No Drilling, 11 Floors Up: 208 kWp of Rooftop Solar on Six AIIMS Hostels, New Delhi

Why this was not an ordinary rooftop job

On paper this is a mid-sized on-grid system. On site it combined four constraints that rarely come together.

• Height: the hostels are high-rise blocks of 7 and 11 floors. Every module, every length of steel and every bag of cement had to go up the building and come down again as packaging and waste.
• Old buildings: the blocks are ageing structures with waterproofed roofs. AIIMS did not permit any drilling, core cutting or anchor bolts into the roof slabs. A single leak into a resident's room was not an acceptable risk.
• Occupied hostels: residents lived in every block throughout the work. Noise, dust, lift use and material storage all had to fit around daily hostel life.
• Controlled working hours: every worker needed security clearance, and work was allowed only within approved hours, 9:00 AM to 5:30 PM. Extensions and Sunday working had to be requested in writing, month by month.

Electrical design

The plant totals 208 kWp DC from 379 Navitas modules of 550 Wp, feeding 200 kW of inverter capacity. Each hostel has its own inverter, sized to its own roof. Nothing crosses between buildings, and each block can be isolated and maintained without touching the others.

Strings were worked out for each building so that every string sits inside the inverter's input window, and a separate single line diagram was prepared for each hostel. The DC and AC distribution boxes were built by Efab Power Control in CPRI-certified metal enclosures, with Type II surge protection, L&T MCCBs and class 0.5 metering.

Designing a structure that never touches the slab

With drilling and anchoring ruled out, the structure had to be held down without piercing the roof or its waterproofing.

MGetEnergy designed an elevated galvanised steel frame standing on cast concrete pedestals, each 400 mm by 400 mm by 300 mm in M15 concrete. The legs are bedded into the pedestals with reinforcement bars, and the pedestals are bonded to the roof surface with adhesive. Nothing is drilled or anchored into the slab, so the roof and its waterproofing stay intact. Separate structure drawings, bills of material and pedestal footing layouts were produced for Hostels 14 and 15 and for Hostels 16 to 19, because the roof plans differ.

Raising the array clear of the roof also keeps parapets, water tanks and other rooftop services accessible for the hostel maintenance staff.

Inverters

The plant runs on six Luminous Nxi series three-phase on-grid string inverters: an Indian brand with a service network close to Delhi and acceptance by Delhi DISCOMs. MGetEnergy is a certified Luminous Solar Solutions Partner.

In each hostel the inverter sits on the top-floor landing between its DC and AC distribution boxes, with the armoured cables clamped neatly along the wall.

Getting material up 11 floors

Moving material to roofs up to 11 floors high, in buildings occupied by residents, required a dedicated arrangement. A mini lift was installed and used exclusively for material movement to the top floor. Every load was raised on properly guided ropes to keep it steady and clear of the building face, and all lifting was carried out under special supervision.

Materials were staged block by block within the permitted working hours. The concrete pedestals were cast in place on each roof in manageable batches, with curing time allowed before the steel frame was erected.

Working inside a live campus

A named team of eight, from project manager and site in-charge to electrician, mason, plumber and helpers, was cleared by AIIMS security. Permission for working hours was renewed in writing through the project, and Sunday working was requested to keep the programme on track. Work stayed within AIIMS norms, with minimal disruption to the residents.

Result

• Six hostel roofs, 208 kWp, grid-connected
• Completed on 17 November 2025, under four months from the start of work
• No drilling, no anchoring and no disturbance to the roof waterproofing
• AIIMS issued a completion certificate stating that the work had been found good and satisfactory

What this means for other institutions

Hospitals, universities and government campuses often have the same mix: tall old buildings, strict roof rules, residents or patients on site, and tight security. The approach used at AIIMS, an elevated structure on adhesive-bonded pedestals, one inverter per building, and a written plan for access and hours agreed before work starts, carries straight across to them.

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