Reading Your Electricity Bill Before Solar: Units, Tariff Slabs and Sanctioned Load Explained
👤 SolarSahi Team 📅 April 2026 🔄 Regular updates ✓ DISCOM verified · April 2026
📄Key sectionSanctioned load
⚡What mattersUnits consumed
💰Tariff slabsPer unit rate
📊Check thisConnected load
🎯GoalRight size system
Why your electricity bill is the starting point for solar
Before you talk to any solar installer, before you check subsidy eligibility, and before you request a quote, you need to understand your electricity bill. It contains three numbers that determine the right solar system size for your home: your monthly units consumed, your sanctioned load, and your per-unit tariff rate. Getting these wrong means either an undersized system or wasted investment.
This guide walks through a standard North Indian electricity bill section by section. The layout varies slightly between DISCOMs, but the key fields are present in all of them.
The 5 numbers you need from your bill
⚡Monthly Units (kWh)Your total consumption last month. This is your most important sizing input.
💰Rate Per UnitWhat you pay per kWh in your tariff slab. Higher rate = faster solar payback.
🔌Sanctioned Load (kW)Your approved maximum load. Limits your solar system size in most states.
📅Billing Period1 month or 2 months. Affects how you calculate average monthly consumption.
🏷️Consumer CategoryResidential, commercial, agricultural. Must be residential for PM Surya Ghar subsidy.
How to calculate your average monthly consumption
A single month’s bill can mislead. Summer months show high consumption due to AC usage. Winter months show low consumption. For accurate solar sizing, collect the last 12 months of bills and calculate the average, or use the highest month as the design basis if you want full coverage.
1
Find the “Units Consumed” or “kWh” field on your billUsually labelled as “Present Reading minus Previous Reading” or simply “Units.” This is your gross consumption before any fixed charges.
2
Check if your billing is monthly or bimonthlySome DISCOMs bill every 2 months. If your bill shows 400 units for a 2-month period, your average monthly consumption is 200 units.
3
Add up 12 months and divide by 12This gives your true average monthly consumption. Use this number when discussing system size with any installer.
4
Note your peak month separatelyYour peak summer month tells you the maximum demand your solar system needs to address. Share both average and peak with the installer.
Sanctioned load and why it matters for solar sizing
Your sanctioned load is the maximum electrical load your DISCOM connection is approved for, measured in kilowatts (kW). In most Indian states, your solar system capacity cannot exceed your sanctioned load. A home with 3 kW sanctioned load cannot typically install a 5 kW solar system without first applying for a sanctioned load enhancement.
Sanctioned Load
Max Solar System
Typical Home Type
Action Needed
1 kW
1 kW
Studio or 1 room
May need enhancement for 2 kW+
2 kW
2 kW
1-2 BHK basic
Upgrade first for 3 kW system
3 kW
3 kW
2-3 BHK standard
No change needed for standard system
5 kW
5 kW
3-4 BHK with heavy AC
Can install up to 5 kW directly
10 kW+
Up to sanctioned load
Large home or villa
Full flexibility on sizing
💡
If your sanctioned load is lower than your desired solar system size, apply for sanctioned load enhancement at your DISCOM consumer section before starting the PM Surya Ghar application. This adds 30 to 45 days but avoids rejection later.
DISCOM field guidance · April 2026
Understanding tariff slabs and why they matter
Most Indian DISCOMs use a slab-based tariff. The first 100 units cost less per unit than units 101 to 200, which cost less than units beyond 200. The higher your consumption, the higher the effective rate you pay. This is exactly why high-consumption homes get the best solar payback , solar replaces the most expensive units first.
0-100
Slab 1 · Lowest rate
Rs 3-4 per unit
101-200
Slab 2 · Medium rate
Rs 5-6 per unit
200+
Slab 3 · Highest rate
Rs 7-9 per unitSOLAR SAVES MOST HERE
Frequently asked questions
Where do I find my consumer number on the bill?
Your consumer number is printed at the top of the bill, usually in a prominent box. It may be labelled “Consumer No.”, “Account No.”, or “Service No.” depending on your DISCOM. This exact number is what you enter on the PM Surya Ghar portal. Copy it carefully as one wrong digit fails the portal verification.
What if my bills are very different month to month?
This is normal for homes with seasonal AC usage. Use a 12-month average for system sizing. If you want your solar system to cover even peak summer months, use the highest-consumption month as your design target. Share both numbers with your installer and ask for a recommendation.
My sanctioned load is only 2 kW but I want a 3 kW solar system. What do I do?
Apply for sanctioned load enhancement at your DISCOM before starting the PM Surya Ghar application. The process involves submitting a request at the consumer section with your property documents and paying a nominal enhancement fee. Processing takes 30 to 45 days in most states. Once enhanced, proceed with the solar application.
Does my consumer category affect solar eligibility?
Yes. The PM Surya Ghar subsidy is only for residential consumer categories. If your connection is under a commercial, industrial, or agricultural tariff, you do not qualify for the residential subsidy. Some homeowners have mixed-use properties where the electricity connection is under a commercial category , these are not eligible.
How do I get old bills if I have lost them?
Login to your DISCOM portal or mobile app and download the last 12 months of bills as PDFs. Most DISCOMs including BSES, UPPCL, JVVNL, and DHBVN provide this under the “Bill History” or “Previous Bills” section. Alternatively, visit your DISCOM consumer centre with your consumer number.
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