The biggest question homeowners ask before switching to solar energy is — “How many solar panels do I need for my house?” The answer depends on your electricity usage, roof size, sunlight hours in your location, and the wattage of solar panels.
With solar power adoption growing rapidly in India, the U.S., and across the world, understanding the right number of panels helps in planning your budget, choosing the right system size, and maximizing long-term savings. In this blog, we’ll break down the calculation process, provide real-life examples, and answer common FAQs so you can make an informed decision.
🔹 Factors That Affect the Number of Solar Panels
- Your Monthly Electricity Consumption
- Measured in kilowatt-hours (kWh).
- Example: An average Indian household consumes 250–350 kWh/month.
- Solar Panel Wattage
- Standard solar panels come in 250W, 350W, and 450W.
- Higher wattage panels require fewer units.
- Peak Sunlight Hours in Your Area
- Affects how much energy panels can produce daily.
- Example: Delhi = ~5.5 hours/day, Mumbai = ~4.5 hours/day.
- Roof Size and Orientation
- Panels need proper tilt and shade-free installation.
- Approx. 100 sq. ft. roof space = 1 kW solar capacity.
- Energy Goals
- Do you want to cover 100% of your bill, or just partial savings?
🔹 Step-by-Step Calculation
Let’s say:
- Your monthly usage = 300 kWh
- Daily usage = 300 ÷ 30 = 10 kWh/day
- Location = Delhi (5.5 sunlight hours)
- Panel size = 350W (0.35 kW)
Step 1: Energy per panel = 0.35 kW × 5.5 hours = 1.925 kWh/day
Step 2: Panels needed = 10 ÷ 1.925 ≈ 5.2 panels
👉 So, you’ll need 6 panels of 350W each for your home.
🔹 Quick Reference Table
| Home Size | Avg. Power Need (kWh/day) | No. of Panels (350W) | Roof Space Needed |
|---|---|---|---|
| 1 BHK Flat | 5–6 kWh | 3–4 panels | 400 sq. ft. |
| 2 BHK Flat | 10–12 kWh | 6–7 panels | 600 sq. ft. |
| 3 BHK House | 15–18 kWh | 8–10 panels | 900 sq. ft. |
| Farm House (Large) | 30–40 kWh | 15–20 panels | 2000 sq. ft. |
(Note: These are average estimates. Actual numbers may vary.)
🔹 Solar Panel Wattage Comparison
| Panel Wattage | Energy Produced (per day, 5 hrs) | Panels Needed for 10 kWh/day |
|---|---|---|
| 250W | 1.25 kWh | 8 panels |
| 350W | 1.925 kWh | 6 panels |
| 450W | 2.25 kWh | 5 panels |
👉 Choosing higher wattage panels reduces the number of units needed.
🔹 Cost Estimation (India, 2025)
| System Size | No. of Panels | Approx. Cost (₹) | Subsidy (20–40%) | Final Price (₹) |
|---|---|---|---|---|
| 2 kW | 6 panels | ₹1,20,000 | ₹24,000–₹48,000 | ₹72,000–₹96,000 |
| 3 kW | 9 panels | ₹1,80,000 | ₹36,000–₹72,000 | ₹1,08,000–₹1,44,000 |
| 5 kW | 15 panels | ₹3,00,000 | ₹60,000–₹1,20,000 | ₹1,80,000–₹2,40,000 |
(Source: MNRE subsidy scheme, India)
🔹 Common Mistakes to Avoid
- Ignoring future electricity needs (EVs, appliances).
- Buying panels without checking roof orientation and shading.
- Choosing low-quality inverters or batteries.
- Not applying for government solar subsidy.
- Believing that “more panels = better” without checking wattage.
🔹 Future Scope – Why Calculate Properly?
With rising electricity bills and the increasing popularity of EV charging at home, homeowners must plan for at least 20–30% extra capacity. Correct panel calculation ensures your system supports future needs without overspending.
🔹 FAQs
Q1: How many solar panels do I need for a 1,000 sq. ft. house?
👉 Typically 8–12 panels depending on usage and panel wattage.
Q2: How many solar panels are required for a 5 kW system?
👉 Around 12–15 panels (350–450W each).
Q3: Do I need batteries with solar panels?
👉 Not always. Batteries are required only for backup or off-grid systems. Grid-tied systems don’t need them.
Q4: Can solar panels run ACs and refrigerators?
👉 Yes. With a properly sized system (3 kW+), you can easily run ACs, fridges, lights, and fans.
Q5: How long do solar panels last?
👉 25–30 years with 80%+ efficiency guaranteed by most manufacturers.
Q6: Will more panels reduce my bill to zero?
👉 Not always. It depends on net metering rules, sunlight, and system size.
Q7: Is roof direction important?
👉 Yes. South-facing roofs (in India) get maximum sunlight.
🔹 Conclusion
Calculating the right number of solar panels for your home ensures you save money, maximize efficiency, and future-proof your energy needs. For most households, a 2–5 kW system (6–15 panels) is sufficient to cut down 70–100% of electricity bills.
If you’re planning to install solar, start by checking your monthly usage, choosing the right panel wattage, and applying for government subsidies. Switching to solar is not just about saving money—it’s about contributing to a sustainable future.
