3 kW vs 5 kW Solar System — The Quick Answer
If your monthly electricity bill is ₹2,000–₹3,500 and you use 200–350 units/month, choose 3 kW. If your bill is ₹3,500–₹6,000 and you use 350–550 units/month (3 BHK with ACs), choose 5 kW. Here is the full comparison.
3 kW Solar System — Full Details
| Parameter | 3 kW System |
|---|---|
| Monthly generation (avg) | 300–390 units |
| Roof space needed | ~280–320 sq ft |
| Number of panels (400W) | 7–8 panels |
| Cost before subsidy | ₹1,70,000–₹2,10,000 |
| PM Surya Ghar subsidy | ₹78,000 |
| Effective cost after subsidy | ₹92,000–₹1,32,000 |
| Monthly savings (₹7/unit tariff) | ₹2,100–₹2,730 |
| Payback period | 3.5–5 years |
| Best for | 2–3 BHK, 200–350 units/month |
5 kW Solar System — Full Details
| Parameter | 5 kW System |
|---|---|
| Monthly generation (avg) | 500–650 units |
| Roof space needed | ~450–550 sq ft |
| Number of panels (400W) | 12–13 panels |
| Cost before subsidy | ₹2,80,000–₹3,50,000 |
| PM Surya Ghar subsidy | ₹78,000 (capped at 3 kW for subsidy) |
| Effective cost after subsidy | ₹2,02,000–₹2,72,000 |
| Monthly savings (₹7/unit tariff) | ₹3,500–₹4,550 |
| Payback period | 4–5.5 years |
| Best for | 3–4 BHK with ACs, 350–600 units/month |
Important: Subsidy Is Capped at 3 kW
PM Surya Ghar Yojana gives maximum ₹78,000 subsidy for 3 kW and above. This means going from 3 kW to 5 kW adds ~₹1,10,000–₹1,40,000 in cost with NO additional subsidy. The extra 2 kW costs you full market rate. Factor this into your decision.
When to Choose 3 kW
- Monthly bill under ₹3,500
- Small to medium home (2–3 BHK)
- Limited roof space (under 350 sq ft available)
- Want fastest payback and maximum subsidy benefit
- Single AC unit at home
When to Choose 5 kW
- Monthly bill above ₹3,500
- 3–4 BHK with 2+ ACs running daily
- Planning to add EV charging in future
- Work from home and use heavy appliances during daytime
- Available roof space of 450+ sq ft
Cost per kW — Is Bigger More Economical?
Solar systems have economies of scale. The cost per kW decreases as you go larger:
- 1 kW: ₹70,000–₹80,000 per kW
- 3 kW: ₹57,000–₹70,000 per kW
- 5 kW: ₹56,000–₹70,000 per kW
- 10 kW: ₹52,000–₹65,000 per kW
The per-kW savings between 3 kW and 5 kW are small — the decision should primarily be based on your consumption, not cost per kW.
Get Quotes for Your Home
The right size depends on your actual roof, consumption and local tariff. Get quotes from verified installers in your city:
- Solar installers in Bangalore
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- Solar installers in Chennai
Browse all residential solar installers on GoSolarIndex.