In a Solar Rooftop System, the major investment is its installation cost and has a minimal maintenance cost and no fuel cost. A 5 KW Solar PV System has average pay back period of approximately 3 to 4 years.
An off-grid system is not connected to the electricity grid and therefore requires battery storage. Off-grid solar systems must be designed appropriately so that they will generate enough power throughout the year and have enough battery capacity to meet the home's requirements, even in the depths of winter when there is generally much less sunlight. But it will cost significantly more compare to on grid.