A Petrol Pump with No Generator: 20 kW Hybrid Solar and Battery Backup at Adhiraj HP, Greater Noida

A fuel station cannot run on half its load

A petrol pump sells fuel through a chain of equipment. The dispenser pumps the fuel, but the sale also needs the dispenser controls, the billing terminal, the payment machine, the network connection and, after dark, the forecourt lighting. If any link in that chain loses power, the sale stops.

Many outlets cover power cuts with a diesel generator. Adhiraj HP has none. So whatever supplied power during an outage had to carry the whole station, take over without anyone switching it on, and do it every time the grid dropped.

Why ordinary on-grid solar would not have helped

A standard on-grid solar inverter switches itself off the moment grid power fails. This protection is called anti-islanding, and it exists so that a solar plant cannot keep feeding lines that line staff may be working on. The panels can sit in full sunlight and the station would still go dark.

Keeping a station running through an outage needs three things working together: a hybrid inverter that can form its own supply when the grid is absent, a battery to store energy, and a controller that decides, moment to moment, where power comes from. That is what we built here.

What we installed

• Solar array: 20 kWp of half-cut mono PERC modules on a raised steel frame above the sales building roof, clear of the forecourt, so no vehicle or customer space was used
• Hybrid PCU: Fuji Electric, 20 kW, managing solar, grid and battery power and supplying the station load
• Battery bank: twenty 12 V, 150 Ah lead-acid batteries connected in series to give 240 V DC, on steel racks in a dedicated room
• Storage: 240 V x 150 Ah = 36 kWh nominal
• Protection and distribution: isolation, earthing and switching between the PCU and the station distribution board, so the whole outlet is fed through the hybrid system

Connecting batteries in series adds their voltages while the ampere-hour rating stays the same. That is how twenty 12 V units become one 240 V bank matched to the PCU's battery input.

The 36 kWh figure is the nominal capacity on the label. Lead-acid batteries last longer when they are not drained completely, so the PCU stops discharging well before empty. The usable share is lower than 36 kWh, and that is a deliberate trade for battery life.

The solar array and the PCU are matched one to one: 20 kWp of panels on a 20 kW PCU. The PCU has room for the full midday output of the array, and the array is large enough to run the daytime load and recharge the batteries.

How the system runs through a day and a power cut

• Daytime, grid present: solar supplies the running load first, surplus solar charges the batteries, and the grid tops up whenever solar falls short
• Power cut: the PCU keeps supplying the station from the batteries and from whatever solar is available, so dispensing, billing and lighting carry on
• Grid returns: the PCU goes back to normal mode, and solar and grid recharge the batteries ready for the next outage

How long the batteries last in a power cut depends on how much the station is drawing at that moment and on whether the sun is up. A daytime outage with good sun lasts far longer than one at night, because solar is still feeding the load. For that reason we do not quote a fixed number of backup hours.

Maintained by the people who built it

A battery-backed plant is only as reliable as its batteries. At a station with no generator to fall back on, maintenance has to be routine rather than on call. Our five year CAMC covers:

• Battery checks: terminal condition and tightness, cleaning, electrolyte level on flooded cells, and cell by cell voltage readings to catch a weak unit early
• PCU checks: fault log review, charging settings, ventilation and cooling
• Solar array: module cleaning and inspection of the raised frame and its fixings
• Protection: earthing and isolator checks

What this means for other fuel stations

Solar at a petrol pump is usually judged on units generated. At a station without a generator, the more important measure is whether the forecourt keeps selling when the grid drops. That has to be designed from the full operating load of the station, not from the size of the roof.

The same approach suits other customer-facing sites where a short outage stops trade, such as retail outlets, clinics and small cold stores. The design questions do not change: what must keep running, for how long, and what supplies it when the sun is down.

Frequently asked questions