Backup & loads
Can I run my whole house on solar and battery in South Africa?
Yes for some homes — if the inverter continuous and surge ratings, usable battery kWh, and essentials-vs-non-essentials design honestly cover stove, geyser, pumps and evening Stage — but most suburban quotes intentionally leave non-essentials off backup to keep cost sane. “Whole house” on a brochure often means a transfer switch path that still trips when the kettle and oven coincide.
Updated 27 October 2026 · Illustrative ranges — not a formal quote, credit decision or legal advice.
Answer first: Decide whether “whole house” means (a) every circuit can island, or (b) every priority circuit survives Stage while big thermals stay grid-tied or scheduled. Write that definition on the brief before you compare rand figures.
What whole-house actually costs in design
- Inverter continuous kW ≥ diversified running load; surge ≥ motors and some electronics.
- Usable battery kWh ≥ hours of autonomy you refuse to fail, above SoC reserve — usable kWh · SoC.
- DB split or intelligent load control so one oven start cannot collapse the island — stove/oven · geyser · induction.
Honest tiers
| Tier | Typical scope | Who it fits |
|---|---|---|
| Essentials island | Lights, Wi-Fi, fridge, routers, TV/office when required | Most suburban hybrids |
| Extended backup | Above + selected plugs, garage door, small AC or heat-pump assist | WFH / medical / security-heavy homes |
| Whole-home island | Nearly all circuits, large battery, careful diversity | High budgets; often three-phase |
Related sizing: Stage 4 · Stage 6 · size a system · heat-pump + EV whole-home.
Loads that break “whole house” dreams
Resistive geysers, underfloor heat, large aircons, borehole pumps and EV wallboxes are the usual villains. Soft-starts, timers, heat-pumps and daytime EV charging fix more quotes than buying a second inverter on impulse — aircon · borehole · EV from solar.
Grid still matters
Even whole-home islands usually keep a municipal account for winter weeks, SSEG compliance and cheaper energy when the sun is weak. Off-grid is a different brief — hybrid vs off-grid · SSEG.
Document pack to keep with this answer
Store serials, SoC/export screenshots, SSEG references and the metro meter appointment beside your CoC. Future installers and buyers argue less when the folder is complete — read a quote · selling with solar · warranty transfer.
Diversified load table (fill with your watts)
| Circuit group | Running W (yours) | On backup? | Notes |
|---|---|---|---|
| Lights + IT + fridge | — | Usually yes | Baseline essentials |
| Geyser / heat-pump | — | Only if sized | Timers; heat-pump often kinder — heat-pump vs geyser |
| Stove / oven / induction | — | Rare on small hybrids | stove · induction |
| Laundry / dishwasher | — | Daytime self-use | laundry self-use |
| Borehole / pool | — | Careful | borehole · pool |
| EV wallbox | — | Usually grid or solar daytime | EV from solar |
Sum the “yes” column for continuous kW and for kWh across your longest Stage slot. That is the honest whole-house (or extended) brief — essentials · Stage 4.
Single-phase vs three-phase
Whole-home islands on large electric cooking and AC often push three-phase hybrids and balanced boards. A single-phase 5 kW unit with a 6 kW oven is a maths problem, not a brand problem — single vs three-phase · inverter size · NMD.
Phased path if cash is tight
- Essentials hybrid + modest usable kWh.
- Add panels / battery when monitoring proves daytime headroom — expand later.
- Move selected thermals to heat-pump or daytime timers before buying a second inverter.
Related: whole-home heat-pump + EV · read a quote · size a system.
Field notes for can i run whole house on solar battery sa
Bring this page to the commissioning visit. Ask the partner to demonstrate the behaviour described here, photograph the settings, and store them with the CoC and SSEG reference. When a future technician inherits your plant, that folder beats a WhatsApp voice note — choose installer · read a quote · selling with solar.
Also keep metro tariff PDFs and OEM warranty sheets dated. News headlines and brochure stickers age; annexures decide disputes. Cross-check fixed charges after SSEG so savings models stay honest — fixed charges · 2026/27 tariffs · metro tariffs hub.
Worked suburban example
A Pretoria home wants lights, IT, two fridges, garage door, fibre, and a heat-pump geyser assist through a 3-hour evening Stage 4, while oven and 7 kW wallbox stay off-backup. Essentials average ~1.1 kW → ~3.3 kWh for the slot, plus 25–35% SoC reserve and inverter losses. That points at a mid-size usable pack and a hybrid continuous rating comfortably above 1.1 kW with surge headroom for the garage door — not a brochure “whole house 5 kW” sticker that also lists the oven.
Move the oven or underfloor onto backup and the continuous kW jumps; keep them off-backup and cook before 20:00 instead. That behaviour change is cheaper than another battery rack — stove/oven · heat-pump · Stage 4 · SoC.
- Write coincidence: kettle + microwave + aircon start is the real inverter test.
- Measure actual essentials with a plug meter or clamp over one Stage week.
- Revisit after adding EV miles or a borehole — borehole · EV + battery sizing.
- Confirm NMD / main breaker headroom if you also grid-charge hard before slots — NMD.
Commercial guesthouses and Airbnbs should price guest-facing circuits separately from owner essentials — dark guest rooms cost reviews — Airbnb / guesthouse · holiday home.
Quote language that separates marketing from maths
Ask every partner to strike “whole house” unless the single-line shows every circuit on the backup output and the continuous/surge table covers your coincidence loads. Prefer quotes that say “essentials board as annexed” with a circuit list. That wording survives Stage 6 evenings; brochure wording does not — read a quote · red flags · Stage 6.
Finance note: whole-home islands push CAPEX up; compare against phased essentials-first plus behavioural load control. A heat-pump, timers and a modest pack often beat a giant pack feeding a 3 kW geyser on backup every night — whole-home path · bond finance · geyser on backup · geyser overload.
After commissioning, log one week of Stage behaviour: SoC nadirs, any nuisance trips, and which circuits you still wish were on backup. Adjust boards before you buy more kWh — SoC · schedule strategy · expand later.
Estate and prepaid caveats
HOA rules may cap inverter size or battery placement even when your maths wants whole-home. Prepaid exporters may need conventional meters before the hybrid can behave as designed — fold those constraints into the brief early — estate / HOA · sectional title · prepaid migration · meter cost.
Also compare: hybrid vs off-grid · inverter sizing · usable kWh · aircon on battery · size a system hub.
If a partner cannot annex the backup circuit list, treat “whole house” as marketing and re-price an essentials-first hybrid with expansion headroom instead — expand later · choose installer.
Whole-house vs “everything important”
Most suburban hybrids island an essentials board, not every stove, geyser and pool circuit. True whole-house islands need continuous kW for coincidence peaks and usable kWh for the longest Stage — often three-phase and larger packs. Write which definition you want on the brief before comparing quotes — essentials · single vs three-phase · inverter size.
Thermal loads decide the budget
Geysers, ovens and large AC crush small packs. Move thermals to timers, heat-pumps or gas before you buy a second hybrid “just in case” — geyser on backup · heat-pump vs geyser · stove / oven · aircon.
Commissioning proof
At handover: kill the main, watch essentials stay up, restore grid, confirm reconnect delay and export limit. Photograph SoC, CT polarity and dual-supply labels — islanding · labels · CT clamps.
NMD and phase limits on “whole house”
Whole-house islands that include EV and cooking often collide with single-phase NMD before they collide with battery kWh. Price topology honestly — NMD / three-phase cost · Highveld derate · NMD.
Operate inside the warranty DoD and temperature window
Set the BMS limits to the warranty table you bought and keep the pack inside its temperature band. Heroic deep discharges and hot cupboards burn cycle life you already paid for. Monitoring alerts for low SoC and high temp go on your phone in week one.
Retest usable runtime after the first winter month and compare to the design brief.
Quick questions
Will a 5 kW hybrid run my whole house?
Unlikely if stove, geyser and kettle can start together. Measure coincidence, not nameplate dreams.
Is a bigger battery enough?
Battery stores energy; the inverter still limits instantaneous watts. You need both.
Can smart load shedding inside the house help?
Yes — contactors or hybrid load ports that drop geyser/oven first preserve the island.
Does whole-house backup change insurance?
Declare the system; some insurers care about lithium placement and electrical CoC — see insurance answers.
Sources & related
- Solar News 24 — essentials vs non-essentials
- Solar News 24 — Stage 6 battery
- Solar News 24 — hybrid vs off-grid