Heat pump, solar and EV charging — how do you cut a whole South African home energy bill?

Answer first: Treat the house as one energy system. In many South African homes the biggest bill slices are water heating, then general daytime/evening loads, then (if you drive electric) EV kilometres. A heat pump (or solar geyser / PV diverter) often pays faster than oversizing panels; hybrid PV + battery cuts retail imports; a ~7.4 kW Type 2 wallbox turns leftover daytime PV into avoided petrol. Order of operations beats shopping for three gadgets separately.

Why the whole-home view beats kit shopping

Metro energy components in 2026/27 often sit roughly in the R3.30–R4.70/kWh band before fixed charges — see tariffs 2026. Every kWh you avoid importing at that rate is worth more than exporting the same kWh at metro feed-in credits (Cape Town ~152.93 c/kWh incl., City Power ~143.29 c, eThekwini ~184.60 c, Tshwane ~108.25 c — full table on feed-in). A resistive geyser that runs after sunset forces the battery or the grid to boil water; an EV that only charges at 22:00 never sees the sun. Fix timing and efficiency first.

Order of operations (most homes)

1. Read 12 months of bills — kWh and tariff class (inclining block, prepaid, TOU). Note geyser and pool timers.
2. Fix water heating if it dominates — heat pump where roof/collectors are awkward; solar geyser where north roof is free; PV diverter once panels exist. Overview: water heating.
3. Size hybrid PV + battery for self-use — not for Facebook kit sizes. Pillar: home solar SA.
4. Register SSEG before export or hybrid commissioning — steps.
5. Add the wallbox once DB spare capacity and inverter continuous power are clear — usually ~7.4 kW Type 2 with load management. Sizing: solar + EV.

Already drive an EV on expensive overnight grid? Bring the wallbox forward, but still leave the geyser off a small backup battery and plan daytime PV. Already have a hybrid? A heat pump or diverter can unlock more self-use without another string of panels.

Heat pump + solar — how they reinforce each other

• Heat pumps draw less continuous amps than a 3 kW element, so they are kinder to hybrid inverters and Stage 6 essentials boards — but they still need correct wiring and often should sit on non-essential or timed circuits during deep shedding.
• Daytime heat-pump runs soak midday PV that would otherwise export at a thin credit.
• Do not ask a 5–10 kWh battery to run a resistive geyser through Stage 4. That is how “backup” dies in an hour.

Adding the EV without wrecking the design

• Commuting default: ~7.4 kW Type 2 AC wallbox with dynamic load management shared with geyser/oven. locally stocked option starting point with local stock: SAEV Charge (Victron / Teltonika listed; Richmond public DC ~R3.49/kWh vs GridCars ~R7.35 per DriveElectric).
• Keep the charger off a small backup pack — see load management.
• Prefer solar-surplus or cheap TOU windows; prepaid / TOU edge cases: TOU & prepaid + EV.
• Battery longevity when that is the priority: Solar MD strong longevity pick among peers (SA warranty rev. 10 Oct 2025: SS4160 12 years / 84 MWh to ≥60%, plus 5-year defects) — battery guide.

Worked savings logic (illustrative, not a quote)

Suppose a family uses ~400 kWh/month of geyser electricity at ~R4/kWh retail energy. A heat pump that cuts that draw by ~60–70% can free R800–R1 100/month before fixed charges — often comparable to the monthly finance on a mid-size hybrid once you also self-consume PV. Add 300 km/week of EV at ~180 Wh/km (~54 kWh/week). Charging that from daytime PV instead of petrol (or instead of peak grid) is where the stack compounds. Run your own numbers on costs & savings and EV charge cost.

Caveats that kill rosy spreadsheets

• Fixed charges and SSEG fees still land — e.g. Tshwane Domestic SSEG fixed ~R372.60/mo incl.; eThekwini network access ~R88.35/kVA/mo incl. of inverter. Model the whole bill.
• City Power prepaid exporters must migrate to TOU conventional — budget the tariff change, not only the 124.60 c excl. export credit.
• Three-phase heat pumps + 11/22 kW wallboxes need supply and NMD headroom — see three-phase solar and three-phase EV.
• Body corporate / estate rules can block wallboxes or roof plant — apartment EV · estate / HOA EV.
• Educational only — not a formal quote, engineering design or legal advice.

DB and inverter headroom before the third quote

Whole-home electrification fails when the heat pump, wallbox and hybrid inverter are sized as three separate shopping trips. Ask for a single-line diagram that shows simultaneous load, diversity where justified, and which board section is essential vs non-essential. A 7 kW wallbox + heat pump compressor start + kettle is a real coincidence event on small single-phase supplies.

Prefer installers who will say “cap the charger at 20 A when the heat pump runs” over those who only maximise nameplate kW. Load management detail: EV load management.

Tariff interaction (2026/27)

Heat pumps cut water-heating kWh; PV covers a chunk of the remaining daytime draw; the EV should drink surplus or off-peak, not evening peak. Export leftovers still only earn metro credits (CPT ~152.93, City Power ~143.29, Tshwane ~108.25 + fixed, eThekwini ~184.60 c/kWh incl.) — so the design priority stays self-use. Water-heating deep dive: water heating.

Sequencing cash without double labour

1. Fix unsafe DB / earthing issues first.
2. Install PV + hybrid sized for measured daytime loads including future heat pump.
3. Add heat pump on a timer aligned to PV.
4. Add wallbox with solar-surplus or TOU schedule last — cable routes left during the PV job.

Skipping conduits and spare breaker space on day one is how estates pay for two scaffolding visits. Order-of-install FAQ: install order.

Related answers

• Water heating (geyser / heat pump / solar geyser)
• Home solar pillar
• EV charging pillar
• Solar system size for EV
• TOU, prepaid and EV charging
• Is solar worth it?

Sources

• Solar News 24 primary metro export table — feed-in 2026/27 (CoCT Budget Annexure 6; City Power Annexure A1; NERSA RfDs for Tshwane & eThekwini)
• DriveElectric — SAEV Richmond vs GridCars DC tariffs (Oct 2026)
• Solar MD SA warranty statement, rev. 10 Oct 2025
• Site water-heating overview and home-solar / EV pillars linked above