How to Choose Solar Panels According to Load
How to Choose Solar Panels According to Load?
Choosing the right solar panel system based on your energy load is crucial for maximizing savings and efficiency. Whether you're powering a home, office, or industrial setup, accurately calculating your daily energy consumption helps you select the optimal solar panel capacity. In this guide, we break down the process of calculating load, understanding peak sun hours, and determining how many solar panels you need. Perfect for beginners or business owners planning to shift to solar energy. This method ensures you get the right return on investment and avoid under- or over-sizing your system.
Step 1: Make a List of Appliances You Want to Run
Let’s say a customer wants to run:
| Appliance | Quantity | Power (Watts) | Usage per Day (Hours) | Total Watt-Hours/day |
|---|---|---|---|---|
| LED Bulb | 6 | 9W | 5 hrs | 6 × 9 × 5 = 270Wh |
| Fan | 2 | 75W | 6 hrs | 2 × 75 × 6 = 900Wh |
| TV | 1 | 100W | 4 hrs | 1 × 100 × 4 = 400Wh |
| Refrigerator | 1 | 150W | 24 hrs | 1 × 150 × 24 = 3600Wh |
| Mobile Charging | 2 | 10W | 2 hrs | 2 × 10 × 2 = 40Wh |
Total Daily Load = 270 + 900 + 400 + 3600 + 40 = 5210 Watt-hours (5.21 kWh/day)
Step 2: Adjust for Losses (Always Add 25–30%)
Due to wiring, inverter loss, temperature, panel angle, etc.
Total Load = 5.21 × 1.3 = ~6.8 kWh/day
Step 3: Find Average Sunlight Hours (PSH - Peak Sun Hours)
This depends on the region:
| Location | Avg. Sun Hours/day |
|---|---|
| India (Delhi, etc.) | 5 – 6 hrs |
| Iran | 5.5 – 6 hrs |
| Nigeria, etc. | 5 – 6 hrs |
Let’s assume 5 hours of sunlight.
Step 4: Calculate Total Solar Panel Size (Watt Capacity)
To determine how much solar panel capacity you need, use this formula:
Solar Panel Size (W) = Daily Load (Wh) ÷ Sunlight Hours (hrs)
Example:
Daily Load = 6800 Wh
Sunlight Hours = 5 hrs
Solar Panel Size (W) = 6800 ÷ 5 = 1360W ≈ 1.4kW
So, the customer will need at least 1.4kW of solar panels.
Step 5: Choose Panel Size and Quantity
Choose from common solar panel sizes such as 330W, 400W, or 550W.
If we choose 550W panels:
Required Panel Count = 1400 ÷ 550 ≈ 2.5 → round up → 3 panels
So, 3 × 550W = 1650W (1.65kW) solar panel system will be sufficient.
Summary
| Step | What You Do |
|---|---|
| 1 | List all appliances + usage per day |
| 2 | Multiply and total all watt-hours |
| 3 | Add 25–30% buffer |
| 4 | Divide by 5 (sunlight hours) |
| 5 | Choose right panel wattage and count |
FAQs
1. How do I calculate the load for my solar panel system?
Start by listing all electrical appliances, their wattage, and daily usage in hours. Multiply them to get total watt-hours (Wh) per day, then adjust for system losses.
2. How many solar panels do I need for a 5kWh daily usage?
If your area gets 5 hours of sun, divide 5000 Wh by 5 = 1000W (1kW). You’d need around 3×400W panels or 2×550W panels.
3. Does load calculation include future appliances?
Yes, always consider a 20–30% buffer for future usage or seasonal variation.
4. Can I use the same method for commercial solar panel sizing?
Absolutely. The formula remains the same — just the scale and energy needs will be larger.
5. What is the average sun hours for India or Iran?
On average, both countries get 5–6 peak sun hours per day.