Electricity is one of the biggest operating costs for factories in Tamil Nadu. Whether you're on TANGEDCO's LT-3, HT-1, or HT-2 tariff slab, this free solar savings calculator shows you exactly how much your factory can save by switching to solar — under a PPA, captive, or group captive model. Enter your monthly EB bill, select your tariff slab and roof area, and get your estimated monthly savings, payback period, and 25-year cumulative returns instantly. Used by industrial buyers across Chennai, Coimbatore, Tirupur, and Salem.
Solar Savings Calculator
Enter your monthly TANGEDCO bill to calculate savings
Estimates based on TANGEDCO 2026 tariffs & Tamil Nadu solar irradiance (1,400 kWh/kW/year). Actual savings vary by site. Get a free detailed assessment →
How the calculator works
This industrial solar ROI calculator uses four inputs to generate your savings estimate: your monthly TANGEDCO electricity bill, your applicable tariff slab (LT-3, HT-1, or HT-2), your available rooftop or ground area in square feet, and your preferred solar deployment model.
From these, it calculates your recommended system size in kW, the annual units of electricity your plant would generate (based on Tamil Nadu's average irradiance of 1,400 kWh/kW/year), your estimated monthly saving in rupees, and both the payback period and 25-year cumulative return.
Your monthly TANGEDCO bill in rupees. This determines your consumption volume and savings baseline.
LT-3, HT-1, or HT-2. Higher slabs mean faster ROI because the solar cost gap is wider.
Available rooftop or land area caps your maximum system size. Every 100 sq ft supports ~1 kW.
PPA requires zero investment. Captive delivers lower per-unit cost. Group captive suits mid-size loads.
What affects your solar savings in Tamil Nadu?
Several factors determine how much a Tamil Nadu factory saves by going solar. Understanding them helps you choose the right structure and set realistic ROI expectations.
The higher your per-unit grid cost, the wider the gap solar can capture. HT-2 factories at ₹10/unit save significantly more per kWh than LT-3 consumers at ₹7.50/unit.
LT-3: ₹7.50
HT-1: ₹8.50
HT-2: ₹10.00
PPA and BOOT models cost ₹3.10–3.30/unit with zero capital outlay — savings from day one. Captive ownership drops your cost to ₹2.40–2.60/unit after the 3–5 year payback, delivering higher long-term returns.
Your available rooftop or land constrains system size. A 10,000 sq ft roof typically supports 80–100 kW — enough to offset 30–40% of a mid-size factory's consumption.
Adding battery storage lets your factory use stored solar power during peak evening hours, cutting demand charges and further reducing grid dependency beyond what rooftop solar alone can achieve.
Tamil Nadu receives among India's highest solar irradiance — 1,350 to 1,500 kWh/kW/year depending on location. Tirupur and Madurai zones outperform Chennai slightly.
Factories above 1 MW sanctioned load qualify for open access tariffs, enabling group captive and third-party PPA structures with even lower per-unit costs and more flexibility.
Frequently Asked Questions
Common questions from Tamil Nadu industrial buyers about solar savings, payback, and TANGEDCO tariffs.
Get a free, site-specific solar assessment from NST Solar's engineering team — including actual TANGEDCO consumption analysis, system sizing, and financial model.