Efficiency is about area, not superiority
Higher module efficiency means more watts per square metre. On an area-constrained roof this is valuable. On a roof with surplus space, a slightly lower-efficiency module with better commercial terms can be the more sensible choice.
Degradation and warranty
Every module loses output over time. What matters is the guaranteed performance at year 25 and the credibility of the manufacturer standing behind that guarantee. A warranty is only as good as the entity honouring it.
Temperature coefficient in Indian conditions
Rooftop module temperatures in Gujarat summers run far above test conditions. A better temperature coefficient translates into meaningfully higher real-world generation during the hottest, highest-irradiance months.
Bifacial is site-dependent
Bifacial modules capture reflected light on the rear face. The gain depends heavily on mounting height, tilt and the reflectivity of the surface below. On a close-mounted residential roof the benefit is limited; on elevated structures it can be significant.
