DISCOM Regulations & Billing

Solar Net Metering Billing Explained: Energy Banking, Settlement Cycles & TOD Tariff in India (2026)

✍️ By Deepak Chopade • 📅 2026-10-06 • ⏱️ 10 min read

  💡 Demystifying Your Solar Net Metering Bill: After installing rooftop solar, many consumers find their first DISCOM electricity bill confusing. Bi-directional smart meters record electricity flowing in two directions: Import (kWh drawn from the grid at night) and Export (surplus solar kWh injected into the grid during daytime). Understanding how net units, energy banking credits, Time-of-Day (TOD) tariff slots, and fixed connection charges are calculated ensures you never overpay your electricity distribution company.

1. Anatomy of a Bi-Directional Smart Solar Meter Display

Your bi-directional net meter continuously cycles through digital display parameters:

Meter Display Code	Parameter Name	What It Means
KWH (I / Imp)	Import Active Energy	Total grid electricity consumed when solar is not generating (Night / High load)
KWH (E / Exp)	Export Active Energy	Total surplus solar electricity sent back to the DISCOM grid during daytime
KWH (Net)	Net Energy (Imp - Exp)	If Import > Export: You pay for Net Units. If Export > Import: Surplus units are banked.
MD (kW / kVA)	Maximum Demand	Highest 15-minute peak power drawn from the grid during the monthly cycle

2. Step-by-Step Net Metering Calculation Formula

Here is how your monthly DISCOM bill is computed:

$$ ext{Billed Energy Units} = ( ext{Current Import} - ext{Previous Import}) - ( ext{Current Export} - ext{Previous Export}) - ext{Banked Units}$$

Example: If you imported 450 units from grid and exported 600 units of solar generation, your Net Consumption is -150 units. Your energy charge for the month is ₹0, and 150 units are added to your energy bank balance for subsequent months.

3. Time-of-Day (TOD) Solar Energy Banking Rules

Most Indian states (Maharashtra, Gujarat, Karnataka, Haryana, Punjab, Tamil Nadu) implement Time-of-Day (TOD) tariffs for commercial, industrial, and high-consumption residential consumers:

Solar Hours (09:00 - 18:00): Normal baseline tariff rates. 100% of solar generation occurs in this window.
Peak Evening Hours (18:00 - 22:00): High tariff surcharge (typically +20% to +25%). Energy banked during solar hours is adjusted against peak hours with a conversion ratio specified by state regulatory commissions (SERC).
Night Off-Peak Hours (22:00 - 06:00): Discounted tariff rebate (typically -15% to -20%).

4. Annual Settlement Cycle & Surplus Encashment (March 31)

Energy banking does not accumulate infinitely. Under standard State Electricity Regulatory Commission (SERC) regulations:

Settlement Period: Runs from April 1 to March 31 each financial year.
Surplus Unit Payout: Unadjusted surplus units remaining in your energy bank as of March 31 are purchased by the DISCOM at the Average Power Purchase Cost (APPC) rate (typically ₹2.50 to ₹3.80 per unit) and credited to your April bill.

5. 4 Common DISCOM Net Metering Billing Errors to Check

Missing Solar Export Deduction: Verify that the meter reader recorded both Import and Export registers on the bill, not just Import.
Fixed Demand Charges Billed on Full Solar Capacity: Fixed charges must be billed strictly on your sanctioned contract demand (kW/kVA), never on your connected solar plant capacity.
Non-Adjustment of Carried Forward Banked Units: Always check the "Cumulative Banked Units" column on page 2 of your bill to verify past surplus balances.

6. Frequently Asked Questions (FAQs)

Q1: Can my electricity bill become exactly ₹0 after installing solar?

Your energy charge component can become ₹0. However, standard statutory fixed charges, meter rent, and electricity duty on net consumption are still payable as per DISCOM tariffs.

Q2: What happens if my solar export is higher than import every month?

Surplus energy credits roll over month after month and are settled in cash/bill credit at the end of the annual settlement cycle on March 31st.