Rooftop solar remains one of the most reliable ways for a commercial or industrial consumer to cut power costs — but the rules governing how you are credited for the energy you export have changed materially. Understanding net metering, gross metering, and net billing is now essential to sizing your system correctly.
Net metering, gross metering, net billing — the difference matters
These three mechanisms determine the financial return of your rooftop system, and DISCOMs across states have been shifting between them:
- Net metering: you offset consumption against export and are billed only on the net. Most favourable for the consumer.
- Gross metering: all generation is exported at a fixed feed-in tariff and all consumption is billed separately. Returns depend entirely on the export rate.
- Net billing: a hybrid — self-consumption is valued at retail tariff, while export is credited at a (usually lower) rate.
Capacity caps and sanctioned load
Most DISCOMs limit rooftop capacity as a percentage of your sanctioned load or transformer capacity — commonly in the range of relevant local ceilings. For larger commercial and industrial consumers, this means your system size may be constrained not by your roof area but by your connection.
Key Takeaways
- Net metering is most favourable; many states are shifting to net billing or gross metering.
- Capacity is often capped relative to sanctioned load or transformer capacity.
- Billing treatment of exported units varies widely by state.
- Approval timelines and feasibility study requirements differ across DISCOMs.
- System sizing should be optimised for self-consumption, not just roof area.
The shift away from generous net metering
As rooftop adoption has grown, several DISCOMs have moved larger consumers from net metering toward net billing or gross metering — protecting their revenue but reducing the value of exported units. The practical consequence: systems should increasingly be sized to maximise self-consumption rather than to export surplus, because the surplus is worth less than it used to be.
Approval timelines and process
The typical rooftop approval path involves an application to the DISCOM, a feasibility/technical study, sanction, installation by an empanelled vendor, inspection, and meter installation. Timelines vary from a few weeks to several months depending on the state and system size. Larger systems usually trigger more detailed technical review.
How to approach it in 2026
- Confirm the metering regime your DISCOM applies to your consumer category and capacity.
- Check the capacity cap against your sanctioned load.
- Model returns based on realistic self-consumption, not nameplate generation.
- Factor the current export credit rate — do not assume full retail offset.
- Choose an empanelled EPC partner to avoid approval friction.
Rooftop solar still delivers strong returns for most commercial and industrial consumers. But in 2026 the design question has shifted from "how much can I export?" to "how much can I consume directly?" Getting that sizing right is the difference between a good investment and a great one.
