1) Map your needs (what must stay on?)
List the circuits/devices that must run during load-shedding: lights, Wi-Fi, TV, fridge/freezer, a few plugs for laptops or routers. Ignore large resistive loads (geyser, oven, heater) in a starter system — they demand big inverters and batteries.
| Device | Power (W) | Hours/day | Energy (Wh) |
|---|---|---|---|
| LED lights (whole house) | 120 | 5 | 600 |
| Wi-Fi & router | 20 | 18 | 360 |
| TV + decoder/box | 120 | 3 | 360 |
| Fridge/freezer (average) | 80 | 24 | 640 |
| 2 x laptops | 120 | 4 | 480 |
| Subtotal | 2 440 Wh ≈ 2.44 kWh |
Add 20–30% headroom for surges and “real life” usage: ≈ 3.0–3.2 kWh/day for essentials. Whole-home backup might be 8–15 kWh/day.
2) Right-size the battery (for hours of backup)
South African load-shedding blocks are often 2–4 hours. If you want to ride out two blocks without sun, plan for 5–8 hours of autonomy.
- Battery energy needed = daily essential load × desired hours ÷ 24
- Example: 3.2 kWh/day × 8 h ÷ 24 ≈ 1.07 kWh minimum — but that’s thin for fridge cycling and peaks.
In practice, most homes start with 5–10 kWh LiFePO₄ (e.g., 1× 5 kWh or 2× stacked to 10 kWh). LiFePO₄ offers long cycle life, high usable depth of discharge (90–100%), and good warranties.
3) Pick an inverter (hybrid recommended)
A hybrid inverter can blend solar, grid and battery. Popular sizes:
- 5 kVA / 5 kW — common sweet spot for small–medium homes.
- 8–10 kVA — larger houses or if you’ll run heavier appliances.
Look for: parallel/stacking support, PV input voltage window, MPPT current, warranty, and a local support channel. Hybrid inverters also simplify daytime self-consumption.
4) Size your panels (match energy, not just power)
South African insolation gives roughly 4.5–6.0 “sun hours” equivalent per day (location/season dependent). To estimate energy yield:
Daily kWh ≈ Array kW × sun hours × 0.75 (losses)
- Example: 3.3 kW array (6 × 550 W) × 5.0 × 0.75 ≈ 12.4 kWh/day
That easily covers a 3 kWh essential load plus battery charging. If you want to offset more of your total household usage, scale panels accordingly (space, budget and inverter PV limits permitting).
5) Protection & balance of system
- Combiner/isolators, DC fuses/breakers, PV surge protection (DC & AC).
- Correct cable sizing, lugs, trunking, and earthing per SANS.
- Battery communications cable (CAN/RS485) for BMS-to-inverter integration.
- Compliance: COC and, where applicable, municipal/utility registration.
What will it cost (ballparks)?
| Tier | Typical spec | Ballpark hardware* |
|---|---|---|
| Starter essentials | 5 kVA hybrid + 5 kWh LiFePO₄ + 6 × 550 W | R65 000–R95 000 |
| Comfort | 5–8 kVA + 10 kWh + 8–10 panels | R95 000–R160 000 |
| Whole-home (most loads) | 8–10 kVA + 15–20 kWh + 12–16 panels | R160 000–R300 000+ |
* Hardware only, typical online pricing; installation, CoC and compliance vary by site.
FAQ
Do I need to replace my DB board?
Not necessarily. Many installs use a dedicated essential-loads sub-DB. Your installer will advise based on wiring and space.
Can I add more batteries/panels later?
Yes — choose an inverter and battery brand that supports parallel expansion and check PV input limits for future strings.
What about geysers and ovens?
They are high-draw. Either keep them on grid, fit a heat pump/solar-thermal for hot water, or size a larger system with realistic budget.
This guide is informational and not a substitute for a site survey or professional design. Always use a qualified electrician and comply with local regulations.