Net Metering After Solar Panel Installation in Chennai: What the EB Bill Shows

After solar panel installation in Chennai, one of the first disappointments is the EB bill arriving without any visible change. Usually the reason is simple: the net meter has not been commissioned yet. Once it is, the bill changes in a specific way that takes a cycle or two to understand.

The net meter replaces the old import-only meter

TANGEDCO swaps the existing single-direction meter for a bidirectional net meter after the application is processed. This new meter has two registers: one for units imported from the grid (what you consume that solar does not cover), and one for units exported to the grid (surplus solar generation). The meter itself records both directions; your bill is calculated on the difference.

What the bill looks like in the first net-metered cycle

In the first full billing cycle with a working net meter, you will see two consumption figures. Some TANGEDCO bills label them as 'Import' and 'Export' or 'Generation'. The net consumption is import minus export. You are billed on that net figure at the applicable residential slab rate. If you imported 180 units and exported 90, you pay for 90 net units.

Why the first bill may still seem high

If the net meter was installed part-way through a billing cycle, the bill covers both the pre-meter period (full import billing) and the post-meter period (net billing) in the same statement. It looks high because it is two different calculations. The second cycle shows the full benefit. This is not an error — it is how TANGEDCO handles mid-cycle meter changes.

When the bill becomes very low or zero

A correctly sized system in Chennai can bring the consumption portion of the bill to near zero in peak generation months (February to May and October). The fixed charges — meter rent, demand charge, and applicable taxes — remain. These are not avoidable with solar; they are part of having an EB connection. A very low bill does not mean the solar is not working; it means the system is working as designed.

How the bill behaves in monsoon

During Chennai's northeast monsoon (October to December), generation drops on overcast days. Import increases relative to other months. The bill rises slightly compared to summer. This is expected and does not indicate a problem with the installation. Heavy rain and solar generation covers the specific numbers. For solar panel installation in Chennai, year-round generation data from ZeroEB projects shows an annual average that absorbs the monsoon months.

What to do if the bill is not changing

If three bills have passed since installation and the figures look identical to before solar, check: (1) has TANGEDCO confirmed the net meter is commissioned, (2) is the inverter display showing daily generation above zero, (3) is the generation monitor app showing data. If the inverter is running but the bill is unchanged, the meter may still be the old single-direction type. Contact your installer to follow up with the TANGEDCO sub-division.