Best Solar Panel Capacity for Your Home: 1kW, 3kW, 5kW or 10kW?

Choosing the right system size is the difference between a 4-year payback and a 7-year payback. Too small and you keep paying the grid; too big and your subsidy is capped and excess generation goes underused. Here is how to nail the right capacity for your home.

The three numbers that decide your size

1. Your monthly electricity bill (units, not rupees)

Look at your last 3 bills and find the average units consumed per month. As a rule of thumb in India, 1 kW of solar generates ~120–140 units/month on average.

2. Your roof shadow-free area

Each kW needs roughly 80–100 sq ft of unshaded south-facing roof. Tilted RCC structures can fit slightly more density.

3. Your budget after subsidy

Up to 3 kW gets you the full ₹78,000 CFA. Beyond that, the extra capacity is a pure economic decision based on your usage.

Size guide for typical Indian homes

1 kW — small flats, 2-room homes

• Generates ~120 units/month
• Suitable if your bill is below ₹1,000/month
• Roof needed: ~100 sq ft
• Net cost after subsidy: ₹35,000–₹55,000

3 kW — most middle-class households (the sweet spot)

• Generates ~360–420 units/month
• Suitable if your bill is ₹2,000–₹4,000/month
• Roof needed: ~280–300 sq ft
• Net cost after subsidy: ₹97,000–₹1,42,000
• Best subsidy economics — full ₹78,000 CFA

5 kW — larger homes, AC-heavy use

• Generates ~600–700 units/month
• Suitable if your bill is ₹5,000–₹7,000/month
• Roof needed: ~450–500 sq ft
• Net cost after subsidy: ₹2,02,000–₹2,72,000

10 kW — kothis, farmhouses, joint families

• Generates ~1,200–1,400 units/month
• Suitable if your bill exceeds ₹8,000/month or you plan EV charging
• Roof needed: ~900–1,000 sq ft
• Net cost after subsidy: ₹4,62,000–₹6,02,000

Should you oversize for the future?

If you plan to buy an EV, install ACs in more rooms, or expand the family, oversizing by 20–25% is reasonable. Anything more than that and the surplus units may not get fully credited at year-end (depends on your state policy).

Don't size by bill rupees alone

Two homes paying the same ₹3,000/month can have very different unit consumption depending on their tariff slab. Always size by units, not by rupees — that is the engineering input.

Quick sizing formula

Required kW = (monthly units consumed × 12) ÷ 1,500

Example: a home using 400 units/month should install: (400 × 12) ÷ 1,500 = 3.2 kW. Round to 3 kW to maximise subsidy.

Need a precise sizing recommendation for your home? Send us your last 3 electricity bills and we will run the numbers for free.