Solar Net Metering & Banking Settlement Calculator (DISCOM Unit Credits, Sizing & March 31 True-Up)
Estimate your monthly electricity bill offset, surplus units banked on your bidirectional meter, and year-end cash payout at APPC rates across state utilities in India.
1. State & DISCOM Policy
1:1 Net MeteringMERC Rules: Surplus solar units banked month-to-month. Net settled at ₹2.50/unit at FY true-up (March 31).
2. System Capacity & Household Consumption
3. Tariff Rates & DISCOM Charges
Weighted average slab rate including energy charges & duty.
Rate paid for leftover banked units at annual settlement (March 31).
Estimated Power Bill with Solar
+42 Units / month Surplus Banked
₹1,260 Cash Payout from DISCOM
Monthly Energy Flow & Allocation
Visual mapping of generated solar power vs household draw
12-Month Financial Year Seasonal Simulator
Simulates real solar irradiance, monsoon dips & March 31 true-up
| Month | Solar Gen | House Draw | Exported | Banked Units | Bill Paid (₹) |
|---|---|---|---|---|---|
How Solar Net Metering, Energy Banking & Annual True-Up Settlements Function in India
In India, residential and commercial rooftop solar systems operate under regulatory codes formulated by State Electricity Regulatory Commissions (SERCs). While solar panels generate maximum power during the middle of the day (10:00 AM to 3:00 PM), household power consumption frequently peaks during the morning and evening hours.
A bidirectional net meter resolves this supply-demand mismatch by treating the local electricity distribution grid (DISCOM) as a virtual storage battery. Instead of requiring expensive on-site chemical battery storage, excess solar power is exported into the utility grid during sunny hours, accumulating credit units that offset power consumed during the night.
The Three Solar Metering Models: Net Metering vs Net Billing vs Gross Metering
Unit-for-Unit Offset
Every 1 unit of solar electricity exported cancels out 1 unit of grid consumption on your monthly bill. You save at your highest domestic slab tariff (₹6.00 to ₹16.00/unit). Surplus units are carried forward in an energy bank until the annual true-up.
Adopted in: Maharashtra, Delhi, Gujarat, Karnataka, UP.
Dual Tariff Valuation
Energy imported is billed at full commercial/residential retail slab rates, while energy exported to the grid is credited in rupees at a much lower wholesale pooled tariff (typically ₹2.25 to ₹2.75/unit). Reduces consumer payback efficiency.
Adopted in: Tamil Nadu (TNERC), commercial C&I systems.
Complete Power Export
All electricity generated by your rooftop solar plant is fed directly to the DISCOM through a dedicated export meter at a fixed PPA feed-in tariff. The homeowner purchases 100% of their consumption from the grid under standard retail tariff slabs.
Used for: Large ground-mount or institutional arrays.
State DISCOM Solar Net Metering & True-Up Regulations Matrix (2025–2026)
| State / Regulatory Commission | Eligible Capacity Limit | Banking Settlement Window | Surplus Unit True-Up Rate | Special State Incentive |
|---|---|---|---|---|
| Maharashtra (MERC / MSEDCL) | Up to 100% Sanctioned Load (Max 1 MW) | Annual (April 1 to March 31) | ₹2.50 / unit (MERC Generic Tariff) | TOD Banking permissible for LT residential |
| Delhi (DERC / BSES, TPDDL) | 100% Sanctioned Load (Single/3-Phase) | Annual (April 1 to March 31) | ₹3.11 – ₹3.40 / unit (APPC rate) | +₹3.00/kWh Delhi GBI Incentive (up to 3kW) |
| Gujarat (GERC / Surya Gujarat) | 100% Sanctioned Load | Monthly billing cycle true-up | ₹2.25 / unit (GERC Discovered Tariff) | Immediate monthly adjustment on power bill |
| Karnataka (KERC / BESCOM) | Up to Sanctioned Load (LT consumers) | Annual true-up (Financial Year end) | ₹3.82 – ₹4.02 / unit | Gruha Jyothi compatibility on balance draw |
| Tamil Nadu (TNERC / TANGEDCO) | Up to 100% of Sanctioned Load | Bi-monthly billing cycle (Net Feed-In) | ₹2.28 / unit (75% of pooled cost) | Currency credit rather than 1:1 unit banking |
| Uttar Pradesh (UPERC / UPPCL) | Up to Sanctioned Load | Annual (April 1 to March 31) | ₹2.50 / unit (APPC) | +₹30,000 UPNEDA State Subsidy Top-up |
The Sizing Pitfall: Why You Should Not Blindly Oversize
A common trap is installing a 10 kW plant when your household only consumes 400 units/month. While you will easily eliminate your power bill, your surplus units (e.g. 800 units/month) will be sold to your DISCOM at the wholesale APPC rate (₹2.25 to ₹2.50/unit) at March 31 true-up.
Paying ₹45,000 to ₹55,000 per extra kW of capital expenditure to generate electricity that sells for only ₹2.50/unit yields a poor payback period of 8 to 11 years. In contrast, sizing your system to offset high-slab retail units (worth ₹8 to ₹16/unit) pays for itself in just 2.0 to 3.2 years under the PM Surya Ghar subsidy!
5 Steps to Get Your Bidirectional Net Meter Installed with Your DISCOM
National Portal Registration
Register on `pmsuryaghar.gov.in` with your consumer number, DISCOM name, and mobile number.
Feasibility Approval
DISCOM examines local distribution transformer (DT) capacity (max 80% solar loading allowed) and grants technical NOC.
Installation by Vendor
An MNRE-empanelled solar installer erects ALMM/DCR solar panels and a grid-tied inverter complying with IEEE 1547 standards.
Joint Meter Inspection
DISCOM junior engineer inspects earthing, lightning arrestor, and tests meter dual registers (Import/Export kWh).
Net Meter Commissioning
Old unidirectional meter is swapped for a bidirectional smart meter. Online commissioning certificate triggers DBT subsidy release.
Frequently Asked Questions (Solar Net Metering & Banking)
What is a bidirectional net meter and how does it differ from a regular meter?
A standard consumer meter only counts energy in one direction (Import). If you export solar power through an old mechanical or electronic meter, it may either fail to record it or erroneously add it to your consumption bill. A bidirectional meter has two distinct electronic registers: Register 1 records energy imported from the grid, and Register 2 records solar surplus exported into the grid.
Do I still get an electricity bill if I have rooftop solar?
Yes, your DISCOM continues generating a monthly invoice. If your solar export matches or exceeds consumption, energy charges become ₹0. However, the bill will reflect mandatory fixed charges (based on your sanctioned load in kW), meter rent, and applicable municipal cess or GST.
When does the DISCOM pay for excess banked units?
Most state utilities (like MSEDCL, BSES, UPPCL, and BESCOM) carry forward banked energy month-to-month until March 31st (end of financial year). Any unadjusted surplus units remaining on March 31 are settled at the SERC-mandated APPC rate either as an advance credit on your April bill or through direct bank deposit (NEFT).
What is the transformer capacity limit for net metering in India?
Under Central Electricity Authority (CEA) regulations, the total cumulative capacity of all rooftop solar systems connected to a distribution transformer (DT) is typically capped between 70% and 80% of the transformer's rated kVA capacity. If your local DT is already at maximum capacity, the DISCOM may reject or delay net meter approvals until the DT is upgraded.
Can I install rooftop solar if I live in an apartment or housing society?
Yes. Residential Welfare Associations (RWAs) and apartment complexes can install rooftop solar under the PM Surya Ghar group housing scheme for common area lighting, lifts, water pumps, and EV chargers. In some states, Virtual Net Metering (VNM) allows solar generation from a shared terrace to be proportionately allocated across individual resident flat meters.
Ready to Install? Claim Up to ₹78,000 Direct Bank Subsidy.
Calculate your exact capital cost, government financial assistance, rooftop area required, and 7.0% concessional SBI loan EMI on our official PM Surya Ghar Solar Subsidy Calculator.