Savings8 min read
How Many Solar Panels Do You Need for a ₹3,000 Electricity Bill?
Forget panel counts - size from units. This guide converts your monthly bill into kW, panel count, roof area and net price for Ahmedabad homes.
The right way to size rooftop solar is not "how many panels" but how many units you consume. Panel wattage changes every year; your consumption does not. Here is the conversion, with Ahmedabad numbers.
The simple sizing formula
- Take your average monthly units from the last twelve bills (not just the summer peak).
- Divide by 120 units per kWp per month - Gujarat's typical yield at about 4 units/kWp/day.
- Round to the nearest available system size, allowing for future load like an AC or EV.
Example: a bill of about ₹3,000 in Ahmedabad usually corresponds to roughly 300 units a month. 300 ÷ 120 ≈ 2.5 kWp - and because the ₹78,000 subsidy caps at 3kW, most homeowners in this band choose a 3.3 kWp system so nothing is left on the table.
Bill to system size to panel count
| Monthly units | Approx bill | System size | Panels (~540 Wp) | Shadow-free roof |
|---|---|---|---|---|
| ~200 units | ~₹1,800 – ₹2,200 | 1.5 – 2 kWp | 3 – 4 | ~130 – 170 sq ft |
| ~300 units | ~₹2,700 – ₹3,200 | 2.5 – 3.3 kWp | 5 – 6 | ~200 – 250 sq ft |
| ~400 units | ~₹3,500 – ₹4,200 | 3.3 – 3.85 kWp | 6 – 7 | ~250 – 300 sq ft |
| ~500 units | ~₹4,500 – ₹5,200 | 4.4 kWp | 8 | ~330 sq ft |
| ~700 units | ~₹6,000 – ₹7,000 | 5.5 – 6 kWp | 10 – 11 | ~450 sq ft |
Panel counts assume roughly 540 Wp modules; with higher-wattage modules you need fewer. This is exactly why sizing in kWp, not panels, is the meaningful conversation.
What a 1kW system generates per day
In Ahmedabad, about 4 units per day on average across the year - higher on clear winter days, lower during monsoon weeks. Over a month that is roughly 120 units per kWp, which is the multiplier used throughout this guide.
Cost for the common sizes
| System | Price | Net payable | Est. monthly units |
|---|---|---|---|
| 3.3 kWp | ₹1,64,000 | ₹86,000 | ~396 |
| 3.85 kWp | ₹1,88,800 | ₹1,10,800 | ~462 |
| 4.4 kWp | ₹2,14,500 | ₹1,36,500 | ~528 |
Should you size for 100% of your bill?
Usually aim to cover 80–100% of annual consumption. Oversizing beyond your sanctioned load triggers DISCOM approvals, and export beyond your annual consumption earns less than it saves. Undersizing, on the other hand, leaves you buying units from the DISCOM for 25 years - the more expensive of the two errors. Read 3kW vs 5kW for the judgement call.
Put your own bill into the solar cost calculator for a size and savings estimate, see the money side in the savings breakdown, then get a free quote with the sizing confirmed against your last twelve bills.
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Related reading
- How Much Can You Save With Solar in Ahmedabad? Real Savings Breakdown
How much does solar actually save on an Ahmedabad electricity bill? We walk through real before/after numbers, payback timelines and a 25-year projection using real system prices.
- 3kW vs 5kW Solar System: Which Should You Buy?
The subsidy caps at 3kW, but the cheapest capacity you will ever buy is the extra kW added on day one. Here is how to decide between a 3kW and a 5kW system.
- 1kW to 5kW Solar System Price in Ahmedabad: Which Size Do You Need?
Not sure whether you need a 2kW, 3.3kW or 4.4kW system? Here is how to size solar for your Ahmedabad home based on your actual electricity bill, plus real pricing at each size.