On-grid solar sizing
Calculate from either monthly kWh or Electricity Board sanctioned load. All estimated values require site and engineering verification.
Calculate using
Select one input method. The unselected value will not affect the calculation.
TN domestic energy charge
LT domestic; monthly equivalent of the bimonthly slab/subsidy schedule
- Utility / regulator
- TNPDCL / TNERC
- Tariff validity
- FY 2026–27; current subsidy orders
Order No. 5 of 2026 provides a total 200 free units per bimonthly cycle for eligible domestic consumption up to 500 units. Final TNPDCL billing remains bimonthly.
Open official tariff source ↗Detailed load & calculation breakdown
Review the entered load data and each calculation step used to produce the recommendation above.
Load / input data
How the result is calculated
- 01
Selected sizing method = monthly electricity consumption: 450 kWh/month. Sanctioned load is not used in this method.
- 02
Daily energy demand = 450 kWh ÷ 30 = 15.00 kWh/day.
- 03
Raw array = 450 ÷ (30 × 4.60 state yield hours × 0.80 performance ratio) = 4.08 kW; practical target = 4.5 kW.
- 04
Module count = 4500 W ÷ 550 Wp = 9 panels; installed DC capacity = 4.95 kWp.
- 05
Expected generation = 4.95 × 4.60 × 30 × 0.80 = 546.5 kWh/month.
- 06
Energy-charge saving = charge before solar minus charge on residual units = ₹2910 − ₹0 = ₹2910/month.
Formula, assumptions & engineering checks
Formula: System kW = monthly kWh ÷ (30 × state solar-yield hours × performance ratio), rounded up to a practical module configuration.
Assumptions: Consumption-based sizing uses 4.6 peak-sun-hours/day, 80% performance ratio and 550 Wp modules for Tamil Nadu. Sanctioned load is not used in this mode and must be verified separately before the DISCOM application. Energy savings use only verified energy-charge slabs and exclude fixed/demand charges, duty, FAC/FPPCA, ToD, power-factor charges, taxes and export-settlement differences.
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Preliminary estimate only. Final equipment and cable selection must be verified by a qualified engineer using the latest applicable IEC, IS, BIS, CEA, utility and manufacturer requirements.