Net metering is the mechanism that makes rooftop solar financially worthwhile for most homes: instead of storing the extra power your panels generate, you send it back to the grid and get credited for it. But most homeowners never see how the calculation actually works — only the bill at the end.
This guide breaks down what a bi-directional meter measures, how bill credits get calculated, and what happens to credits you don't use.
What Net Metering Actually Measures
A net meter tracks electricity flowing in both directions — power you pull from the grid, and power your panels push back into it. Your bill is based on the difference between the two, not on either number alone.
- •Import: units you draw from the grid when your panels aren't producing enough (nighttime, cloudy days).
- •Export: units your system sends back to the grid when it produces more than your home is using.
- •Net units: import minus export — this is the number your bill actually charges you for.
Gross vs Net Metering
A handful of states use gross metering instead, where every unit you generate is bought at a fixed rate and every unit you consume is billed separately — the two never offset each other. Under PM Surya Ghar, net metering is the default for residential rooftop systems in almost every state.
How Bill Credits Are Calculated
Each billing cycle follows the same basic sequence:
- 1.The DISCOM reads your net meter at the end of the billing period.
- 2.It compares total units imported against total units exported for that period.
- 3.If you imported more than you exported, you're billed for the difference at your normal tariff.
- 4.If you exported more than you imported, the surplus becomes a credit — either carried forward or settled at a separate export tariff, depending on your state's regulations.
What Happens to Unused Credits?
This is where most confusion comes from, because the rule isn't the same everywhere:
- •Some states roll unused credits forward indefinitely, month to month.
- •Others settle or reset the credit balance annually, at the end of the financial year.
- •A few pay out surplus export units in cash at a fixed feed-in tariff instead of carrying a credit at all.
Check your specific DISCOM's net metering regulations before assuming your credits behave like a rollover data plan — in several states, they don't.
How ZEP360 Tracks Net Metering for Every Site
For an EPC managing hundreds of installed systems, tracking each customer's net metering status by hand doesn't scale. ZEP360 logs every site's commissioning date, DISCOM, and meter status in one place, so support teams can answer a customer's billing question without digging through paperwork from a job that closed a year ago.
Frequently Asked Questions
Who pays for the bi-directional meter?
In most states the DISCOM installs and owns the net meter, and the cost is bundled into your installation or billed separately at a fixed rate — it varies by state, so confirm this with your DISCOM before installation.
Can I oversize my system to generate more credits?
Most DISCOMs cap net metering approval at your sanctioned electricity load, so you can't arbitrarily oversize a system purely to generate export credits.
Can I transfer my credits if I move houses?
No. Net metering credits are tied to the electricity connection and meter, not to you personally — they don't transfer to a new address.
