Every solar PV install in South Africa needs surge protection. Here is what SANS expects on the AC and DC sides, and where an NRCS-approved Type 2 SPD belongs.
title: "Solar PV needs a Type 2 SPD — the SANS rules" description: "Every solar PV install in South Africa needs surge protection. Here is what SANS expects on the AC and DC sides, and where an NRCS-approved Type 2 SPD belongs." date: "2026-06-11" author: "EBB South Africa" tags: ["solar PV", "surge protection", "SANS", "Type 2 SPD"] draft: false
South Africa has added more rooftop solar in the last few years than in its entire history before it. Behind almost every new array sits an inverter worth more than the panels feeding it — plus a long DC run on the roof and an AC tie-in at the board, both excellent antennas for a lightning surge. On the Highveld, where thunderstorm days run into the seventies a year, an unprotected PV system is not a question of if it takes a transient, but when.
Yet surge protection is still the line item that gets value-engineered out of a quote. This article covers what SANS expects on a PV install, why the AC side and the DC side are two different problems, and where a Type 2 device like the PZ-C 275/40 family fits.
Why PV is a surge magnet
A grid-tied PV system gives a transient several ways in:
- The array itself. Strings of panels and their DC cabling form a large conductive loop on the most exposed part of the building. A nearby strike induces a voltage in that loop without ever touching it.
- The AC grid. The inverter's AC output is bonded to the board, which is bonded to the utility supply — the same supply that carries a switching transient every time a feeder is restored. After years of load-shedding, those restoration events are a daily occurrence on many networks.
- The earthing system. During a strike to the structure, the earth reference itself momentarily rises, and bonded equipment sees the difference as a surge.
The inverter sits in the middle of all three paths, and its semiconductors have very little tolerance for over-voltage. That is why the residual let-through voltage matters so much here.
AC side vs DC side — they are not the same problem
This is the single most misunderstood point on a PV install, so it is worth being blunt about it.
The AC side is the inverter's output and everything downstream of it: the AC isolator, the supply board, and the tie-in to the main distribution board. Electrically this is a standard low-voltage AC circuit, protected the same way as any other, with an AC surge protective device sized to the system voltage. On a South African 230 V single-phase supply that means a continuous operating voltage (Uc) of 275 V ac.
The DC side is everything between the panels and the inverter's DC input: the strings, the combiner, the DC isolator. It runs at a DC voltage that can reach several hundred volts open-circuit and needs a DC-rated SPD designed for photovoltaic strings — a different device with a different failure mode (DC arcs do not self-extinguish the way AC ones do).
The rule of thumb: an AC SPD protects the AC side, a DC PV SPD protects the DC side, and you do not substitute one for the other. A complete install considers both.
What SANS expects
Surge protection on a PV install is not an optional extra you can argue your way out of. Two standards govern it:
- SANS 10142-1, the wiring code, is the document your installation is certified against. It governs where and how SPDs are fitted on a South African board, and it pulls embedded generation (which is what a grid-tied PV system is) into its scope. If a Certificate of Compliance is issued, the SPD arrangement is part of what it covers.
- SANS 61643-11, South Africa's adoption of IEC 61643-11, defines how the SPDs themselves are type-tested and classified: the Class I / Class II / Class III (Type 1 / Type 2 / Type 3) framework you see quoted on data sheets.
The practical reading for a PV install: where a low-voltage AC supply connects to a building (and the inverter's AC output is exactly such a connection), the board should carry surge protection coordinated to the risk. For the AC supply board around a domestic or light-commercial inverter, that protection is a Type 2 device. (Type 1 combined arresters belong where a structural lightning protection system creates a direct-strike risk at the main entry — a separate decision at the building's main board, not at the inverter.)
If you want the symbols on the data sheet in plain English first, the SPD number decoder breaks down exactly what Type 2, Uc, In, Imax and Up mean before you commit to a model.
Type 2, and what the numbers mean here
A Type 2 SPD is tested with the 8/20 µs current waveform — the signature of an induced surge rather than a direct lightning strike (the 10/350 µs waveform a Type 1 device is built for). That 8/20 µs profile is exactly the class of event a PV system sees most often: nearby strikes coupling into the array, and switching transients arriving from the grid.
Three numbers then decide whether a given Type 2 device suits the job: Uc, the continuous operating voltage, which must sit above the system voltage so the SPD never conducts in normal operation (Uc 275 V ac on a 230 V single-phase board); In and Imax, the nominal and maximum discharge currents the device handles; and Up, the residual let-through voltage the inverter actually sees during a surge, the number that protects the equipment, where lower is better.
Where the PZ-C 275/40 family fits
EBB's PZ-C 275/40 is a Type 2 (Class II) per-phase surge arrester built for exactly this AC-side role. It is rated Uc 275 V ac, In 20 kA, Imax 40 kA, with a voltage protection level of Up ≤1.2 kV, in a single- pole 18 mm DIN-rail housing that drops onto any standard board. That is the right specification for a 230 V AC distribution board (including the supply board on the AC side of a domestic or light-commercial inverter) against the induced and switching surges a PV system invites.
The family covers the variations a real install needs without changing the protection circuit:
- the PZ-C 275/40 base unit for a standard board,
- the PZ-C 275/40 R with a dry-contact for remote end-of-life signalling back to a monitoring system or alarm panel, and
- the PZ-C 275/40 MODULE, a replaceable plug-in cartridge so a device that has done its job can be refreshed without rewiring the base.
One limit defines where this device goes: it is an AC-side device. It belongs on the AC distribution board, and it is not a substitute for a DC-rated PV string SPD on the DC side. A complete PV protection scheme fits both.
The compliance point that matters in South Africa
In South Africa a surge protective device may only be sold legally if it holds a valid NRCS Letter of Authority under compulsory specification VC 8055. That is a regulatory requirement, not a marketing claim. A device without an LOA has no business on a compliant board.
The PZ-C 275/40 family is approved under NRCS LOA ZAF-RCC-0029482 and type-tested to SANS / IEC 61643-11. The actual document, with its test report reference, is on the compliance page to download — not "available on request". On a PV install where the customer expects a clean Certificate of Compliance, fitting an SPD that can produce its own paperwork is the difference between a tidy QA file and an awkward conversation later.
What to do on your next PV quote
- AC supply board: a Type 2 device at the system voltage — Uc 275 V ac on a 230 V single-phase board — protects the inverter output and what's bonded to it.
- DC side: specify a DC-rated PV string SPD separately. The AC arrester does not cover it.
- Main entry: if there is a lightning protection system or high exposure, the main-board protection is a Type 1 / Type 1+2 decision in its own right.
- Verify the LOA before you buy: only fit an SPD with a current NRCS Letter of Authority under VC 8055.
Surge protection is a small fraction of the cost of a PV system and the only line item standing between a lightning season and a dead inverter. SANS treats it as part of a compliant installation — so spec it properly, on both sides.
If you are a contractor or wholesaler putting EBB protection into your PV work, our contractor and wholesaler onboarding sets up trade terms and gives you the documentation pack for your QA files.