Solar for IT Parks and Office Buildings: Sizing, Roof, Approvals and Payback (50 kW+)

An IT park or office building has a large daytime load, mostly air-conditioning, but a small roof for that load, so rooftop solar usually covers a modest share of the bill. Size the plant to the usable roof, then decide how the savings reach whoever pays, since owners, tenants and the maintenance company often differ.

How much can the roof supply?

A low-rise campus of a few buildings can host a meaningful plant. A multi-storey tower has a roof far smaller than its floor area, and its load is the floor area times the cooling and plug load. The roof therefore sets a ceiling on the plant and the plant covers only part of the load.

The BEE's Energy Conservation and Sustainable Building Code 2024 (ECSBC) applies to commercial and office buildings with connected load of 100 kW or more, or contract demand of 120 kVA or more. Its clause on renewable energy systems asks for on-site generation capacity meeting at least 4% of total contract demand of the building on an annual basis, or covering a minimum of 50% of the available roof area, whichever is feasible, for ECSBC compliant buildings. That 4% figure is a fair picture of how little of a tower's load the roof serves. State governments notify and enforce the building code, so check whether yours has made it mandatory for your building.

1. Measure the usable roof. Take out lift machine rooms, water tanks, HVAC condensers and chillers, cooling towers, DG exhausts, antennas and the shade they cast. The shadow-free area calculator helps, and the plant area calculator converts kW to area.
2. Read the bills. Note monthly kWh or kVAh, maximum demand, sanctioned load and the tariff category.
3. Find the daytime share. A day-shift office is almost all daytime. An IT park running 24x7 for global clients has a night load that solar will not touch, so its daytime share may be lower than you expect.
4. Take the smallest of the daytime base load, the cap on sanctioned load and the usable roof. The sanctioned load calculator shows the cap.

What if the roof is too small?

The Green Energy Open Access Rules, 2022 lowered the open-access threshold to 100 kW and set approval in 15 days or deemed grant, according to the Ministry of Power's annual report. Our guide to open-access solar explains the options.

Which approval route applies by size?

• Net metering within the state limit. The central rules allow net metering up to 500 kW or the sanctioned load, according to PIB, and Punjab and Haryana's 2021 regulations apply that ceiling, with Punjab limiting non-domestic AC capacity to 70% of sanctioned load. Both cap annual generation at 90% of consumption, which a day-load office will normally stay under. Since February 2024, a feasibility study for systems above 10 kW has a 15-day limit with deemed approval.
• Above it or off-site. Gross metering, open access or group captive.
• Tall buildings. CEA 2023 regulation 38 covers multi-storeyed buildings above 15 metres: the state notifies the connected load and voltage above which the Electrical Inspector inspects, and the owner gives 30 days' notice before supply starts or restarts after six months. Rooftop plants on such buildings must also be shown to the fire authority; see Fire NOC.

What is specific to an office or IT park?

• Tariff category. In Punjab's FY 2025-26 tariff order, IT units covered by the state's notification are under the large supply industrial schedule, while ordinary offices fall under non-residential supply. The rate you avoid, and so the payback, depends on the category. Your bill shows which.
• Landlord, tenants and CAM. Most towers bill tenants for electricity through sub-meters and recover common-area costs as CAM charges. Who gets the solar saving depends on whose meter the plant feeds. A plant on the landlord's common-area meter reduces CAM charges, which are shared with tenants; a plant on tenant meters requires a shared-metering route. Group and virtual net metering exist in some states; ask your DISCOM. Whether a landlord can pass on solar power as a charge is a legal question for your DISCOM and lawyer.
• HVAC-driven load. Cooling follows the sun, so the daytime load matches generation well. Check chiller and VRF schedules; a shift in chiller timing can raise or reduce self-use.
• RCC roofs. Waterproofing must be protected. Ballasted or non-penetrating structures avoid drilling; where fixing penetrates, the waterproofing contractor should reseal. Check parapet height and wind loads on high roofs with the roof load calculator.
• Roof access and heat. HVAC plant, DG exhaust and fire-fighting equipment live on roofs. Keep maintenance paths and escape routes clear.
• Time of Day. The Ministry of Power's June 2023 amendment sets solar-hour tariffs 10% to 20% below normal for commercial and industrial consumers with demand of 10 kW and above from 1 April 2024, which lowers the value of midday units. Use your actual tariff order.

How do you judge the payback?

Payback is cost divided by the yearly saving. The saving is units used on site times the avoided rate, plus credited exports under the state's rules. For an office, the self-use share is high, so the avoided rate is the main variable, and it falls if Time of Day bands lower the daytime rate. Our published C&I band is ₹24,000–32,000 per kW excluding GST, with larger plants typically nearer the lower end; the 100 kW and 250 kW pages give working numbers. What moves a price inside the band is roof type and height, structure, waterproofing detail, cable run to the inverter room and interconnection voltage. Use the solar calculator for a first figure, then ask for a site-specific proposal.

How Secured Engineers helps

We design the plant in-house and file the DISCOM net-metering application, and the Fire NOC and CEIG files where required, ourselves. MEPF and solar can be carried under one contract, which suits a building that needs chillers, panels and fire fighting alongside the plant. We work from offices in Noida (Delhi NCR) and Ludhiana, on 535+ projects across 18+ states, with 89.77% repeat clients. See also commercial solar EPC.

Send your bills, roof plan and sanctioned load, and we will say what the roof and the cap allow and which shared route suits your tenancy. Start from solar for factories and large buildings, then message us on WhatsApp, call +91 70099 85817, or ask for a free proposal.