On a tunnel-ventilated shed in June, the fans are the whole argument. How a poultry farm's cooling load shapes the solar and battery design, what a shed roof will and will not carry, and what to ask before signing.
Bangladesh's poultry industry produces over 1.5 billion broiler chickens and approximately 23 billion eggs a year, and a modern commercial farm runs on electricity: tunnel ventilation fans, evaporative cooling pads, automated feeders, drinkers and lighting. The number that should drive the whole design is not the monthly bill. It is that a single power outage of 30 minutes during peak summer heat can cause significant flock mortality. Everything else about a poultry solar project follows from that.
That last point is worth dwelling on, because it is unusual. Most Bangladeshi industrial loads only partly overlap with the solar day. A poultry shed's cooling demand rises and falls with ambient temperature, which rises and falls with the same sun that is driving the array. The array is largest at the hour the fans are working hardest.
| Farm size | Birds | Solar plant | Battery storage | Monthly saving | Payback |
|---|---|---|---|---|---|
| Small farm | 10,000 birds | 20 kWp | 20 kWh | approx. BDT 20,000-30,000 | 4-5 years |
| Medium farm | 50,000 birds | 80 kWp | 60 kWh | approx. BDT 80,000-1,20,000 | 4 years |
| Large farm | 200,000 birds | 300 kWp | 200 kWh | approx. BDT 3,00,000-4,50,000 | 3.5 years |
The right architecture for a poultry farm is a hybrid system: grid-tied solar with battery storage. During the day the array powers all farm loads and charges the batteries. At night, or when the grid fails, the batteries carry the critical ventilation and lighting loads. Hybrid inverters of the type specified on these projects, such as the Growatt SPH or Solis ranges, transfer in under 20 milliseconds, fast enough that the fans and lights do not even flicker.
What the battery has to carry is a narrower list than most owners assume. Feeders and drinkers can wait. The fans, the cooling pad pumps, the shed controller and its alarm cannot. Write that schedule down with the farm manager, decide how many hours of hot-weather ventilation you are buying, and size the bank to that. A quotation that gives you a kWh figure without naming the loads it is meant to hold has not done the work.
Poultry sheds are long, low-pitch corrugated metal roofs on light steel portals, usually standing in open ground. Three things follow from that. First, the purlins were sized for sheeting and little else, so purlin spacing and section need checking before anyone quotes a mounting structure. Second, an isolated shed in open country sees higher wind uplift than the same roof would in a built-up area, and the racking and its fixings must be designed for it rather than copied from a factory job. Third, a shed roof spans a controlled environment, so a leak from a badly sealed penetration is a bird welfare problem as well as a maintenance one. Clamp-based racking that grips the sheet without penetrating is the sensible default.
The array layout also has to respect the shed itself. Tunnel ventilation depends on the inlet and ridge arrangement working as designed, and modules must not obstruct inlets or change the airflow pattern over the roof. Agree the layout with whoever specified the ventilation before it is fixed.
Most commercial farms sit in rural areas, so the application goes to BREB through the local Palli Bidyut Samity, with SREDA-format paperwork: the single-line diagram, module and inverter datasheets with IEC certification numbers, roof plan, a recent bill and trade licence. Expect a technical committee review and site inspection before the No Objection Certificate is issued, and expect a rural application to need more chasing than a Dhaka one. The bi-directional meter is fitted by the utility at the consumer's cost.