How Many Solar Panels Do I Need?
How Many Solar Panels Do I Need? (Kenya Examples & Calculations)
How Many Solar Panels Do I Need? One of the most common questions when planning a solar system is: “How many solar panels do I need to power my home or business? The answer depends on your daily power consumption, the wattage of the panels, and your location’s sunlight hours (Kenya averages 4–6 peak sun hours per day).
1. Factors That Determine the Number of Panels
- Your Daily Power Use (kWh):
- Add up the wattage of all appliances and how many hours you use them.
- Panel Wattage (W):
- Most modern panels are 350–550W.
- Sunlight Hours:
- Kenya averages 5 peak hours/day (Nairobi, Mombasa, Kisumu).
- System Efficiency:
- Account for 10–20% system losses (from inverter, cabling, etc.).
2. Quick Rule of Thumb
Number of Panels=Daily Power Use (Wh)Panel Wattage × Sun Hours × System Efficiency\text{Number of Panels} = \frac{\text{Daily Power Use (Wh)}}{\text{Panel Wattage × Sun Hours × System Efficiency}}Number of Panels=Panel Wattage × Sun Hours × System EfficiencyDaily Power Use (Wh)
3. Real-Life Examples
Example A – Small Home Setup (Lighting + TV + Fridge)
- Lighting: 6 LED bulbs × 10W × 6h = 360Wh
- TV: 1 × 100W × 4h = 400Wh
- Fridge: 1 × 120W × 10h = 1,200Wh
- Total = 1,960Wh ≈ 2kWh/day
With 350W panels: 2,000Wh÷(350W×5h×0.85)≈1.3 panels2,000Wh ÷ (350W × 5h × 0.85) ≈ 1.3 \text{ panels}2,000Wh÷(350W×5h×0.85)≈1.3 panels
Answer: 3 panels (350W each) for safety and cloudy days.
Example B – Medium Home (Lights + TV + Fridge + Freezer + Wi-Fi)
- LED lights: 10 × 10W × 6h = 600Wh
- TV: 100W × 5h = 500Wh
- Fridge: 120W × 10h = 1,200Wh
- Freezer: 150W × 8h = 1,200Wh
- Wi-Fi router: 20W × 12h = 240Wh
- Total = 3,740Wh ≈ 3.7kWh/day
With 350W panels: 3,700Wh÷(350W×5h×0.85)≈2.53,700Wh ÷ (350W × 5h × 0.85) ≈ 2.53,700Wh÷(350W×5h×0.85)≈2.5
Answer: 5–6 panels (350W each) for reliability.
Example C – Large Home (AC + Appliances + Entertainment)
- AC (1HP): 750W × 4h = 3,000Wh
- Lighting: 12 × 10W × 6h = 720Wh
- TV: 100W × 5h = 500Wh
- Fridge: 120W × 10h = 1,200Wh
- Microwave: 1,000W × 0.5h = 500Wh
- Total = 5,920Wh ≈ 6kWh/day
With 400W panels: 6,000Wh÷(400W×5h×0.85)≈3.56,000Wh ÷ (400W × 5h × 0.85) ≈ 3.56,000Wh÷(400W×5h×0.85)≈3.5
Answer: 8 panels (400W each).
Example D – Business (Shop + Freezers)
- Lighting: 6 × 10W × 10h = 600Wh
- Freezer 1: 150W × 10h = 1,500Wh
- Freezer 2: 150W × 10h = 1,500Wh
- POS + Router + Laptop: 120W × 8h = 960Wh
- Total = 4,560Wh ≈ 4.6kWh/day
With 400W panels: 4,600Wh÷(400W×5h×0.85)≈2.74,600Wh ÷ (400W × 5h × 0.85) ≈ 2.74,600Wh÷(400W×5h×0.85)≈2.7
Answer: 6–7 panels (400W each).
4. Pro Tips for Accurate Sizing
- Get a site assessment to avoid under or oversizing.
- Plan for future growth – add 1–2 extra panels if possible.
- Combine with the right inverter and battery for stable power.
- Consider efficiency losses (dust, shading, and heat can reduce output by 10–20%).
5. Key Takeaway
3–6 solar panels (350W each) can power a small Kenyan home with lighting, TV, and fridge.
For larger homes or businesses, you might need 8–12 panels depending on your energy needs.
