How to Size Your Solar System for Your Lagos Home

Why Proper Sizing Matters

Installing a solar system that's too small means frequent power shortages. Too large, and you've wasted money on unnecessary capacity. Proper sizing ensures you get exactly what you need—no more, no less.

Step 1: Calculate Your Daily Power Consumption

Start by listing all appliances you want to power and their wattage:

Typical Lagos Home Appliances:

• Refrigerator: 150W (runs 24/7) = 3,600Wh/day
• LED TV (43"): 60W × 6 hours = 360Wh/day
• Ceiling fans (4): 75W × 8 hours = 600Wh/day
• LED bulbs (10): 10W × 6 hours = 600Wh/day
• Laptop charger: 65W × 4 hours = 260Wh/day
• Phone chargers (4): 10W × 3 hours = 120Wh/day
• Standing fan: 50W × 8 hours = 400Wh/day

Total daily consumption: 5,940Wh (≈ 6kWh/day)

Step 2: Determine Required Solar Panel Capacity

Lagos receives an average of 5-6 peak sun hours daily. To generate 6kWh/day:

Formula: Daily consumption ÷ Peak sun hours × 1.25 (efficiency loss)

Calculation: 6,000Wh ÷ 5.5 hours × 1.25 = 1,364W

Recommended panel capacity: 1.5kW (1,500W)

Panel Configuration Options:

• Option A: 6 × 250W panels = 1,500W
• Option B: 5 × 300W panels = 1,500W
• Option C: 4 × 400W panels = 1,600W (recommended for future expansion)

Step 3: Size Your Battery Bank

Battery capacity determines how long you can run on stored power without sunlight (nighttime, cloudy days).

Formula: (Daily consumption × Days of autonomy) ÷ (Battery voltage × Depth of discharge)

For 2 Days of Backup:

(6,000Wh × 2) ÷ (24V × 0.5) = 1,000Ah at 24V

Battery Options:

• Lead-acid (Tubular): 4 × 250Ah 12V batteries (wired for 24V) = ₦400,000
• Lithium (LiFePO4): 1 × 1000Ah 24V battery = ₦1,200,000 (longer lifespan, 80% DoD)

Step 4: Choose the Right Inverter

Your inverter must handle your peak load (highest simultaneous power draw).

Peak Load Calculation:

• Refrigerator startup: 450W
• 4 fans: 300W
• TV: 60W
• 10 lights: 100W
• Laptop: 65W
• Total peak: 975W

Recommended inverter: 1.5kW (1,500W) with 25% overhead for surge capacity

Complete System Example: 2-Bedroom Lagos Apartment

System Components:

• Solar panels: 5 × 300W = 1,500W (₦450,000)
• Inverter: 1.5kW hybrid inverter (₦280,000)
• Batteries: 4 × 250Ah tubular batteries (₦400,000)
• Charge controller: 60A MPPT (₦80,000)
• Mounting & wiring: (₦120,000)
• Installation: (₦150,000)

Total system cost: ₦1,480,000

Sizing for Different Home Types

Studio/1-Bedroom (Light Use):

• Daily consumption: 3-4kWh
• Panel capacity: 1kW
• Battery: 400Ah at 24V
• Inverter: 1kW
• Estimated cost: ₦800,000 - ₦1,000,000

3-Bedroom (Heavy Use + AC):

• Daily consumption: 12-15kWh
• Panel capacity: 3kW
• Battery: 1,600Ah at 48V
• Inverter: 5kW
• Estimated cost: ₦2,500,000 - ₦3,500,000

Common Sizing Mistakes to Avoid

1. Underestimating consumption: Always add 20% buffer for future appliances
2. Ignoring surge power: Some appliances (fridges, pumps) need 3x their rated power at startup
3. Skimping on batteries: Undersized batteries mean frequent deep discharge, shortening lifespan
4. Wrong panel orientation: Panels should face south for maximum Lagos sun exposure
5. Ignoring shading: Even partial shade drastically reduces panel output

Get a Professional Assessment

While this guide provides a solid foundation, every home is unique. Professional installers will:

• Conduct on-site energy audits
• Measure actual consumption with meters
• Assess roof suitability and shading
• Recommend optimal component brands
• Design custom wiring and mounting

Ready for a custom system design? Get free quotes from verified Lagos installers in 2 minutes.