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From your monthly units to the number of panels and the roof area they need, worked out step by step for Raipur homes.
Image: Vermont Law School Solar Panel Array-2 by SayCheeeeeese, CC0, via Wikimedia Commons.
"How many solar panels do I need?" is the first practical question every homeowner asks, and the honest answer depends on your electricity use, not the size of your house. This guide gives you a simple method, a quick-reference table for typical homes and the roof area to expect, so that you can read a quotation with confidence. It is written for Raipur, where one kilowatt of well-installed capacity produces about 4.0 to 4.5 units a day on average.
Quick answer: a typical three-bedroom home using 300 to 400 units a month needs about 3 kW, which is six panels of around 540 Wp each, on roughly 30 square metres of shadow-free roof.
Round to a whole number of panels and check that the total capacity fits your sanctioned load and roof.
| System size | Panels at 540 Wp | Actual capacity | Roof area (approx.) | Monthly generation |
|---|---|---|---|---|
| 1 kW | 2 | 1.08 kW | 10 sq m | 120 - 135 units |
| 2 kW | 4 | 2.16 kW | 20 sq m | 240 - 270 units |
| 3 kW | 6 | 3.24 kW | 30 sq m | 360 - 400 units |
| 4 kW | 8 | 4.32 kW | 40 sq m | 480 - 540 units |
| 5 kW | 10 | 5.40 kW | 50 sq m | 600 - 675 units |
| 10 kW | 19 - 20 | 10.3 - 10.8 kW | 100 sq m | 1,200 - 1,350 units |
These are starting points only. Air conditioners, geysers, pumps and work-from-home use change the answer.
| Typical home | Typical monthly use | Likely system | Panels at 540 Wp |
|---|---|---|---|
| 1 BHK flat or small house | 100 - 150 units | 1 - 2 kW | 2 - 4 |
| 2 BHK home | 150 - 250 units | 2 kW | 4 |
| 3 BHK home | 250 - 400 units | 3 kW | 6 |
| 4 BHK or bungalow with ACs | 450 - 650 units | 5 kW | 10 |
| Large home with multiple ACs | 700+ units | 6 - 10 kW | 12 - 20 |
Roof area sets the upper limit, not the right size. A 100 square metre roof can host 10 kW, but if your family uses 250 units a month, 2 kW already covers the bill and extra panels earn little under net metering. Conversely, a small roof with heavy consumption may not fit the capacity you would like, in which case higher-wattage modules help. Match capacity to consumption first, then check that the roof can hold it.
Modules now range from around 440 Wp to over 600 Wp. Higher wattage lets you reach a target capacity with fewer panels, which helps on small roofs and reduces mounting hardware. The trade-off is larger physical size and sometimes higher cost per panel. What matters is price per watt, warranty and compliance with the scheme's module rules, covered in our guide to DCR modules and ALMM List-II.
A good quotation states the number of panels, the wattage of each, the total DC capacity, the inverter rating and the expected annual generation in units. If you divide the generation figure by capacity, you should land near 1,400 to 1,500 units per kW per year for Raipur. A number far above that suggests an optimistic estimate.
Example 1: a small flat. A couple in a two-bedroom flat uses 180 units a month, mostly fans, lights and a refrigerator. Daily use is about 6 units. Divide by 4.2 units per kW per day and you need about 1.4 kW, so a 2 kW system of four 540 Wp panels covers the bill with a margin and takes about 20 square metres.
Example 2: a family home with two air conditioners. A family of five uses 520 units a month in summer and 320 in winter, averaging 420 a year-round. Daily use is about 14 units. Divide by 4.2 and you need about 3.3 kW. Six panels give 3.24 kW, ten panels give 5.4 kW. The family chooses six panels for the bill and keeps the option to add four later.
Example 3: a home planning an EV. The same family adds an electric car that will use about 7 units a day. Total need rises to about 21 units a day, or about 5 kW. Ten panels at 540 Wp cover it. Read solar and EV charging at home for the details.
| Situation | Effect | What to do |
|---|---|---|
| Too few panels | A noticeable bill remains; payback still good but total saving smaller | Add capacity later if the roof and sanctioned load allow |
| About right | Most of the bill removed, surplus modest | Maintain and monitor |
| Too many panels | Surplus exported earns less; extra cost beyond subsidy cap | Size to consumption and keep headroom modest |
Because net metering banks surplus from one month to cover another, a slight oversize is rarely a disaster, but a large oversize wastes money. The simplest guard is to size from twelve months of bills and check the result with your installer.
Consumption in Raipur swings with the seasons. Summer air-conditioning can double a bill, while winter may show only fans and lighting. A single month's bill is misleading. Add all twelve months, divide by 365 and use the annual average as the basis, then check that the system can cover your peak months through banking. If your last year was unusual, for instance if the house was empty for months, adjust accordingly.
If your numbers and the installer's differ noticeably, ask them to show their assumptions. Differences usually come from the units-per-kW figure, shading allowance or a different view of future load, and each is easy to discuss once it is written down.
For cost, read solar panel price in Raipur. To see how a decision between two sizes plays out, read 3 kW vs 5 kW. Our overview of solar in Raipur covers savings and payback, and a local solar company in Raipur can confirm the count on site. Subsidy information is in PM Surya Ghar Yojana in Raipur, and our rooftop solar installation in Raipur service handles the work. If you are comparing providers, use our checklist for the best solar installer in Raipur. Households elsewhere in the state can read about solar in Chhattisgarh, choosing a solar company in Chhattisgarh, PM Surya Ghar Yojana in Chhattisgarh, solar subsidy apply online in Chhattisgarh and rooftop solar installation in Chhattisgarh.
With 540 Wp modules you need six panels for about 3.2 kW. With 550 Wp modules, six panels give about 3.3 kW. Panel wattage varies by model, so the count depends on the module chosen.
Plan about 10 square metres of shadow-free roof per kW, which allows for spacing between rows and access. A single 540 Wp panel measures roughly 2.3 by 1.1 metres, about 2.6 square metres.
A 540 Wp panel generates roughly 2.2 to 2.4 units on an average day in Raipur, or about 65 to 70 units a month, varying with season, shade and dust.
You can, but surplus beyond your consumption earns less under net metering and the central subsidy stops at 3 kW. Size to consumption, with headroom only if you expect a real increase such as an EV or air conditioner.
The panel count follows your daily energy need. A hybrid system may need slightly more capacity to charge the battery as well as run the house, which your installer should account for.
A calculation is a good start; a survey is the finish. Visit C-29, Sector 3, Devendra Nagar, Raipur, Chhattisgarh 492001, call 083051 31420 or book a free site survey and we will size panels to your bills and your shadow-free roof.
A good solar company in Raipur survey comes first. Read about solar in Raipur, compare firms with our best solar company in Raipur questions and see how solar installation in Raipur works in your solar Raipur neighbourhood. Browse every article on the solar blog, or see PM Surya Ghar Yojana in Raipur and our solar services.
Free survey, twelve-month bill analysis and a written layout with the panel count, from a Raipur solar team.