Solar Power Distribution for Industrial Facilities: A South African Guide

The financial case for industrial solar in South Africa crossed a threshold it won't come back from. With Eskom's Megaflex tariff delivering blended costs between R1.60 and R2.20 per kWh—and solar PV generation levelised at R0.80–R1.10 per kWh over a 25-year system life—the arithmetic is unambiguous. Plant managers and CFOs across manufacturing, agri-processing, mining, and logistics are making the investment.

But "solar makes financial sense" is only the first question. Once a facility commits to solar PV, a cascade of electrical engineering decisions follows—decisions that determine whether the system is safe, grid-compliant, and actually delivers the returns it was designed to achieve. Most of those decisions live not in the panels or inverters, but in the distribution infrastructure that connects them to the plant.

Why Now: The Regulatory Shift

For years, the most significant barrier to large-scale industrial solar wasn't financial—it was regulatory. South African facilities above 1 MW had to obtain a generation licence from NERSA, a process that routinely took 18 to 24 months and introduced enough uncertainty to stall most projects at the feasibility stage.

The 2021 amendment to Schedule 2 of the Electricity Regulation Act changed this. The self-generation threshold was raised from 1 MW to 100 MW, meaning the vast majority of industrial solar projects now require only compliance with the relevant grid codes—not a NERSA licence. Projects that would have been stuck in licensing limbo for two years can now be designed, procured, and commissioned in six to twelve months.

This regulatory shift, combined with tariff increases averaging 11% per annum over the past decade and the structural memory of load-shedding embedded in industrial risk calculations, is why the pipeline of industrial solar projects in South Africa has accelerated so sharply. It is no longer a niche technology for ESG-focused multinationals—it is mainstream capital expenditure.

The Distribution Infrastructure: Where the Engineering Decisions Live

An industrial solar PV system is not simply an array of panels and an inverter. It is a distributed generation asset that must be safely and reliably integrated into an existing electrical distribution system—one that was almost certainly designed for unidirectional power flow from the utility. Getting the distribution side right is what separates a project that performs as modelled from one that requires expensive retrofits or fails grid compliance testing.

Point of Connection

The inverter output connects to the facility's existing distribution at the point of connection (POC)—typically the main LV distribution board (LVMDB) for systems up to approximately 500 kW, or at the MV level via a dedicated transformer for larger installations. The choice of POC determines the fault level the switchgear must handle, the protection functions required, and whether existing switchgear is rated for the combined fault contribution of the utility and the inverters.

This is a critical design input that is frequently underestimated. Main switchboard busbars sized for utility-only fault current may be undersized when solar inverter fault contribution is added. A fault level study should be performed before finalising the POC and before any switchboard upgrade scope is costed.

Bidirectional Power Flow

Legacy industrial distribution systems were designed to move power in one direction: from the utility incomer to the loads. Adding solar PV introduces bidirectional flow—solar generation moves toward the loads and potentially toward the utility incomer, while utility supply flows in the conventional direction.

Switchgear, including automatic transfer switches (ATSs) and bus couplers, must be verified or upgraded to handle this correctly. An ATS configured for a standby generator application—where the transfer logic assumes a single source of generation—may not correctly manage the combination of grid supply, solar generation, and battery discharge. ATS programming must explicitly account for solar generation to prevent solar output from being exported onto an isolated section of the utility network during a fault or maintenance outage.

Protection Requirements

NRS 097, the South African grid code for embedded generation, mandates specific protection functions at the grid interface. These are non-negotiable for utility connection approval:

• Anti-islanding protection: Prevents the solar system from energising a section of the utility network while Eskom maintenance personnel may be working on it. Most modern inverters implement anti-islanding via frequency and voltage detection, but the function must be verified against the specific network characteristics during commissioning.
• Overvoltage / undervoltage and over/under-frequency protection: Disconnects generation when grid conditions fall outside acceptable limits.
• Earth fault detection: Required to detect loss of earth continuity at the distribution interface.

Many of these functions are implemented within the inverter, but larger installations often require external protection relays to provide independent, type-tested protection at the grid connection panel—particularly where the utility specifies relay-based protection as a connection condition.

Metering

Revenue metering for embedded generation is separately mandated under NRS 097. A dedicated generation meter—revenue class accuracy—must be installed with appropriately sized current transformers (CTs). The metering must capture import, export, and generation values for utility billing reconciliation and, where applicable, for municipal wheeling arrangements. Cape Town's wheeling framework is the most mature in South Africa; several other municipalities are developing frameworks that will allow industrial generators to sell excess energy to third parties across the distribution network.

What Plant Engineers Need to Specify

For engineers putting together a solar integration specification, the distribution side of the project requires the following to be explicitly addressed:

Inverter type and interface voltage. Three-phase string inverters are standard for rooftop systems up to approximately 500 kW; central inverters for larger arrays. For facilities with MV distribution infrastructure or systems above 1 MVA, MV-output inverters or dedicated step-up transformers avoid the need to run LV cables over long distances to each inverter string.

Switchgear fault ratings. Specify the prospective short-circuit current (PSCC) at the POC after adding inverter fault contribution. SANS 61439 requires that all switchboard components—busbars, MCCBs, contactors—are rated to the prospective fault level at that point. Do not reuse existing switchboard fault ratings without verification.

Protection relay scheme. Define whether inverter-internal protection functions are sufficient or whether a dedicated external relay is required at the grid connection panel. This decision should be made in consultation with the utility or municipality supplying the connection point—requirements vary between Eskom and municipal distributors.

Metering and data acquisition. Beyond revenue metering, industrial solar systems benefit from energy management system (EMS) integration—real-time visibility of generation, consumption, export, and battery state of charge. Specify metering with appropriate communication protocols (Modbus RTU/TCP, IEC 61850, or DNP3) for integration with plant SCADA or energy management platforms.

Earthing coordination. Transformerless inverters are cost-effective and increasingly common, but they have specific earthing requirements. TN-C-S (PME) earthing systems—standard in South African industrial facilities—are incompatible with certain transformerless inverter topologies without additional isolation transformers. Resolve this in the design stage, not during commissioning.

Common Pitfalls

Undersized main busbar. The most frequent and expensive retrofit. Size the main busbar for combined utility and inverter fault contribution from the outset.

Incorrect ATS programming. Anti-islanding is not only an inverter function—the ATS transfer logic must also prevent solar export to the utility network during an outage. Programme and test this explicitly during commissioning.

Missing power quality verification. Harmonic injection from large inverter installations must be measured and confirmed compliant with NRS 048-2 before handover. Noncompliance can result in utility disconnection notices.

No distribution O&M plan. Panels and inverters absorb most O&M attention, but switchgear, protection relays, and metering equipment have their own inspection and testing requirements. Include these in the commissioning documentation and O&M schedule from day one.

GNTech's Role in Solar Integration Projects

GNTech supplies the distribution and switchgear infrastructure that connects solar generation safely into industrial facilities—the infrastructure that enables the panels and inverters to actually do their job within a compliant, reliable electrical system.

This includes purpose-built solar AC distribution panels incorporating inverter terminations, revenue metering, CT installations, generation isolation switching, and NRS 097 protection relay interfaces in a single compliant assembly. For facilities requiring upgrades to their main distribution, GNTech supplies bidirectional-rated main distribution boards designed for solar generation duty, with protection coordination accounting for inverter fault contribution. For larger installations, MV integration switchgear handles medium-voltage connection without the LV infrastructure overhead.

Telergon and Pronutec components—both stocked by GNTech—are proven in South African solar integration applications, with local support and spare parts availability that matters when O&M performance over a 25-year system life is part of the financial model.

GNTech's application engineers work with solar EPC contractors from the design stage to ensure distribution infrastructure is correctly specified—avoiding the costly retrofits that arise when panels and inverters are connected to switchgear that was never designed for embedded generation.

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Planning a solar PV project at your facility? Contact our team to arrange a site survey and engineering consultation—we'll assess your existing distribution infrastructure and specify what's needed for a safe, grid-compliant solar integration.