A tea packaging unit owner near Jorhat once told me his electrician had convinced him running machinery at midnight would save the most money, based on some general advice about “off-peak discounts.” When we actually checked APDCL’s industrial tariff structure, there’s no midnight discount at all, the actual rebate window is 9 AM to 5 PM, the solar hours. He’d been running a partial night shift for months chasing a discount that didn’t exist for his category. That kind of mix-up is common because industrial tariff structures genuinely are more layered than domestic ones. Here’s how it actually works, category by category, and a calculator to check your own numbers.
APDCL industrial tariff categories
Industrial connections in Assam split by connected load or contract demand, and the category boundaries matter more than most people expect.
| Category | Load / Demand Band | Energy Charge | Fixed Charge |
|---|---|---|---|
| LT Small Industry (Rural) | Up to 30 kW | ₹6.84/kWh | ₹70/kW/month |
| LT Small Industry (Urban) | Up to 30 kW | ₹7.09/kWh | ₹80/kW/month |
| HT Small Industries | 30 kW (35 kVA) to 50 kVA | ₹7.29/kWh | ₹90/kVA/month |
| HT-I Industries | 50 kVA to 150 kVA | ₹7.69/kWh | ₹200/kVA/month |
| HT-II Industries | Above 150 kVA | ₹8.09/kWh (Option 1) or ₹7.69/kWh (Option 2) | ₹280/kVA or ₹360/kVA |
There’s no separate “Medium Industry” slab between LT Small and HT categories, the moment your load crosses 30 kW (35 kVA), you move straight into HT billing, which changes both your rate and how demand charges work.
The Time of Day structure, correctly
This is the part that trips people up most, including that tea packaging unit owner. The actual TOD windows are:
- 10 PM to 9 AM: Normal Energy Charges
- 9 AM to 5 PM (solar hours): 80% of Normal, a 20% rebate
- 5 PM to 10 PM (peak hours): 120% of Normal, a 20% surcharge
There’s no separate midnight-to-dawn discount, the rebate window is specifically during the day, when solar generation is highest on the grid, not at night. HT-II Industries consumers on Option 2 don’t get any TOD adjustment at all, whichever hours they run in.
How the calculation works
- Base Energy Charges = Total Units (kWh) × Category Rate
- TOD Adjustment = apply the 20% rebate to solar-hour units and 20% surcharge to peak-hour units, on top of the base charge already applied
- Fixed Demand Charges = Contract Demand (kVA) × Category’s Fixed Rate
- Electricity Duty = 5% of Base Energy Charges
Now a smaller rural unit on LT Small Industry:
The tea packaging unit was closer to the first example, once we corrected the shift timing to actually land in the solar-hour window, the bill dropped more than the midnight shift ever managed to.
How to Use the Calculator
Step 1. Select your category: LT Small Industry (Rural/Urban), HT Small Industries, HT-I, or HT-II.
Step 2. Enter your total monthly consumption in units (kWh/kVAh). Step 3. Enter your Contract Demand/Connected Load and the share of units consumed during peak hours (5 PM to 10 PM) and solar hours (9 AM to 5 PM).
Step 4. Click “Calculate Industrial Bill” to see Base Energy Charges, TOD adjustments, Fixed Demand Charges, Electricity Duty, and your total.
Some things people ask us often
Industrial bills me kVAh billing kya hoti hai aur Power Factor (PF) isko kaise affect karta hai?
kVAh billing me active power (kWh) aur reactive power dono account hoti hain. Power Factor 1.0 (unity) ke paas rehne par kVAh aur kWh lagbhag barabar rehte hain. Low Power Factor hone par kVAh units badh jati hain, chahe actual kaam ke liye utni hi energy use ho rahi ho, aur isse bill mehnga ho jata hai.
Assam me factories bijli ka bill kaise kam kar sakti hain?
Teen practical tarike: pehla, heavy machinery ko solar hours (9 AM se 5 PM) me shift karein, midnight nahi, taaki actual 20% rebate mile. Doosra, Automatic Power Factor Correction (APFC) panel install karke Power Factor 0.98 se upar maintain karein, jisse kVAh billing kam ho. Teesra, rooftop solar net metering lagakar grid-exported units par credit praapt karein.
Sanctioned Demand se zyada load lene par kya penalty hoti hai?
Agar actual maximum demand (MD), sanctioned Contract Demand se exceed kar jaye, APDCL fixed charge ko us excess portion par teen guna normal rate se levy karti hai, sirf double nahi.
Hamari unit 30 kVA ke aas paas fluctuate karti hai, kabhi 29 kabhi 31, kya ye LT ya HT dono categories ke beech switch hoti rehti hai, ya ek baar decide hone ke baad fixed rehta hai?
Category aapke Contracted Demand (jo agreement me fix hota hai) se decide hoti hai, actual daily fluctuation se nahi. Agar aapka contract 30 kVA ya usse kam par set hai, aap LT Small Industry me hi rahenge, chahe kisi din actual draw thoda zyada ho jaye, jab tak wo Overdrawal Penalty ka trigger na bane. Category badalne ke liye aapko formally apna Contract Demand revise karwana padta hai.
Is this an official APDCL calculator?
No. This tool applies the published industrial tariff schedule to estimate your bill closely. These are the rates approved for the prevailing tariff order, which APDCL has proposed to continue unchanged into FY 2026-27, pending final confirmation, your actual bill is generated by APDCL directly based on your metered demand and consumption.
Official Resources
Industrial tariff categories and TOD rules do get revised through AERC orders, so it’s worth checking directly:
If your unit is shifting production hours to chase a TOD discount, it’s worth confirming the exact window on your current bill first, the difference between a real rebate hour and an assumed one is exactly what cost that tea packaging unit months of a pointless night shift.
