If you run a factory or a warehouse, the honest answer to "does solar make sense here?" is usually yes, a daytime industrial load under a big flat roof is close to an ideal match. The more useful question is whether your particular building is ready, and where the surprises are hiding. Run these twelve checks and you will know, before a single panel is ordered, whether you have a clean install or a project that needs groundwork first.
The building itself
1. Roof type and usable, shadow-free area
Start with what you can actually cover, not the total roof, but the clear, shadow-free area left after skylights, ridges, walkways, vents and maintenance setbacks. As an indicative rule of thumb, budget around 90–100 sq ft per kWp, so an indicative 1 MW plant wants roughly 90,000–100,000 sq ft. Metal sheet roofs are friendliest; RCC and asbestos carry caveats. Sanity-check the fit in our rooftop estimator. Pass = enough contiguous clear area for your target; fail = size to the roof, not the ambition.
2. Structural capacity to IS 875
This is the check cheap proposals quietly skip. An array adds permanent dead load and, more importantly, changes how wind uplift acts on the roof, panels behave like sails. The building must carry both, assessed against IS 875 (Part 3) for your location's wind speed and terrain; on older sheds, purlin spacing and corrosion matter as much as the original design. Pass = an engineer confirms the roof takes the combined load with margin; fail = you need strengthening, lighter mounting, or a smaller layout.
3. Shading and obstructions
Panels are unforgiving about shadows. A single chimney, water tank, taller block or line of trees can drag down a whole string for hours, and shadow patterns shift with the seasons. The check is a year-round shading analysis, not a glance on a sunny afternoon. Pass = the roof stays clear through the main generating hours; fail = obstructions force the layout to route around them, or the yield needs an honest haircut.
4. Roof orientation and tilt
In India, south-facing tilt captures the most energy, but few industrial roofs are built for it. Flat RCC roofs let you tilt panels to an optimal angle; sloped metal roofs take panels flush to the sheet, so the roof's own pitch and direction decide the yield. East–west layouts are viable too, trading a little peak for a flatter curve. Pass = a sensible annual yield for your latitude; fail = a poor aspect that quietly costs units every year.
5. Waterproofing and warranty
A rooftop plant lives up there for 25 years, so how it is fixed down matters as much as the panels. Non-penetrative (ballasted) mounting avoids drilling and protects an existing waterproofing warranty; anchored mounting bolts into the structure and must be sealed properly, or it becomes a leak two monsoons later. Pass = a mounting method that suits the roof and keeps warranties intact; fail = drilling a warrantied membrane with no sealing detail and no one owning the leaks.
The energy and the meter
6. Load profile and daytime consumption
Solar generates during the day, so it pays back fastest when you use the power as it is made. The number that matters most is the share of your consumption in daylight hours. A two-shift factory running 9 to 6 is a beautiful fit; a cold store that runs hardest overnight is not, at least not without storage. Pass = a high daytime load that self-consumes most of the generation; fail = a night-heavy profile where you export cheaply and buy back dear.
7. Sanctioned load headroom
Most DISCOMs cap installable solar as a percentage of your sanctioned (contracted) load, commonly a large fraction of it, but the exact ceiling varies by state and connection type. If your sanctioned load is 750 kVA, a 1 MW plant may not be permitted without revising the connection. Pass = your target sits comfortably under the limit; fail = you are over the cap and must downsize, enhance the sanctioned load, or look at open access.
8. Electrical room and evacuation space
The panels are only half the plant. Inverters, AC and DC boards, cabling and metering all need a dry, ventilated, accessible home, with a clean cable route from roof to inverter to your main panel. Cramped or already-full electrical rooms are a common, unglamorous bottleneck. Pass = space and a sensible cable path exist; fail = no room for the balance-of-system, meaning civil work before install.
9. DISCOM feasibility and net-metering eligibility
The project has to be blessed by the utility: a feasibility application, interconnection approval, and confirmation of which metering regime applies, net metering, net billing, or gross metering, because that choice reshapes the economics entirely. Eligibility, feeder queue and settlement all differ by state. Pass = the connection is feasible and you know exactly how exported units are credited; fail = feeder constraints, an unfavourable rule, or a category that is not eligible.
10. Tariff category and escalation
Solar's value is whatever grid unit it displaces, so a high tariff is your friend. Industrial and commercial HT consumers on an indicative ₹8–11 per unit see far quicker paybacks than a subsidised category, and because tariffs tend to climb year after year, every self-generated unit is worth a little more over time. Pass = a healthy tariff with a rising trend; fail = a low or subsidised rate that stretches the payback out.
The commercial fit
11. Commercial model fit
There is no single "right" way to own a plant, only the one that fits your balance sheet. CAPEX means you own it outright and keep every rupee of savings after payback; RESCO / OPEX means a developer funds and operates it while you buy the power per unit at a discount; open access sources solar off-site when the roof cannot hold enough. Our case studies show how each has played out. Pass = a model that matches your cash position and holding period; fail = forcing one that strains capital or locks you into terms you will regret.
12. O&M access and cleaning water
A plant is only as good as its upkeep, and upkeep needs two boring things: safe access and clean water. Panels lose output as dust builds up, so you need a practical way onto the roof and water to wash the array, especially in dusty industrial belts. Sort out walkways, ladders, fall protection and cleaning water before, not after, commissioning. Pass = the roof is safely accessible and water is on hand; fail = a plant no one can reach or clean, quietly bleeding yield.
The 12-point check
- Roof type & usable shadow-free area (indicative ~90–100 sq ft per kWp)
- Structural capacity to IS 875, dead load plus wind uplift
- Shading & obstructions across the full year
- Roof orientation & tilt for your latitude
- Waterproofing & warranty, non-penetrative vs anchored mounting
- Load profile, share of consumption in daylight hours
- Sanctioned load headroom vs the DISCOM cap
- Electrical room & evacuation / cable-route space
- DISCOM feasibility & net-metering eligibility
- Tariff category & historical escalation
- Commercial model fit, CAPEX, RESCO/OPEX or open access
- O&M access & a water source for cleaning
What a clean pass looks like
You will rarely tick all twelve first time, and that is fine, most "fails" have a fix: strengthen a purlin, resize to the roof, enhance a sanctioned load, choose net billing over net metering. The point is to surface those fixes now, as cheap decisions on paper, not later as expensive surprises on a live site. And every figure here stays indicative on purpose, the only number worth acting on comes from a proper study of your own building.