How Many Solar Panels Do I Need?

Calculate the exact number of solar panels for your home. Based on your electricity bill, roof space, and solar goals.

The number of solar panels you need depends on your electricity usage, roof space, and what you want to achieve. This guide shows you how to calculate your exact requirements.

Quick Answer by Home Size

home	monthly Usage	panels	system Size
Small (1-2 bedroom)	400-600 kWh	4-6 panels	2-3 kW
Medium (3 bedroom)	600-900 kWh	8-10 panels	4-5 kW
Large (4 bedroom)	900-1200 kWh	10-14 panels	5-7 kW
Very Large (5+ bedroom)	1200+ kWh	14-20+ panels	7-10+ kW

homeSmall (1-2 bedroom)

monthly Usage400-600 kWh

panels4-6 panels

system Size2-3 kW

homeMedium (3 bedroom)

monthly Usage600-900 kWh

panels8-10 panels

system Size4-5 kW

homeLarge (4 bedroom)

monthly Usage900-1200 kWh

panels10-14 panels

system Size5-7 kW

homeVery Large (5+ bedroom)

monthly Usage1200+ kWh

panels14-20+ panels

system Size7-10+ kW

Step-by-Step Calculation

Calculate your exact needs:

1. Find your monthly kWh usage (on your electricity bill)
2. Calculate daily usage: monthly ÷ 30
3. Calculate system size: daily kWh ÷ 4.5 (average SA sun hours)
4. Calculate panels: system kW ÷ 0.55 (for 550W panels)
Example: 900 kWh/month ÷ 30 = 30 kWh/day ÷ 4.5 = 6.7 kW ÷ 0.55 = 12 panels

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Factors That Affect Panel Count

Considerations that change requirements:

Roof direction: North-facing is ideal. East/West need 10-15% more panels.
Shading: Trees or buildings blocking sun? Need more panels or different layout.
Panel wattage: 550W panels need fewer than 400W panels.
Goals: 100% offset vs 50% vs load shedding backup only?
Future usage: Electric vehicle? Growing family? Size up.
Budget: Can add panels later if inverter is sized correctly.

Panels by Coverage Goal

goal	coverage	panels
Load shedding backup only	30-40%	4-6 panels
Reduce bill meaningfully	50-60%	6-10 panels
Near self-sufficiency	70-80%	10-14 panels
Full energy independence	100%+	14-20+ panels

goalLoad shedding backup only

coverage30-40%

panels4-6 panels

goalReduce bill meaningfully

coverage50-60%

panels6-10 panels

goalNear self-sufficiency

coverage70-80%

panels10-14 panels

goalFull energy independence

coverage100%+

panels14-20+ panels

Roof Space Requirements

panels	roof Space	dimensions
6 panels	15m²	Approx 5m x 3m
10 panels	25m²	Approx 5m x 5m
14 panels	35m²	Approx 7m x 5m
18 panels	45m²	Approx 9m x 5m

panels6 panels

roof Space15m²

dimensionsApprox 5m x 3m

panels10 panels

roof Space25m²

dimensionsApprox 5m x 5m

panels14 panels

roof Space35m²

dimensionsApprox 7m x 5m

panels18 panels

roof Space45m²

dimensionsApprox 9m x 5m

Price Disclaimer: Prices shown were verified on 29 January 2026. Prices may change without notice. We earn affiliate commissions on qualifying purchases.

All prices are in South African Rand (ZAR) unless otherwise stated. Shipping costs may apply depending on your location.

Solar Panel Prices System Sizing Guide 5kW Systems

How Many Solar Panels Do I Need? FAQs

For the average 3-bedroom SA home using 800-1000 kWh/month, you need 8-12 solar panels (550W each) to cover 60-80% of your electricity. For full coverage including geyser and high-demand appliances, 14-18 panels. For essentials-only backup, 6 panels is sufficient.

A 5kW system requires 9-10 panels of 550W each. Some installers over-panel slightly (10-11 panels) to maximize generation during non-peak hours, which is beneficial and common practice.

Major retailers: Builders Warehouse, Makro, Takealot. Solar specialists: SolarShop, Sustainable.co.za, The Solar Warehouse. Always compare prices and check warranty support before buying.

For grid-tied systems, yes - you need a qualified electrician with COC (Certificate of Compliance). For simple off-grid setups, DIY is possible but not recommended. Poor installation is the #1 cause of solar system failures.

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