Sungrow Commercial String Inverter Guide: SG33CX to SG110CX

For commercial rooftop and ground-mount projects in the 30 kW to 500 kW range, selecting the right string inverter model affects commissioning time, long-term maintenance cost, and annual yield. Sungrow's SG-CX series covers this segment with five models — the SG33CX, SG50CX, SG60CX, SG75CX, and SG110CX — sharing the same transformerless, IP65 architecture while scaling MPPT count and power output to match different project sizes and rooftop geometries.

Why Choose a String Inverter for Commercial Solar?

Central inverters dominated large C&I projects through the 2010s, but the string inverter has become the default for commercial rooftop and medium-scale ground-mount work below 500 kWp. The reason is fundamental: distributed architecture eliminates any single point of failure. If one inverter in a string array develops a fault, only that section goes offline — the rest of the plant keeps generating. With a single central inverter, any fault takes the entire array offline until a service team arrives.

String inverters also reduce commissioning complexity. Each unit connects directly to its dedicated string array, with no DC combiner boxes or medium-voltage step-up transformers in the equipment chain below 1 MW. Maintenance engineers can swap a faulty unit without specialist transformer or high-voltage equipment certification. For C&I rooftop projects where site access is constrained and downtime directly reduces a building's self-consumption savings, these practical advantages outweigh the small efficiency difference between string and central topologies. String inverters now dominate C&I rooftop installations from 10 kW through 500 kW globally, and Sungrow's SG-CX series is among the most widely deployed platforms in this class.

The Sungrow C&I String Inverter Range

The SG-CX series consists of five three-phase, transformerless string inverters designed for commercial and light utility applications. All models share a common IP65 enclosure rated for direct outdoor installation without an additional ventilated cabinet, an integrated DC disconnect switch, a built-in AC circuit breaker, and 24/7 remote monitoring via the iSolarCloud platform. The range runs from the SG33CX at 33 kW — well suited to smaller commercial rooftops between 50 and 80 kWp — to the SG110CX at 110 kW with 12 independent MPPT inputs, designed for complex multi-orientation rooftops above 150 kWp or straightforward commercial rooftops requiring fewer inverter installation points. All five models support the AFCI arc-fault protection option and zero-export (zero-injection) mode for self-consumption projects.

Specifications at a Glance

The table below summarises the key electrical and mechanical specifications across the SG-CX range. All five models share a common 1100 V maximum DC input voltage and 98.7% peak efficiency, enabling a consistent string design approach across a project portfolio.

All models: IP65, -25°C to +60°C operating range, built-in AC/DC switch, AFCI option available.

MPPT Configuration and String Design

The number of independent MPPT (maximum power point tracking) inputs is the most important specification for rooftops with multiple orientations, inter-row shading, or shadow from rooftop equipment and parapets. Each MPPT tracker independently optimises the strings connected to it, so modules on a south-facing slope and modules on an east-facing slope can each operate at their individual maximum power point without one section dragging the other down.

The SG33CX offers 4 MPPTs and is ideal for simpler rooftop geometries with one or two orientations. The SG50CX, SG60CX, and SG75CX each provide 6 MPPTs, making them well suited to rooftops with up to three distinct sections. The SG110CX's 12 MPPT inputs allow a project designer to allocate independent trackers to each rooftop section, parapet-adjacent row, and equipment shadow zone without combining mismatched strings onto a shared tracker. This flexibility can recover 2–5% of annual yield compared to a lower MPPT-count inverter on the same complex rooftop — a meaningful difference across a 20-year asset life.

For DC/AC loading ratio, Sungrow recommends a range of 1.1 to 1.3 for the SG-CX series on typical commercial sites. At higher clipping ratios, the annual clipping loss begins to outweigh the capital saving from fewer string inverters. Your Econo Solar engineer can model the optimal ratio for your specific location's irradiance profile and module selection.

Grid Code Compliance and Built-in Features

All SG-CX models ship with anti-islanding protection and a full suite of reactive power control modes. Operators can set a fixed power factor, use Q(U) volt-var mode as required by Australian AS/NZS 4777.2, European VDE-AR-N 4105, and similar grid codes, or configure zero-injection (export-limiting) mode for self-consumption projects where grid connection agreements prohibit net export. All modes are configured via the iSolarCloud commissioning interface — no additional hardware relay or external controller is required.

The optional built-in AFCI (arc-fault circuit interrupter) uses high-frequency impedance measurement to detect DC arc faults in string wiring before they can ignite rooftop insulation or structural materials. US NEC 690.11 requires AFCI on all roof-mounted systems, and increasing numbers of commercial fire risk assessors in Europe and Australia specify it as a design requirement regardless of local code. Econo Solar supplies SG-CX units with the AFCI option fitted at the factory on request. Each unit also includes a built-in DC string monitoring function that measures individual string currents, flagging deviations consistent with soiling, shading, or cell degradation without additional monitoring hardware.

Monitoring with iSolarCloud

All SG-CX inverters include lifetime access to Sungrow's iSolarCloud platform at no additional cost. The platform provides string-level current and voltage monitoring, real-time fault alerts via push notification, daily and monthly yield reporting, and over-the-air firmware updates — eliminating site visits for software maintenance. For commercial asset managers running multi-site portfolios, the platform's multi-site dashboard aggregates generation data across all connected plants, enabling a single operations team to monitor system health from a single screen.

iSolarCloud supports third-party SCADA integration via Modbus TCP and SunSpec-compliant protocols, making it compatible with most commercial building energy management systems. Data export is available in CSV format. Remote fault diagnosis tools allow Econo Solar's technical support team to review inverter logs and recommend corrective action without an on-site visit — a significant advantage for projects in remote or access-constrained locations.

How to Order from Econo Solar

Econo Solar stocks the full SG-CX range as an authorised Sungrow distributor and can provide FOB pricing within 24 hours of a written RFQ. All orders include factory datasheets, installation manuals, and grid code compliance documentation for the target market. Commissioning guides and iSolarCloud activation codes are provided with each shipment, and our technical team is available for pre-commissioning support via video call.

For orders above 1 MWp, dedicated project management is available to coordinate delivery phasing, documentation packs, and warranty registration directly with Sungrow. To request a quote, send your project capacity, module selection, target delivery port, and preferred Incoterms to [email protected] or use the quote form below.