Getting the tilt angle right can meaningfully affect how much power your system generates over its lifetime.
The General Rule
For fixed-tilt rooftop systems (the vast majority of residential and commercial installations), the ideal tilt angle is approximately equal to the site's latitude. Noida, Greater Noida, Ghaziabad, Kanpur, Lucknow, and Prayagraj all sit roughly between 25° and 28° North latitude, so a tilt angle of around 25°–28° facing true south gives the best year-round generation.
Why South-Facing?
In the Northern Hemisphere, panels facing south receive the most consistent sunlight through the day. East or west-facing panels still work but generate somewhat less over a full day.
Flat Roofs vs Sloped Roofs
Most RCC (flat) roofs in this region use mounting structures that tilt the panels to the correct angle regardless of the roof's own slope. Tin or tiled roofs with an existing slope are assessed individually — sometimes it's more cost-effective to install panels flush with the existing roof slope even if it's slightly off the "ideal" angle, since the generation difference is often small (a few percent) compared to the extra structure cost.
Note: figures in this article are indicative estimates for planning purposes. AdityaOn confirms exact pricing, subsidy amounts, and generation figures for your specific site during a free consultation, since these depend on your roof, location, and current government rates.