Solar for Petrol Pumps: Why 24-Hour Load Profiles Make the ROI Obvious

There are very few commercial sites in India where the load curve maps onto the solar curve as cleanly as a petrol pump. That's the whole economic argument - and it's why pumps don't need battery storage to justify the investment.

The 24-hour load profile is the entire pitch

A typical urban petrol pump's load looks like this:

• 00:00 - 06:00 - Low: canopy lights, CCTV, office standby (~2-4 kW)
• 06:00 - 18:00 - High: dispensers, compressors, office AC, canopy lighting in monsoon, CCTV (~10-18 kW)
• 18:00 - 23:00 - Medium-high: dispensers + full canopy lighting (~10-15 kW)
• 23:00 - 24:00 - Tapering (~4-6 kW)

The site never turns off. But the daytime block - exactly when solar generates - is also the heaviest consumption block. That means a properly sized rooftop plant gets self-consumed in real time, with minimal export. High self-consumption = best-case economics, because every solar unit displaces a grid unit at the full retail tariff (₹8.5-₹11/unit for fuel-retail commercial tariffs in most states).

Why batteries usually don't pencil out

Pump owners frequently ask: "Should I add batteries to run the dispensers at night?"

For most sites, no. Here's the math:

• A 20 kWh Li-ion battery system adds ₹6-₹8 lakh to project cost
• It serves maybe 4-5 hours of nighttime load, ~80-100 units/day
• At ₹10/unit displaced, that's ₹800-₹1,000/day, or ~₹3 lakh/year
• Battery warranty: 8-10 years; payback on the battery alone: 6-8+ years
• The pump already has near-100% grid uptime in most cities

Batteries make sense for backup/UPS during outages (where the dispenser MUST run), not for shifting solar. That case is stronger on rural and highway sites with frequent outages. Most urban owners install a small UPS for the dispenser controller and call it done.

Sizing: 15-30 kWp for almost every pump

Pump type	Monthly bill	System size
Small highway pump	₹15–25k	10–15 kWp
Urban 4-dispenser	₹30–45k	18–25 kWp
Large urban / 24×7	₹50–80k	25–35 kWp

Sizing follows daytime consumption, not total - you don't want to chronically export to a low net-metering credit rate.

Canopy mounting constraints (this is where projects break)

The forecourt canopy is the obvious mounting surface. It's flat, shadow-free, and structurally over-engineered. But:

• No drilling on OMC-owned canopy without written approval from the oil marketing company (IOCL/BPCL/HPCL/Reliance/Nayara). Each OMC has its own approval process - start it before you sign the EPC contract.
• PESO clearance - minimum safe distances from underground fuel tanks and vent pipes apply to DC strings, inverters and ACDB locations.
• Ballasted (non-penetrating) mounts are often the only acceptable option on canopies. They add ~₹500-₹700/kWp to structure cost.
• DC isolators within 1 m of the array for emergency disconnection.
• Earthing tied into the existing forecourt LA, not a separate ground.

Realistic payback

For a typical 20 kWp urban pump:

• Installed cost: ~₹12-13 lakh (canopy ballast adds a premium)
• Generation: ~29,000-31,000 units/year depending on the state's irradiance
• Bill savings: ~₹3 lakh/year
• Payback: under 4 years without AD, ~3 years with AD for a profit-making dealership

The canopy is a power plant. Most owners just haven't been told yet.