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What a factory roof in Bangladesh is worth
Power tariffs are up, and buyers with science-based targets want lower supplier emissions. We costed the roof most RMG factories already have.
US$123,000
a year sits on a 10,000 m² factory roof
- 4.5 yearssimple payback at a typical installed cost
- 875 tof CO₂ a year off the factory's Scope 2
The problem
Bangladesh exporters are under two pressures at once. Industrial power tariffs have risen sharply since 2022. The brands they sell to, many with science-based targets, now ask suppliers to cut the emissions from the electricity they buy, because those emissions sit in the brand's own Scope 3.
Most garment and textile factories have a large flat roof doing nothing. In daylight, when the sewing floors and cutting rooms run at full load, panels on that roof can supply part of the power directly, and every kilowatt-hour they make is one the factory doesn't buy from the grid.
We took a factory with 10,000 m² of usable roof, which carries about 1 MWp of panels once walkways and spacing are allowed for.
The working
Each line follows from the one before it. The inputs and their sources are listed further down, so you can redo it with your own numbers.
Cumulative cash from the roof
System size
usable roof ÷ roof area per kWp
= 10,000 m² ÷ 10 m²
= 1,000 kWp
What it generates
system size × specific yield
= 1,000 kWp × 1,250 kWh/kWp
= 1,250,000 kWh a year
Grid bill avoided
generation × tariff × (1 + VAT) ÷ exchange rate
= 1,250,000 kWh × BDT 11.56 × 1.05 ÷ 123.55
= US$122,805 a year
Simple payback
system size × installed cost ÷ yearly saving
= 1,000 kWp × US$550 ÷ US$122,805
= 4.5 years
Scope 2 cut
generation × grid emission factor
= 1,250,000 kWh × 0.70 kg CO₂/kWh
= 875 t CO₂ a year
The fix
The roof decides the project before the panels do, so a structural check comes first. After that, the factory's daytime load and its grid connection set how big the system should be. A system larger than the daytime load sends power back to the grid, and the rules for that differ from the rules for using it on site.
For a supplier reporting to buyers with science-based targets, the 875 tonnes is a cut it can document from metered generation, which is the kind of evidence buyers ask for.
What would change the answer
This is a simple payback. It leaves out panel degradation, maintenance, financing and tariff rises. Tariff rises shorten the payback, and degradation and maintenance lengthen it a little.
Installed cost depends on the roof and the supplier, so confirm it with local quotes before you rely on it.
Inputs and sources
- Usable roof area10,000 m²Assumption for a typical site
- Roof area per kWp10 m²/kWpAssumption for a typical site, includes walkways and spacing
- Specific yield1,250 kWh/kWp a yearBangladesh studies report 1,185 to 1,350
- Industrial daytime tariff, June 202611.56 BDT/kWhBERC revision June 2026 as reported
- VAT on grid power5%As reported with the June 2026 revision
- BDT per USD123.55 BDT/USDBangladesh Bank reference rates, 18 Oct 2026
- Installed cost550 USD/kWpAssumption for a typical site; confirm with local quotes
- Grid emission factor0.7 kg CO₂/kWhConservative; Ember 2023 data implies about 0.74
Services behind this example
Delivered remotely in Bangladesh and every other country we serve.
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