Hardware
What AC isolator is required for home solar in South Africa?
Grid-tied and hybrid plants need correctly rated AC isolation so a registered person can work dead — typically a lockable isolator on the inverter AC output / supply path as specified by the OEM, wiring rules and the metro's SSEG pack. Exact device selection is a CoC design decision; homeowners should demand the isolator on the single-line and refuse "we'll add it later."
Updated 27 October 2026 · Illustrative ranges — not a formal quote, credit decision or legal advice.
Answer first: Ask where the AC isolator sits on the single-line diagram, whether it is lockable, and how it coordinates with the backup board and dual-supply labels. Pair with DC isolation — both matter — DC isolation · dual-supply labels · CoC · DB upgrades.
Why homeowners should care
- Emergency responders and metro inspectors look for clear isolation.
- Service techs need a lockable point before firmware or board swaps.
- Insurance questionnaires increasingly ask about isolation and labels — insurance.
AC vs DC — do not conflate
| Side | Job |
|---|---|
| DC isolator(s) | Make PV strings safe to work on |
| AC isolator | Make inverter AC path safe / inspectable |
| Backup changeover / ATS | Separate topic — changeover ATS |
Quote / inspection checklist
- Isolator shown on single-line with ratings.
- Accessible, labelled, lockable as required.
- Not buried behind storage boxes in the plant room.
- Matches OEM and SSEG drawing submitted to the metro — SSEG · inspector tips.
Common fails
Missing labels, isolator on the wrong side of a parallel connection, or a device that cannot be locked out. Fix before inspection day — inspection fails · red flags · read a quote.
Homeowner folder to keep with the CoC
Store the quote annexures, OEM manuals, serial photos, export-limit screenshots and metro reference letters together. When a future technician or buyer inherits the plant, that folder beats scattered WhatsApps — choose installer · selling with solar · warranty transfer.
Re-check fixed charges and tariff codes after any meter change so savings models stay honest — fixed charges · 2026/27 tariffs · metro tariffs hub · bill still high.
Field notes from SA handovers
At commissioning, ask the partner to demonstrate the behaviour described on this page, photograph settings, and confirm NRS-listed SKUs match the invoice. Refuse non-listed gear and export promises that ignore your metro’s live PDF — red flags · NRS list · SSEG · read a quote.
What "correctly rated" means for homeowners
You are not picking the amp rating from a Facebook group. The registered person selects an isolator that matches inverter AC current, cable size, fault levels and the OEM's installation manual, then shows it on the single-line submitted for SSEG. Your job is to refuse a quote that waves away isolation as "optional extras" — CoC · SSEG · read a quote · DB upgrades.
Lockable and accessible — why inspectors care
A device buried behind battery cabinets or above a water heater fails the practical test even if the amperage is right. Metro inspectors and future technicians need to lock out the AC path without moving furniture. Label both the isolator and the dual-supply warnings so the next person does not open the wrong board — dual-supply labels · inspector tips · inspection fails.
AC isolation is not DC isolation
DC isolators make PV strings safe; AC isolators make the inverter's grid/backup AC path workable. Skipping either side creates unsafe maintenance and weak insurance answers. Fire-safety conversations should always include both — DC isolation · MC4 · SPDs · insurance.
Changeover / ATS is a separate decision
Generator changeover switches and automatic transfer schemes solve dual-supply topology problems; they do not replace the OEM-required AC isolator on the hybrid. Keep the concepts distinct on the quote so you are not sold one device for two jobs — changeover ATS · generator interlock · diesel vs battery.
Commissioning photo pack
- Isolator nameplate and rating.
- Position relative to inverter and DB.
- Labels matching the single-line.
- Proof it can be locked out.
Store with the CoC. Buyers and insurers ask — selling with solar · warranty transfer · red flags.
Generator and hybrid coexistence
Homes that keep a diesel genset need clear interlocking so the generator and hybrid cannot back-feed each other. That interlocking is additional to the AC isolator on the hybrid path — budget both if the design keeps the genset — generator interlock · diesel fuel vs battery · changeover ATS.
DIY temptation
Buying a random isolator online and fitting it yourself is how CoCs and insurance get messy. Isolation devices belong in the registered person's design. Homeowners can demand the device on the drawing; they should not improvise the fitting — DIY risks · red flags · CoC.
Rand and paperwork discipline
Keep invoices, CoC, SSEG references, export-limit screenshots and tariff codes in one folder. When the next technician, buyer or insurer asks what was commissioned, that pack beats a WhatsApp scroll — choose installer · selling with solar · warranty transfer · read a quote.
Re-check fixed charges after any meter or tariff change so the savings model stays honest — fixed charges · 2026/27 tariffs · metro tariffs · bill still high · monthly savings.
Commissioning demo worth insisting on
Before final payment, ask the partner to demonstrate the behaviour this page describes: which breaker moves, which schedule runs, which meter SKU applies, or which isolator locks out. Photograph the proof into the handover folder with the CoC. A demo that cannot be shown usually cannot be supported later — choose installer · red flags · CoC · NRS list.
Where this page sits in the desk
Use this answer for the narrow decision, then jump to hubs for the wider plan: load shedding for Stage sizing, costs & savings for bill maths, batteries for usable kWh, panels & inverters for hardware, and check a quote before you pay a deposit. Tariff context stays on metro tariffs and 2026/27 tariffs.
Maintenance rhythm after month one
Revisit settings after the first full billing cycle and after the first serious Stage week. Export a monitoring CSV, compare to the metro bill, and note any nuisance trips or fan behaviour. Small corrections early are cheaper than annual arguments — monitoring numbers · yearly maintenance · monthly savings · bill still high.
One-page brief to send installers
Copy this page's lead paragraph into your quote request, add last-12-month kWh, tariff code, roof photos and which loads must survive Stage 4. Ask every partner to answer the quick questions at the bottom in writing. Comparable answers beat glossy brochures — get quotes · check a quote · read a quote · Stage 4 · SSEG · City Power feed-in.
Education only: confirm isolator ratings, meter SKUs, lease clauses and fan-curve firmware notes on the live OEM/metro/primary documents the week you act — ranges here are illustrative for SA homeowners comparing quotes.
Photo pack for the inspector
Photograph the AC isolator open and closed, the lock hasp, and the dual-supply labels on the same visit. Metro inspectors move faster when the pack matches the single-line — inspector tips · labels · inspection fails.
Service reality
Firmware swaps and board replacements go slower without a lockable AC point. Demand it on the quote even if the sales deck forgets — read a quote · firmware.
Quote and CoC cross-check
Before you pay the balance, match the quote SKUs to the installed serials, confirm the export setpoint screenshot, and file the CoC number with dual-supply photos — read a quote · CoC · export limit · labels · check a quote · get quotes.
Stage and tariff reminder
Hardware only pays off if it covers your real Stage windows and your metro’s fixed charges. Prefer self-use when export credits are thin — Stage strategy · fixed charges · export vs self-use · metro tariffs.
Lock the decision rule into the handover pack
Write one clear operating rule for this topic — what stays on, what stays off, which setting is correct, and who to call. Store it with the CoC and monitoring login. Households that rely on memory fail the first awkward Stage 4 evening.
Revisit the rule when you add loads or change tariff. Stale rules create expensive surprises on the next bill.
Quick questions
Is a breaker in the DB enough?
Often you still need the dedicated isolator the OEM/SSEG drawing shows — ask the registered person.
Do I need AC and DC isolators?
Yes — they protect different sides of the plant.
Can I operate the isolator myself in an emergency?
If labelled and safe to access — still call the installer for faults; do not DIY internals.
Sources & related
- Solar News 24 — DC isolation / fire safety
- Solar News 24 — dual-supply labels
- Solar News 24 — what is a CoC
- Solar News 24 — SSEG registration