# Will my grid-connected rooftop solar keep running during a power cut?

Canonical: https://senseible.earth/answers/rooftop-solar-during-power-cut-islanding

No, not a standard grid-connected plant. The Ministry of New and Renewable Energy (MNRE) specification requires inverters attached to the grid to turn off in a short period when the grid fails, and the plant must have islanding protection. A plant that keeps running in an outage needs a different design.

## What the specification says

These are clauses from the technical specification in Annexure 3 of MNRE's guidelines for its residential rooftop solar scheme, Pradhan Mantri Surya Ghar: Muft Bijli Yojana. A factory is not bound by them, but they are a published checklist to hold a quotation against.

- Clause 2.11: in the event of a power failure on the electric grid, it is required that any independent power-producing inverters attached to the grid turn off in a short period of time.
- This prevents the inverters from continuing to feed power into small sections of the grid, known as islands. Powered islands present a risk to workers who may expect the area to be unpowered, and they may also damage grid-tied equipment.
- The rooftop system shall be equipped with islanding protection. Disconnection due to under and over voltage conditions shall also be provided, if not available in the inverter.
- The standards table names IEC 62116:2014 or IS 16169 as the test procedure of islanding prevention measures (International Electrotechnical Commission, IEC; Indian Standard, IS).
- Annexure 4 clause 2.2: the consumer installs an isolation device, both automatic and built in to the inverter and an external manual relay, and the distribution licensee shall have access to it.

## What that means on your shop floor

For a grid-tied plant, at noon on a day the grid trips, the roof may be making power but the inverter switches off and your lines go dark, so the diesel generator starts if you have one. My reading: solar by itself does not cut your generator hours in an outage, though it cuts the units you buy on the days the grid is up. To ride through a cut you need a design with a battery or a hybrid arrangement. The scheme text lists battery hybrid systems among the non-export types, but the choice of equipment and the approval route are for your designer and your state regulator.

## Questions to put to the vendor

- Does the quoted inverter keep supplying the factory when the grid fails? If it is grid-tied only, the answer should be no.
- If you want backup, which loads, for how many hours, and what battery size does that need.
- How the plant restarts after the grid returns. The specification asks for automatic wake-up, synchronization and shutdown.
- Whether the generator and solar can share one incomer without back-feeding. Ask for a drawing.

## What an outage costs a grid-tied plant (example numbers)

- Plant output at noon: 60 kilowatts
- A 3 hour cut: 60 x 3 = 180 kilowatt hours (kWh) not made, because the inverter is off
- The factory runs on the diesel generator for those 3 hours instead

Output and duration are example numbers. Diesel burnt in the generator is Scope 1.

## What Senseible does here

Senseible reads electricity bills into monthly records, so the units you import month by month sit in one place. It does not size batteries or backup systems.

- [Do rules require solar and batteries instead of diesel backup](https://senseible.earth/answers/dg-set-replace-with-solar-battery-rule)
- [Battery backup or diesel set: emissions](https://senseible.earth/answers/battery-backup-vs-dg-set-emissions)
- [Does battery storage reduce Scope 2](https://senseible.earth/answers/does-battery-storage-reduce-scope-2-emissions)
- [Grid failure and lost solar export](https://senseible.earth/answers/grid-failure-and-lost-solar-export-who-pays)

Sources: [Ministry of New and Renewable Energy (MNRE), Guidelines for PM-Surya Ghar: Muft Bijli Yojana, Central Financial Assistance to Residential Consumers, with Annexures 2 to 4](https://mnre.gov.in/static/uploads/2025/08/f20f6d61628866e66b612810b49abd78.pdf)

Last reviewed 2026-11-06. Re-check clause numbers and figures against the current version of the guidelines before you rely on them. Clauses are in Annexure 3, section 2, and Annexure 4. Your state rules decide how a backup-capable plant is approved.