Solar Panel Size Calculator (2026)

Add your air conditioners and other load, pick your state, and get the solar system size in kW, panel count, shadow-free roof area and installed cost — with the PM Surya Ghar subsidy applied.

Sizes all your ACs together State-wise sun hours Free · no sign-up

Step 1 — Your air conditioners

We use the average running draw for the tonnage and BEE star rating — not the scary nameplate watts.

Step 2 — Sunlight in your region

Other monthly consumption (units, optional) Everything on your bill that isn't the ACs above. Leave blank to size for the ACs only.

Advanced

Panel wattage (Wp) Most residential installs in 2026 use 540–575 Wp mono PERC / TOPCon panels.

System cost (₹ per kW) Turnkey installed cost before subsidy. Typically ₹50,000–65,000/kW.

How the sizing works

Each AC's average running draw = cooling capacity ÷ ISEER for its BEE star rating (an inverter AC cycling at part load draws far less than its nameplate watts). Daily consumption = that draw × your usage hours, plus your other monthly units ÷ 30. Required system size = daily kWh ÷ (your sun zone's peak sun hours × 0.80 performance ratio, which covers inverter losses, temperature derating and dust). As a rule of thumb, a 1.5-ton 5-star AC running 8 hours a day needs roughly 1.2 kW of panels. Treat this as a planning guide — a site survey by an empanelled vendor on the National Portal ↗ is the final word.

More solar tools on TheDiscomBill

Rooftop Solar Savings Calculator — cost, subsidy, monthly savings and payback for the system size above. · Solar Battery Backup Calculator — size a battery bank to run your AC through power cuts. · Electricity Cost Calculator — work out your monthly units appliance by appliance.