Solar for Hospitals: Sizing, Roof, Approvals and Payback (50 kW+)

A hospital should size solar from its daytime bill, not from its roof. Wards, ICUs, HVAC and lighting run through the day, so a 50 kW to 500 kW rooftop plant is usually consumed on site. Up to 500 kW or the sanctioned load, whichever is lower, it normally runs under net metering. A grid-tied plant does not back up critical loads in an outage; the DG set and UPS still do.

How do you size a hospital solar plant from the bill?

Four numbers decide the size, and the smallest one wins. A hospital differs from a factory in one useful way: its base load never stops. Chillers, AHUs, lifts, sterilisers, imaging and ward lighting keep daytime demand high on Sundays and holidays too, so the usual factory worry of exporting on weekly offs is smaller. Check it from the data instead of assuming it.

As a planning figure for north India the site's calculators use about 120 units per kW per month. A 100 kW plant would generate about 12,000 units a month. Compare that with your weekday daylight consumption before you fix the size, then test options in the solar calculator. The bill header matters more than the equipment list.

Where does the array go on a hospital roof?

A hospital roof is rarely empty. Chillers and cooling towers, AHUs and exhaust fans, DG exhausts, water tanks, lift machine rooms, antennas and sometimes a helipad compete for the same terrace, and every tall item casts a shadow that a flat drawing hides. Do a shadow study before layout; the shading note on why yield estimates differ explains the method.

• Access and isolation. Regulation 121 of the CEA (Measures relating to Safety and Electric Supply) Regulations, 2023 asks for clear pathways of at least 75 cm with handrails for roof access and emergency exit, walkways between rows, a manual disconnection switch outside the AC combiner box, and inverters near the panels at the periphery of the building. It also asks for fire detection and automatic suppression to the relevant standards.
• Helipad. NBC 2016 Part 6 says elevated helipad structures are designed to the latest guidelines of the Directorate General of Civil Aviation and the ICAO Heliport Manual. Keep panels and structures out of the approach and take-off area, and ask the helipad designer or the aviation authority before you place anything near it. We have not assumed a clearance distance.
• Structure and waterproofing. Roofs over operating theatres, labs and sterile stores cannot tolerate leaks. Choose ballasted or clamp systems where penetrations are a risk, and read our notes on roof penetrations and older roofs.
• Other places. Parking structures and campus land can carry panels when the roof cannot; see carport solar.

Which approval route applies to a hospital plant?

The Ministry of Power's annual report for 2021-22 records that an amendment to the Electricity (Rights of Consumers) Rules, 2020 raised the net-metering limit from 10 kW to 500 kW. The Rules let the state commission decide the details, and states often tie the cap to the sanctioned load, so confirm yours with the DISCOM.

Under regulation 34 of the 2023 safety regulations, generating units above the capacity your state has notified, renewable ones included, are inspected by the Electrical Inspector before commissioning. Hospitals are also named in regulation 38, which requires halogen-free flame-retardant power cables in hospitals irrespective of height, so the AC cabling from inverter to panel should be specified accordingly. The module rules (ALMM and DCR) change with dates; our notes on the ALMM List-II commissioning window are the place to check.

What risks are specific to a hospital?

• Solar is not backup. A grid-tied inverter stops when the grid fails, by design, so the plant will not hold an ICU on supply. Critical loads stay on UPS and the DG set. Backup would need a hybrid inverter and batteries, which is a separate design; see the battery storage page.
• DG interaction. If the plant must run with the DG set, the control scheme has to stop solar from overloading or back-feeding the generator. Read what goes wrong with solar and DG sets.
• Tie-in outages. A hospital cannot switch off for a day. Connection to the main LT panel has to be planned department by department, with a tested changeover and clinicians told in advance. Our note on hospital MEP phasing covers the approach.
• Power quality. Imaging equipment, UPS units and variable-speed drives add harmonic content. Ask for a power quality check at the point of connection.
• Fire and insurance. Share the rooftop DC layout with your fire officer and insurer before you build; rooftop solar DC fire safety lists what they usually ask. The hospital fire NOC route is in fire NOC for a hospital.
• Tariff category. Hospitals may sit in a different tariff category from industry in your state. Use the energy charge on your own bill, not a general figure.

How do you work out payback?

Cost comes from the published C&I band of ₹24,000–32,000 per kW excluding GST. Savings come from the energy charge you avoid on each unit you use yourself. Solar does not normally reduce fixed or demand charges, so do not use the whole bill. Illustration for 100 kW at mid-band (₹28,000 per kW), so the arithmetic is visible: cost ₹28 lakh excluding GST; generation 100 x 120 x 12 = 1.44 lakh units a year; maintenance taken at 1% of cost a year; every unit used on site; exports valued at zero.

The rates are illustrative inputs, not hospital tariffs. The table ignores GST, tax treatment, module degradation, tariff changes and any roof strengthening or HT works. Put your own rate into the payback calculator, and read the size pages for 100 kW and 250 kW.

How Secured Engineers helps

Secured Engineers designs solar in-house and files the CEIG and DISCOM net-metering applications in-house. MEPF and solar can sit under one contract, which matters on a hospital roof where the plant, the fire system and the HVAC share the same terrace. The company works from offices in Noida (Delhi NCR) and Ludhiana and reports 535+ projects across 18+ states and 89.77% repeat clients. Our hospital record is the full MEPF package for JMH Prime in Karol Bagh, New Delhi, covering HVAC, electrical, plumbing and fire fighting; that record does not include a solar plant.

Start from our solar page for large consumers, or send twelve bills and a roof photograph on WhatsApp, call +91 70099 85817, or ask for a free proposal.