What Happens to Excess Solar Units You Generate in Chennai
Technical guide · 5 November 2026 · 6 min read
A common question after solar panel installation in Chennai is what happens to units the system produces but the house does not use. The answer depends on whether a net meter is installed and commissioned — and in Chennai, that means TANGEDCO has completed the meter swap.
How net metering works in Chennai
A grid-tied solar system in Chennai feeds your home first. If generation exceeds demand at any moment — say, the panels are producing 2 kW but only 0.8 kW is being used — the surplus 1.2 kW flows out through the net meter into the TANGEDCO grid. The net meter records both import (units drawn from the grid) and export (units pushed into the grid). At billing time, exported units are subtracted from imported units. You pay only on the net difference.
What appears on the EB bill
After net meter commissioning, the TANGEDCO bill shows two readings: import units and export units. If import exceeds export, you pay for the net import at the applicable slab rate. If export exceeds import in a billing period — which happens on long sunny months with low consumption — the surplus is carried forward as a credit to the next bill. TANGEDCO does not issue a cash payment for month-to-month surplus. The credit rolls over.
Annual settlement for excess export
If the annual export is still more than annual import after all carry-forward credits are applied, TANGEDCO in Tamil Nadu settles the remaining exported units at a feed-in tariff rate set by the Tamil Nadu Electricity Regulatory Commission (TNERC). That rate is typically lower than the retail import rate, which is why sizing your solar panel installation in Chennai to match your actual consumption is better than oversizing to export aggressively.
What happens before the net meter is installed
If a system is switched on before TANGEDCO commissions the net meter, surplus units may flow into the grid without being recorded. Some installers call this a "reverse metering" period — the old meter may actually run backwards. TANGEDCO does not formally sanction this, and it is one reason the meter application should be filed on the day of installation, not weeks later. For solar panel installation in Madipakkam, the sub-division office handling applications is the TANGEDCO office covering the Madipakkam–Medavakkam area.
How much export should you expect?
A 3 kW system in Chennai generates roughly 350–400 units per month in a good month (less in monsoon). A household using 250 units per month will export 100–150 units on a typical day. That export credit appears on the next bill. It does not disappear. How solar reduces the EB bill gives the actual bill maths with example numbers.