What should I check when selecting a solar street light supplier in India?

I am comparing different suppliers for a solar street lighting requirement and would like some practical advice from people who have experience with these systems.
When selecting a solar street light supplier in India, should the main focus be on the product specifications, manufacturer background, price, warranty or after-sales service?
For a project, I think it is important to understand the complete system rather than only looking at LED wattage. The solar panel, battery, controller, LED module and housing all seem to have an impact on the overall performance.
I would also like to know how buyers normally calculate the required lighting capacity. Does it depend mainly on road width and pole height, or should factors such as pole spacing, sunlight availability and required operating hours also be considered?
Another question is whether it is better to purchase directly from a manufacturer or through a local supplier.
If anyone has experience with solar street lighting projects in India, what points would you recommend checking before placing an order?