Dear Sir ,
I think you are new in solar or led lighting filed,
As its the road in the farm and lux for farm is enough from 15 to 20 lux and in twelve watt led will give around 35 lux from 12 feet total pole will be 5 meter above ground level it will be 12 feet.
If you can any doughts about any thing in renewable energy please clear your doughts.
There are different wattages for application as solar light in part, solar light in appartment coman area or street light in rural.