Cooling That Rides Through Power Cuts: 250 kW Solar and 600 kWh Battery at a Mushroom Plant in Mainpuri

A mushroom plant cannot pause its cooling

Fresh mushrooms spoil fast, and the growing rooms run to controlled temperature and humidity around the clock. A power cut is not an inconvenience here. Cooling that stops puts the crop and the stored stock at risk, and a canning line that stops mid-batch means product that has to be checked or written off.

Running on a 250 kW generator

Before solar, every cut meant starting the site's 250 kW diesel generator. That kept the plant alive but came with all the usual problems: a fuel bill that rose with every cut, running hours and maintenance on the generator, and diesel pilferage, which is hard to control on a large rural site.

The owner wanted the critical loads off diesel during outages, not just cheaper daytime power.

Why ordinary on-grid solar would not have helped

A standard on-grid inverter shuts down the moment the grid fails. It has to, so that it cannot feed a dead line. On-grid solar alone would have cut the daytime bill and done nothing during a power cut, which was the whole problem.

Riding through cuts needs a hybrid power conditioning unit, a battery, and control that decides which source feeds the load.

What we installed

• Solar array: 250 kW on the tin shed roof of the plant
• Hybrid power conditioning: Fuji Electric, 250 kW, matched to the array
• Battery: gel cells, 2 V each, on steel racks in a dedicated battery room, 600 kWh nominal
• Protection, distribution and the changeover to the critical load circuits

We chose gel because the battery room sits in a hot climate and has to run for years with little attention. Gel cells are sealed, need no topping up and tolerate heat better than flooded batteries.

To protect their life, gel banks are normally cycled to about half their depth, so the usable energy is about 300 kWh of the 600 kWh nominal. That is what sets the two hours at 150 kW.

How the system runs through a day and a power cut

• Daytime, grid present: solar feeds the plant first and charges the battery with what is left
• Power cut: the hybrid unit carries the critical loads, cooling and canning, from solar and the battery together
• Grid returns: the system goes back to normal mode and the battery recharges for the next outage

In a daytime cut the sun stretches the backup well beyond two hours. At night, at about 150 kW, the bank carries roughly two hours.

Estimated diesel avoided

This is an estimate, not a metered figure. At about 150 kW of critical load, a 250 kW diesel generator burns roughly 0.3 litres per kWh, or about 45 litres an hour.

With 2 to 3 hours of cuts a day now carried by the battery, that is about 90 to 135 litres a day, or about 33,000 to 49,000 litres of diesel a year that the generator no longer burns during outages. This does not count the daytime diesel the 250 kW of solar also displaces.

Maintained for its first five years

We looked after the plant for its first five years under a CAMC that ran from 2021 to 2026. It covered:

• Battery checks: terminal condition and tightness, cleaning, and cell by cell voltage readings to catch a weak cell early
• Hybrid unit checks: fault log review, charging settings, ventilation and cooling
• Solar array: module cleaning and inspection of the mounting and fixings
• Protection: earthing and isolator checks

A client who came back

In 2022 the same owner asked us to solarise Kapil Muni Children Academy at Bewar: a 25 kW hybrid system with a 36 kWh battery. A repeat order from a client who has lived with our work for a year says more than any brochure.

What this means for other food processors

For a plant where a power cut spoils product, size the battery for the loads that must not stop and the hours they must run, not for the solar array. Here the critical load is about 150 kW out of a 250 kW system, and that number, not the array size, set the battery.

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