1Where is the system going?
2What must the system do?
Small home ≈ 300 · medium ≈ 600 · large ≈ 1000 kWh
⚙ Advanced — tariff, panel size, appliance detail
Eskom direct ≈ R2.71–2.90 (2026); municipal varies. Editable — payback uses this.
590 W is the current SA retail favourite
3Tick what must stay on
array ()
hybrid inverter
battery
installed est.*
Your 12 months of sun —
| Month | Sun (peak hrs/day) | Avg temp | Est. output* | Covers usage |
|---|
📋 Itemised estimate & payback
Adjust component pricing (installers: use your own rates)
🔧 Engineering detail (why these numbers)
Take this spec with you
Send it to yourself, an installer, or your partner — the link rebuilds this exact result.
Honest answers
- Why does everyone else’s calculator disagree?
- Most use annual-average sunshine. We size on your town’s worst month from 12 months of satellite data (ERA5), so June doesn’t embarrass your quote.
- What size system do I need for load shedding?
- Essentials (fridge, lights, Wi-Fi, TV, gate) run happily on a 3.6–5 kW hybrid with one 5.12 kWh battery and 4–6 panels. Run your own numbers above — takes a minute.
- Do panels work in winter?
- Yes, but expect 40–60% less than summer depending on region. Heat also trims panel output — our engine models both, per month.
- Which way should panels face in SA?
- True north, tilted ≈ your latitude. Add up to 15° if winter matters most — load-shedding season is winter.
- Can the battery carry my geyser?
- No — a 2 kW element empties a 5 kWh battery in ~2 hours. Geyser/stove/heater belong in the bill-offset plan (or gas/solar thermal).
- May I feed extra power back into the grid?
- Only as a registered SSEG generator with a NRS 097-compliant inverter. Your installer handles the application.
- Is this a quote?
- No. It’s a planning specification from public climate data and typical hardware prices. Get 2–3 quotes from qualified installers — a compliant install needs a COC.
- What will a 3.6 kW or 5 kVA inverter run during load shedding?
- Comfortably: fridge and freezer, lights, Wi-Fi, TV, laptop charging, alarm and gate motor together — that’s the essentials pack, about 870 W even if everything ran at once (they don’t). A kettle or microwave is fine for a couple of minutes. A geyser, stove or heater is a no — resistive heat flattens a battery in hours.
- How long will a 5 kWh battery last during load shedding?
- A 5.12 kWh LiFePO4 module delivers about 4.4 kWh usable after depth-of-discharge and inverter losses. Carrying a typical essentials pack that’s roughly 4–6 hours of a typical evening; discipline stretches it further (TV off, geyser never). Size the bank for the stage length you actually experience.
- How many solar panels for a 5 kVA inverter with battery?
- 5 kVA is about 4 kW continuous (0.8 power factor). With current 590 W panels, 6–9 panels (3.5–5.3 kWp) is typical so the battery still charges in winter. A DC-to-AC ratio of 1.2–1.4 is normal in South Africa because June output matters more than summer clipping.
- How much does a 5kW solar system cost in South Africa in 2026?
- Typical installed range is R80 000–R140 000 depending on panels, battery capacity and roof complexity. SunSizer builds an itemised estimate from current component pricing you can adjust.
- Is solar worth it in South Africa?
- Usually, but be honest about the goal. Backup-only systems protect your essentials from load shedding; at R3/kWh they often pay back in 9–14 years because they only offset the circuits they carry. Bill-offset systems sized on your real usage typically pay back in 4–8 years, faster every April as tariffs climb about 12% a year. Model both scenarios above and compare.
- kVA vs kW — what is the difference for solar?
- kW is real power doing work; kVA is apparent power — roughly kW divided by 0.8 for a typical home. South African inverters are marketed in kVA, so a “5 kVA” unit delivers about 4 kW continuous. Size the array and battery on your kWh needs and the inverter on your simultaneous watts.
Methodology (for the engineers)
- Data: ERA5 satellite-derived daily solar radiation & temperature, past 12 months, via Open-Meteo Archive API (CC BY 4.0, © ECMWF / Copernicus).
- Peak sun hours: radiation sum MJ/m² ÷ 3.6 → equivalent hours at 1 kW/m².
- Array energy: kWp × PSH × derate, per month. Derate = soiling 3% × mismatch 2% × DC wiring 2% × inverter 4% × AC wiring 0.5% × availability 1% × temperature factor.
- Temperature: cell ≈ ambient + 28 °C (flush roof); −0.34 %/°C from 25 °C — typical mono PERC.
- Battery: load ÷ (0.90 DoD × 0.96 inverter eff.), LiFePO4 51.2 V modules.
- Inverter: diversified continuous peak × 1.25, snapped to the SA retail ladder (3.6/5/6/8/10/12 kW single-phase, 16+ three-phase); motor-start surge checked against 2× rated (10 s).
- Excluded: shading, roof geometry, degradation (<0.6 %/yr — immaterial year one), tariffs escalation (payback shown flat; Eskom tariffs rose ≈12 %/yr average over the last decade).
- Not engineering advice. Final design, SSEG registration and COC by a qualified installer.