Tariffs
What is NMD (Notified Maximum Demand) for home solar in South Africa?
NMD / notified maximum demand is the capacity you and the utility agree your supply can draw — often visible as a breaker size or kVA limit on larger connections. Oversizing a hybrid, heat pump and EV wallbox without checking NMD is how trips, upgrade fees and nasty tariff moves appear. It is a bill and connection constraint, not a solar slogan.
Updated 27 October 2026 · Illustrative ranges — not a formal quote, credit decision or legal advice.
Answer first: Before you sign for more kW of inverter or a three-phase dream, ask what maximum demand your present connection allows and what it costs to raise. Solar that ignores NMD is unfinished design.
Where homeowners meet NMD
- Service connection / main breaker limits on single-phase suburban supplies.
- Applications that add heat pumps, induction, boreholes and 7–22 kW EV gear alongside a hybrid.
- Small business / Airbnb properties already close to the notified limit.
- Municipal forms that ask for inverter kVA and expected import demand after SSEG.
eThekwini-style network-access charges on inverter kVA are a cousin of the same idea: nameplate capacity can raise monthly floors even when you export little — demand charges · feed-in / SSEG charges.
Savings angle — upgrade only when the diary says so
A three-phase or higher-NMD upgrade has application fees, possible tariff code changes, and sometimes higher fixed charges. It pays when diversity-adjusted loads actually trip or when the metro will not clear your SSEG file on the present limit — not because a brochure shows a bigger inverter. Load-manage the EV and stagger the geyser first — single vs three-phase · EV load management.
What to put in the installer brief
- Photo of the main DB and meter / NMD paperwork if you have it.
- List of big loads with kW and whether they can shed in Stage.
- Whether the wallbox must charge during backup (usually no).
- Last 12 months kWh and tariff code.
Related: DB upgrade · max solar kW / SSEG · size a system.
Business vs home language
Commercial NMD / kVA billing is stricter and more expensive to get wrong. Shop and guesthouse owners should treat notified demand as a finance line item beside the PV quote — small business solar · Airbnb / guesthouse.
Practical discovery steps before the site visit
- Photograph the main breaker / isolator and any utility labels on the meter kiosk.
- Ask the metro or Eskom distribution desk what notified capacity applies to your stand if paperwork is unclear.
- List simultaneous loads: geyser, stove, borehole, pool, HVAC, wallbox, kiln, welder.
- Apply diversity honestly — not every load runs at once, but Stage recovery + dinner + EV is a real stack.
- Ask whether your SSEG inverter kVA itself triggers network-access or capacity charges.
Bring that pack to the installer so the first quote already respects the connection — read a quote · SSEG.
EV wallbox vs NMD — the silent breaker trip
A 7.4 kW single-phase wallbox on a modest suburban supply can coexist with a hybrid if load management throttles when the house is peaking. Without it, dinner + geyser + charge session trips the main and looks like “solar failure.” Specify dynamic load management in the charger quote — home charger cost · three-phase EV.
When upgrading NMD / phase makes savings sense
- Documented nuisance trips after diversity is already managed.
- Metro will not approve the proposed hybrid kVA on the present connection.
- Workshop or guesthouse loads are structural, not optional.
When the only reason is “the salesman said bigger is better,” stay put and improve self-use. Export credits will not repay a heavy connection upgrade on most homes — feed-in · self-use.
Small business caution
Shops billed with demand or kVA components can see solar reshape the demand pattern — sometimes helpfully, sometimes with new fixed structures after SSEG migration. Model the post-solar tariff schedule, not only energy R/kWh — small business · demand charges · commercial SSEG.
Handover note for future you
Write the notified limit, main breaker size, and any upgrade application reference into the solar file beside the CoC. The next owner (or your future EV) will need it — selling with solar · CoC.
Worked suburban stack (illustrative diversity)
Main breaker 60 A single-phase (~13.8 kVA class at 230 V). Simultaneous wish list: 3 kW geyser, 2.3 kW stove plates, 7.4 kW wallbox, 1 kW of other house load = fantasy overload. With load management that pauses the wallbox when the cooker and geyser contend, and a hybrid that covers essentials in Stage, many homes stay on the present NMD. Without management, the “solution” becomes an expensive upgrade that still needs the same discipline.
Write diversity rules into the charger and geyser timers; do not rely on memory at dinner time — EV load management · install order.
Application language that helps the utility desk
When forms ask for expected maximum demand after SSEG, answer with the managed figure and attach the load schedule. Optimistic undershooting that trips later creates compliance pain; fantasy oversizing can trigger unnecessary upgrade quotes. Honesty plus a one-line load-management description is the professional path — municipal SSEG steps · max kW SSEG.
FAQ-style edge cases
Prepaid suburban home: You may never see the letters “NMD” on a token slip, but the main breaker and any utility limitation still cap simultaneous import. Treat breaker size as your practical ceiling until the utility says otherwise.
Complex / sectional title: Common-property supplies and exclusive-use units can have different notified limits. Wallboxes on common risers need body-corporate rules plus electrical capacity — sectional title solar · apartment EV.
After solar, my import peaks fell — can I downsize NMD? Sometimes utilities allow a review; bring twelve months of post-solar demand data. Do not assume a voluntary downsize if you still plan a second wallbox next year.
Keep the conversation anchored in rand: upgrades cost money, trips waste food, and unmanaged EV charge sessions create both — monthly savings · size a system.
Link back to the savings desk
NMD is a constraint that shapes which hybrid kW and wallbox amps are even legal to quote. Get it right early and your self-use design can focus on tariff timing instead of nuisance trips. Get it wrong and you buy hardware that cannot run together at dinner time — the opposite of payback — payback · read a quote · costs & savings.
If your electrician shrugs when asked about notified capacity, pause the deposit. Connection limits are foundational; they are not paperwork trivia to “sort after install.”
When NMD bites residential projects
Adding a hybrid, heat pump, borehole and 7–22 kW wallbox can push past the notified / main-breaker limit even if each device “fits” alone. Ask the municipality or Eskom distributor what your NMD or supply size is before you accept a three-phase upgrade quote. Diversity and load management often beat a costly connection change — DB upgrade · three-phase EV · load management.
Quote language
Every commercial-leaning residential quote should state assumed supply size, whether an NMD increase is required, and who files it. Silence here is a red flag — red flags.
Quick questions
Is NMD the same as my breaker size?
Often related on small supplies, but larger connections may have a formal notified kVA distinct from a single breaker label. Ask the utility or read the connection agreement.
Does solar lower my NMD need?
Daytime PV can reduce import demand, but cloudy evenings with EV + geyser still hit the grid. Design for the worst simultaneous import, not the sunny average.
Will SSEG automatically raise NMD?
Not automatically — but your application may trigger a review. Disclose the hybrid kVA and big loads honestly.