What Size Solar System Do I Need for My Home? (kW Sizing Guide)
Quick answer: a good rule of thumb for Agra/UP homes is to divide your monthly electricity bill by about ₹1,000 to get your system size in kW. A ₹3,000 bill points to roughly a 3 kW system; a ₹5,000 bill to about 5 kW. Below is how to size it properly — by bill, by appliances, and by the roof space you actually have.
Method 1: Size by your electricity bill (easiest)
Your bill reflects your monthly units. In UP, at roughly ₹7 per unit for residential, and with Agra generation of about 120 units per kW per month, the shortcut works out cleanly:
- ₹1,500/month bill → ~1.5–2 kW (about 200 units/month)
- ₹2,500/month → ~2.5–3 kW
- ₹3,000/month → ~3 kW (the most popular home size, and where the ₹78,000 subsidy maxes out)
- ₹5,000/month → ~5 kW
- ₹8,000/month → ~8 kW
- ₹10,000+/month → 10 kW+
If you have a few months of bills, average them — summer (AC) months will be higher than winter, and you want the system sized for real annual use.
Method 2: Size by your appliances
If you're building a new home or don't have representative bills yet, add up your typical daytime load:
- 1.5-ton inverter AC: ~1.5 kW each
- Refrigerator: ~0.2 kW
- Ceiling fans (×4): ~0.3 kW
- Lights (LED, whole house): ~0.2 kW
- TV + Wi-Fi + chargers: ~0.2 kW
- Water pump (0.5 HP): ~0.4 kW
- Washing machine / microwave (occasional): ~1–1.5 kW when running
A home running two ACs plus normal load in the daytime typically wants a 5 kW system; one AC plus household load fits comfortably on 3 kW.
Method 3: Check your roof space
Whatever the bill suggests, you can only install what fits:
- You need roughly 80–100 sq ft of shadow-free roof per kW
- 3 kW → ~300 sq ft
- 5 kW → ~500 sq ft
- 10 kW → ~900–1,000 sq ft
RCC roofs, tin sheds and even open ground all work. If your ideal size doesn't fit, we prioritise the shadow-free area and size to that.
Two things that change the answer
Your sanctioned load. In UP, your rooftop system generally shouldn't exceed your sanctioned load without a load-enhancement application. If your ideal system is bigger than your sanctioned load, we file for enhancement — a routine step.
The subsidy sweet spot. The PM Surya Ghar subsidy caps at ₹78,000 for 3 kW and above. A 3 kW and a 5 kW system receive the *same* ₹78,000. So if your usage sits between 3–5 kW, 3 kW gives the best subsidy-per-rupee, while 5 kW covers heavier AC use — worth discussing based on your bills.
Can I start small and add more later?
Yes. Systems are modular — you can begin with 3 kW and expand as your load grows (a new AC, an EV charger). We design the structure and wiring with future expansion in mind when you tell us that's the plan.
The precise answer takes 10 minutes
These methods get you within half a kilowatt. For an exact size, use our [solar savings calculator](/solar-calculator) — enter your bill and it recommends the system size, cost, subsidy and savings instantly — or book a free survey and we'll size it against your actual roof and last 6–12 months of bills.