and central inverters is closing and the competition between these solutions is heating up for utility-scale applications.

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  • Three-phase multi-string inverters
  • Central inverters

Three-phase multi-string inverters

PV Inverter systems require DC/DC boost converters, as part of the Maximum Power Point Tracker (MPPT), to adjust the PV panel output voltage to the required DC-link voltage level. This is then input into DC/AC converter which deliver the solar energy to the public grid.

DC/DC Booster Converter

Two-level and three-level symmetric boosters are commonly used in the input stage of the inverter, and three-level flying capacitor boosters are starting to be used in the latest systems. Flying capacitor topology has best price/performance ratio compared to both the two-level and three-level symmetric topologies.

Housing Symmetric booster Flying capacitor booster
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DC/AC converter

Many different inverter topologies have been proposed in the past. NPC and ANPC are widely used in 1500 V multistring inverters. Mixed voltage NPC (MNPC) is still used in residential and commercial 1000 V systems, but is gradually being replaced by NPC. Three-level and four-level flying capacitor inverters are starting to be used in the latest systems.

Central inverters

Engineers who develop central inverters have been quick to respond to fast technological advances in string inverters. The latter are now a genuine competitor in utility-scale projects, driving the former to evolve and adapt that much faster. Two-level solutions are no longer competitive; more advanced topologies are needed to stay in the game.

Simply adapting two-level housings to three-level topologies is not the answer. This would limit the maximum frequency and negate some of the advantages of NPC and MNPC configurations. This is why Vincotech has tapped its deep well of experience with three-level modules to come up with high-power solutions. Our low inductive housings are built to handle higher switching frequencies, enabling you to reduce your overhead in passive components and achieve outstanding efficiencies.

VINco X modules meet the demanding requirements for central inverters, while retaining the string inverter's speed and flexibility. Add-ons such as integrated snubber capacitors and asymmetric inductance are available to make this an even more persuasive package. The terminal connection allows DC and AC stages to be split, which makes busbar design that much easier.

A low inductive connection for easy paralleling is also an option.

MNPC 1000 VDC modules and NPC 1500 VDC modules come with a wide variety of power ranges and semiconductors to meet each customer's specifications. The layouts are meticulously designed to guarantee even current distribution and prevent individual dies from overloading.

Housing Nominal current rating MNPC NPC
VINco X4
300 – 800 A
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VINco X8
800 – 1200 A
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VINco X12
1200 – 1800 A
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