Solar Panel Wattages Available in India (2026)
| Panel Class | Wattage Range | Daily Output* | Typical Use |
|---|
| Small (12V) | 10 – 180 W | 0.04 – 0.7 units | Lights, fans, battery topping |
| Mid-size | 330 – 450 W | 1.3 – 1.7 units | Older residential installs |
| Standard residential | 540 – 575 W | 2.1 – 2.2 units | Most 2026 rooftop systems |
| High wattage | 600 – 620 W | 2.3 – 2.4 units | Space-constrained roofs |
*Per panel at 4.8 peak sun hours with a 0.8 performance ratio. Multiply by your panel count for array output,
or let the calculator above do it with your city's exact sun hours.
Watts, kW and kWh: Getting the Units Right
Watts (W) and kilowatts (kW) measure instantaneous power: what the panel can
deliver at full sun. kWh (units) measure energy over time: what your meter counts. A 550W
panel in a 4.8 sun-hour city produces about 550 × 4.8 × 0.8 ÷ 1000 = 2.1 units a day. When an installer quotes
"watts", always convert to daily units for your city before comparing against your consumption, which is
exactly what this solar watt calculator does.
Panel Watts, Array Watts and Inverter Watts Are Three Different Numbers
Most wattage confusion comes from mixing three figures. Panel watts (540 to 620W today) is
one module's lab rating. Array watts is panel watts × count: the number this calculator
converts to energy. Inverter watts caps instantaneous output and is deliberately set at or
slightly below array watts. When an installer says "a 5 kW system", ask which of the three they mean; a
"5 kW" quote with a 4 kW inverter and 9 panels is a very different product from 10 panels on a 5 kW
inverter. Enter array watts here, and use real daily consumption (from the
load calculator) when running "watts I need" mode.
Worked Example: 8 × 550W Panels in Bengaluru
Eight 550W panels make a 4.4 kW array. In Bengaluru's 4.8 sun hours that yields about
16.9 units a day and 507 a month: enough for a home using 450 to 500 units. Flip the mode:
a family targeting 12 units a day in the same city needs 12 ÷ (4.8 × 0.8) ≈ 3,150W, which the calculator
rounds to 3,150W and 6 panels of 550W. Both directions use the same physics; the mode just decides which side
of the equation you know.
Choosing a Panel Wattage When You Buy
- Space-rich roofs: buy on price per watt. Six 550W panels and five-and-a-bit 620W panels
make the same power; take whichever quote prices the watt cheaper with a solid warranty.
- Space-tight roofs: buy the biggest watt available. Each wattage step up extracts more
from the same footprint; verify the gain in the roof area
calculator.
- Match string voltages. All panels in a string should be the same model; mixing 540W and
620W drags every panel to the weaker spec.
- Check the tolerance line. Good modules list positive-only tolerance (for example
"+5W/-0W"), meaning you never receive below-rated glass.
Wattage Mistakes to Avoid
- Assuming watts scale with size linearly across brands-of-era. A physically larger old
400W panel can be less capable than a smaller modern 550W; compare watts and efficiency, not glass
dimensions.
- Confusing W with kWh. Watts are capability; kWh is delivery. A 550W panel delivers about
2.1 kWh a day, not 550 of anything.
- Ignoring the temperature coefficient. Two 550W panels can differ 3 to 4% in real Indian
heat if one loses 0.29%/°C and the other 0.40%/°C; the datasheet line matters more here than in Europe.
- Sizing "watts I need" from a winter day. Use annual average daily consumption, or summer
if you must err; a winter-sized array disappoints for half the year.
How This Wattage Calculator Works
Daily units = Total watts × Peak sun hours × 0.8 ÷ 1000
Watts needed = Target daily units × 1000 ÷ (Peak sun hours × 0.8)
Assumptions
- Performance ratio: 0.8, covering temperature, dust, wiring and inverter losses
- Sun hours: your selected city's stored average
- Rounding: wattage needed is rounded up to the next 50W step
