CEIG Approval for a 1 MW Solar Plant: Drawings, Tests and the Inspection

A 1 MW solar plant almost always needs the state Electrical Inspector's approval before it is energised, because each state notifies the capacity above which a generating unit, renewable ones included, must be inspected, and 1 MW sits above every threshold we could read. You file drawings first, build to them, record the tests, and the inspector checks the plant and grants safety approval. Which officer decides, and on what capacity, varies by state.

When does a 1 MW plant need CEIG approval?

Regulation 34 of the CEA safety regulations 2023 leaves the capacity above which a generating unit must be inspected before commissioning to the state government's notification. Regulation 45 then says that every installation above the notified voltage, and the apparatus of generating units above that capacity, is inspected and tested by the Electrical Inspector before supply starts, and that the supplier may not commence supply until the Inspector's written approval is obtained. A 1 MW plant also brings an HT interconnection and usually a step-up transformer, so you are approving an electrical installation, not only a solar array.

One trap is the unit of capacity. A plant sold as "1 MW" may be 1,000 kW of inverter capacity with more DC capacity on the roof. Karnataka's March 2025 delegation notice counts rooftop solar in kWp, and its boundary sits exactly at 1,000 kWp, so the officer who decides could change with how the office counts. Ask which figure the office uses, and put that figure on the drawings.

How do the states differ?

What goes into the drawing set?

Expect the single-line diagram to run from the modules through string combiners and inverters to the LT panel, step-up transformer, HT breaker or RMU and the DISCOM's metering point, with ratings, protection and the net-metering arrangement shown. Add an equipment layout with clearances, an earthing layout with the standard earth pit, the PV capacity and inverter calculation, and, where your state asks for it, the nodal agency's sanction letter. Karnataka's rooftop procedure also asks for the supply company's no-objection letter and, if the owner claims central subsidy, the nodal agency's no-objection.

Three details from the regulations should be visible on the drawings. For a transformer of 1,000 kVA and above, regulation 37 requires a circuit breaker on the primary side. At the same rating, regulation 47 requires a Buchholz relay, a pressure relief device and winding and oil temperature protection with alarm and trip contacts. And where two supplies are not meant to run in parallel, such as grid and DG, breakers must be interlocked against back-feed. Regulation 121(4) also asks for a fire detection and automatic suppression system as per relevant standards; our note on DC fire safety on rooftops covers what that means on a roof. State what is in the contractor's licence file as well: the licensed electrical contractor and supervisor have to be named and endorsed.

Which tests must be on record before inspection day?

Regulation 45(5) makes the owner test every circuit of an installation above the notified voltage before applying, record the results and submit them. Regulation 48 asks for the manufacturer's type, acceptance and routine test certificates when required, and site tests on apparatus above 650 V as per the relevant standards, and it lets the inspector ask for more. For a 1 MW plant that means:

• earth resistance for each pit and for the combined system, since regulation 121(2) asks for adequate interconnected pits, welded not bolted;
• insulation resistance of DC strings, LT cables and HT cable after laying;
• transformer tests and relay trip tests against the settings on the drawing;
• surge protection, earth-fault and insulation monitoring as listed in regulation 121(3);
• interlock checks between grid, DG and solar;
• calibration certificates for the instruments, because regulation 33 expects calibration by a government-authorised or NABL-accredited laboratory.

Our CEIG readiness calculator turns a list like this into a gap check.

What happens on inspection day, and where do files get returned?

Karnataka's published procedure is typical of what most inspectorates do. The completion report is signed by the licensed contractor and supervisor. At inspection, the owner's representative and the supervisor attend with licences, permits and test instruments. Defects are listed, rectified and reported back before approval. The department's flow chart also shows an observation-letter loop at the drawing stage, where the application is returned for answers and resubmission.

We have not found a published count of reasons for rejection, so treat the following as what the checklists test, not as statistics: drawings that differ from the built plant, missing earth readings, instruments without calibration certificates, licences not endorsed to the contractor, protection settings that do not match the relay schedule, and an unapproved addition. Regulation 45(6) also requires written approval or self-certification for any later addition or alteration before it is connected, so a 200 kW extension next year starts a new file. Periodic inspection then follows under regulation 32, at a period the state sets and never above five years.

How Secured Engineers helps

We design the plant in-house and file the Fire NOC, CEIG and DISCOM net-metering applications in-house, so the drawing set, the transformer specification and the protection schedule come from one team. MEPF and solar can be delivered under one contract, which helps where the plant ties into DG changeover and fire systems. We work from our Noida (Delhi NCR) and Ludhiana offices, across 535+ projects in 18+ states, with 89.77% repeat clients. For states outside our confirmed delivery list we mobilise from Noida and Ludhiana, and this article is a buyer's guide, not a promise about what a given inspectorate will approve.

To have your drawing set and test records reviewed before filing, see our CEIG approval consultancy, message us on WhatsApp, call +91 70099 85817, or ask for a free proposal for your plant.