Metering rules determine how imported and exported solar electricity is measured and valued. Because regulations vary by state, consumer category, voltage and project size, every proposal should cite the current utility and regulatory route rather than promise a universal export benefit.
Key takeaways
- Net metering adjusts imported and exported energy in units.
- Net feed-in values imports and exports separately.
- Gross metering sells all generated energy under the approved arrangement.
- Rules and settlement periods must be confirmed with the DISCOM.
Net metering
Under a net-metering mechanism, eligible import and export units are adjusted according to the applicable billing rules. Treatment of surplus credits, settlement periods, banking and network charges depends on current regulation. The bi-directional meter records both directions of energy flow.
- Best understood as unit adjustment under defined rules.
- Eligibility may depend on category and capacity.
- Surplus treatment is not identical across states.
- Sanctioned load and interconnection limits still apply.
Net feed-in or net billing
In net feed-in, imported electricity is charged at the applicable retail tariff and exported electricity is credited at the approved feed-in value. The two monetary values are then settled according to the billing method. Export credit can be lower than the avoided cost of self-consumed energy, making daytime load matching important.
- Import and export values are calculated separately.
- Self-consumption can be more valuable than export.
- Network or other charges may apply.
- Use the latest official tariff order.
Gross metering
A gross-metered plant exports all approved generation to the utility under the specified commercial arrangement, while the consumer's load is billed separately. This is different from installing solar primarily for self-consumption. Connection, metering, evacuation and commercial conditions must be evaluated before investment.
- All plant generation is measured for export.
- Consumer import remains separately billed.
- Project economics depend on the approved tariff.
- Evacuation and metering costs may be material.
Tamil Nadu and India project checks
Tamil Nadu consumers should verify the current TNPDCL/TANGEDCO rooftop portal, TNERC orders and the applicable consumer-category process. Residential subsidy applications may also involve the national PM Surya Ghar portal. Commercial and industrial projects should obtain current regulatory and tax advice. Never rely on an old screenshot or tariff table.
- Confirm the current DISCOM application route.
- Check settlement period and credit rules.
- Verify network, meter and application charges.
- Record the applicable order in the proposal.
Frequently asked questions
Is exported solar credited at my retail tariff?
Not necessarily. It depends on the applicable metering method and current regulatory tariff.
Can every customer use net metering?
No. Eligibility varies by state, category, voltage, sanctioned load and capacity.
Where should Tamil Nadu consumers verify the rules?
Use the current TNPDCL/TANGEDCO rooftop portal and applicable TNERC orders, and confirm with the local office for the project.
Turn guidance into a practical system plan
Use Spectra’s engineering calculators for a preliminary estimate, then request technical verification before purchase or installation.