EV + solar
How much solar and battery do I need for a cheap EV commute?
Updated 27 October 2026
Answer first: For South Africa’s cheapest new EVs (Geely E2-class ~39 kWh, Chery Q-class ~43 kWh), a 2–3 kWp panel add-on plus roughly 7–10 kWh usable battery can cover a typical ~40–50 km weekday commute if you charge from the pack overnight — on the order of the ~R42 000 hardware sketch MyBroadband published in October 2026. Your real number moves with finance rate, existing inverter capacity, CoC/SSEG costs and whether you can charge in daylight instead.
Daily energy, not showroom range
WLTP range sells cars; kWh/day sizes solar. A 45 km round trip at 13 kWh/100 km is about 6 kWh at the wheels; with charge losses budget 6.5–7.5 kWh/day. Johannesburg winter and Pretoria heat both nudge that up. Long weekend trips belong on public DC math, not on the home pack.
Bill of materials that usually appears
| Building block | Starting point | Watch-outs |
|---|---|---|
| PV | 1.7–3.0 kWp dedicated to EV refill | Roof space, shading, existing string room |
| Battery | ~7–10 kWh usable | Must match inverter protocol list |
| Inverter | Use existing hybrid if ports allow | Else add 3–5 kW class machine + finance |
| Wallbox | 7.4 kW single-phase with solar mode | CoC, load management, estate rules |
| Compliance | CoC + SSEG if grid-tied | Not inside glossy hardware carts |
Finance is the silent tariff
Hardware at R40–50 k looks small next to a R340 k car — until you put it on a 20% personal loan. A green home-loan top-up or cash changes the monthly total more than swapping panel brands. See solar finance and the worked MyBroadband case in our R7 307/month news piece.
When you can skip the extra battery
If you park at work with daytime AC, or can schedule home charging under strong midday PV with the car present, you may enlarge the array and skip a dedicated EV battery — provided the hybrid can throttle the wallbox to surplus. Most nine-to-five commuters cannot; they need overnight energy already stored.
Worked commute examples (illustrative)
| Daily distance | Approx. kWh/day at charger | PV + battery starting point |
|---|---|---|
| 30 km | ~4–5 kWh | 1.5–2 kWp + ~5 kWh usable |
| 45 km | ~6.5–7.5 kWh | 2–3 kWp + ~7–8 kWh usable |
| 70 km | ~10–12 kWh | 3–4 kWp + ~10–14 kWh usable (or workplace AC) |
These are design seeds, not quotes. Coastal humidity, Highveld winter mornings and hilly routes all move consumption. Log two weeks of trip-computer kWh before you sign a variation order.
Estate, sectional title and DIY traps
Shared parking kills many “cheap EV + cheap solar” plans. If the car sleeps underground, rooftop PV on your unit may not reach the bay without body-corporate reticulation. Budget governance time equal to hardware time. DIY wallbox installs without a CoC are how insurers walk away after a DB fire — the savings on labour vanish in one declined claim.
Second-hand EVs need the same energy maths plus a charger-port and onboard-charger health check. A bargain car with a tired pack is not a R7 307 story; it is a different spreadsheet. See second-hand EV readiness.
Order of spend that usually protects savings
- Measure weekly kWh and tariff name.
- Wallbox + CoC on a dedicated circuit.
- Load shifting / solar mode on existing PV.
- Add PV kWp if midday surplus is thin.
- Add battery only for the overnight gap you still cannot cover.
Skipping straight to a large battery because a short video said “Stage 6” is how cheap-EV maths turns expensive. Deeper pillar: EV charging guide; finance: solar finance.
Prepaid and TOU households
Token meters and Homeflex clocks change the overnight story. A wallbox that yanks 7 kW through the expensive window can erase solar gains even when the monthly average looks fine. Schedule charging into off-peak or solar-surplus modes, and keep a separate eye on fixed charges that never leave the bill. More: TOU / prepaid EV, Homeflex Gen-offset.
Compatibility and compliance checklist
Before the deposit leaves your account, tick: inverter–battery pairing PDF, wallbox load-management feature, dedicated breaker and cable CSA on the drawing, dual-supply labels if the hybrid islands, SSEG path named for your metro or Eskom Direct, and a workmanship warranty that covers roof penetrations. Cheap-EV maths dies when a R8 000 re-inspection or a declined insurance claim arrives in month two.
Prefer AC chargers that can follow solar surplus so midday kWh never become weak export credits. If the estate will later demand OCPP for billing, do not buy a sealed dumb unit. Brand roundup: home charger brands; wiring: wiring & CoC.
Panel degradation and inverter mid-life belong in the seven-year finance story. Knock a conservative half-percent a year off yield in the spreadsheet and park an inverter reserve. That habit keeps the “petrol-free” claim honest when the car loan ends and the solar kit is what actually makes kilometres cheap.
Peers to open beside this page: R7 307 worksheet news, BEV sales surge, 5 kW system cost.
What a good installer quote must show
Insist on separate lines for: PV kWp and panel model, battery usable kWh and cycle warranty, inverter model and firmware note, wallbox model, DB/CoC labour, SSEG application fee if any, and contingencies. A single “EV solar package R85 000” blob hides whether you are paying for theatre capacity you will never cycle. Ask for a weekday charging schedule tied to your tariff windows.
If the quote assumes 100% solar-powered kilometres in June on the Highveld without a weather derate, send it back. Honest designs show grid import in winter and still beat petrol. Keep the MyBroadband R42 k sketch as a hardware peer for the commute-only slice — your whole-home backup ambitions are a different budget line and should be priced that way.
Quick savings test before you buy
Take last month’s petrol spend for the car you will replace. Subtract projected home charging cost at your tariff for the same kilometres (use 14 kWh/100 km as a cautious EV figure if you lack data). If the gap does not cover the solar-kit instalment after a realistic interest rate, shrink the kit or wait for a cheaper finance channel — do not inflate panel count to decorate the roof.
When the gap is wide, lock the wallbox and CoC first so every grid kWh still undercuts fuel while the PV quote matures. That sequencing has saved more SA households money than any “buy everything in one exciting weekend” bundle.
Related
Do not let the car steal the house’s payback
Size usable battery kWh to fridge, lights, routers, medical devices and the Stage length you actually get. Put the wallbox on a controllable non-essential so a 7.4 kW charge session cannot flatten the pack when the grid drops. Midday PV → EV is the cheap mile; overnight grid-charge on a steep block is how “solar car” maths quietly fails.
Illustrative: 30 kWh/week of home charging at R2.80 solar-midday equivalent vs R5.50 public-DC-ish effective cost is hundreds of rand a month — but only if the hybrid still covers the house. Related: charge from solar · Stage 4 battery · EV load management.
Miles first, then kWh sticker
Convert weekly km → kWh at the wall (include charger losses), decide how many of those kWh should come from daytime PV vs overnight TOU, then size battery for house Stage essentials separately from EV miles. Mixing “the battery will charge the car through Stage 6” into a small hybrid brief is how quotes fail on week one.
Related: EV from solar · charger cost · TOU / prepaid EV.
Sources
- MyBroadband Geely E2 + solar worksheet, 16 Oct 2026.
- naamsa / MyBroadband BEV sales context, Sep 2026 reporting.
Public DC as a pressure valve
If home battery cannot cover rare long trips, price a monthly public DC budget (SAEV Richmond-class battery-backed DC among GridCars / Chargify / Eskom mall peers — confirm live tariffs) instead of oversizing the home pack for the 5th percentile journey — public networks · public vs home cost.
Workplace charging as a third lever
If the employer offers daytime charging, home battery can shrink toward house Stage needs while the car drinks workplace solar or tariff energy — check fringe-benefit rules — workplace charging · SARS fringe benefit.