NoteMide India rooftop solar planning guide

How Many Solar Panels Do I Need for a ₹4,000 Electricity Bill?

A ₹4,000 electricity bill does not map to one universal solar-panel number. The answer depends on the unit rate behind the bill, fixed charges, monthly consumption, the share of the bill you want solar to offset, panel wattage, roof space, shade, and the rules for exporting surplus electricity. A transparent estimate starts with units rather than guessing from the rupee amount.

Start by converting the bill into units

If the usable energy charge is approximately ₹8 per unit, a ₹4,000 monthly bill suggests about 500 units before fixed charges, taxes, arrears, and slab effects are separated. The simple calculation is ₹4,000 ÷ ₹8 = 500 units per month. At ₹10 per unit, the same bill suggests about 400 units; at ₹6 per unit, it suggests about 667 units. This is why the tariff field in the NoteMide calculator is editable. For a better estimate, read the monthly units or kWh printed on several recent bills. Use a typical month or an annual average instead of a single unusually hot or low-use month.

Translate annual use into a preliminary system size

A planning estimate can use roughly 1,200 units of annual generation per installed kW as a starting assumption. At 500 units per month, annual use is about 6,000 units. An 80% offset target is 4,800 units per year; 4,800 ÷ 1,200 suggests about a 4 kW system before roof and site limits. A 100% target would suggest about 5 kW under the same simplified assumption. Solar yield changes with location, roof orientation, tilt, shade, dust, weather, equipment, downtime, and system losses.

Convert kilowatts into panel count

Panel count depends on panel wattage. A 4 kW system using 550 W panels needs ceiling(4,000 ÷ 550), or about 8 panels. Using 400 W panels, the same nominal system needs 10 panels. Layout gaps, walkways, parapets, shade setbacks, inverter placement, and access paths also matter. As a rough planning check, about 100 square feet per kW of usable roof area means a 4 kW scenario may need around 400 square feet, but the actual layout must be measured on site.

Why your bill may not become zero

Solar generation offsets energy use, but a connection can still have fixed charges, taxes, minimum charges, demand charges, or export-settlement rules. Net metering and other export arrangements vary by state, DISCOM, consumer category, sanctioned load, system size, and the current regulation. Batteries change the economics and are not included in this simple estimate. Ask an installer to state equipment, generation assumptions, approvals, metering, warranty, and total installed price.

A worked ₹4,000 example

Suppose the typical monthly bill is ₹4,000, the editable planning tariff is ₹8 per unit, the target offset is 80%, the roof has 600 square feet of usable area, and the panels are 550 W. The simple estimate begins with 500 units per month, 6,000 units per year, and a 4,800-unit target. That points toward a preliminary 4 kW system and about 8 panels, subject to the roof and the actual generation model. This is planning math, not a subsidy approval, engineering design, vendor quote, or net-metering decision.

Official sources and related tool

Open the NoteMide Rooftop Solar Calculator · PM Surya Ghar National Portal · MNRE rooftop solar programme

Updated 2026-11-04 · Maintained by NoteMide. Subsidy, tariff, metering and policy details can change; verify the live official source before making a purchase or application.