We had installed a 4 KW On Grid solar roof top solar power plant at an NGO at Gondal. Solar PV modules of 300 Wp with quantity 14 no’s were used for this solar power plant. Today, PGCVL installed the solar meter and Bi-directional meter for monitoring the solar generation and give benefit of Net Metering to the user.
The system of Net Metering which is heavily promoted by (MNRE) Government of India and Gujarat Energy Development Agency (GEDA) in Gujarat works in following way:
Suppose user of on grid (without battery) solar power plant has a demand load of 2 KW mentioned on his Electricity Bill. Then as per prescibed norms, he can install upto maximum 50% capacity of on grid solar power plant. That means user can install 1 KW of solar power plant.
Shadow free area of approx. 130 square feet is required for installing solar photo voltaic modules of 1 KW.
Solar generation achieved on clear sunny day will be approx. 4 KWh (units) per day. Now if user operated fans, light, Television, refridgerator or other electrical / electronics gadgets during day time, then solar power will be used on priority basis, if there is any deficit of power, then Grid (power from PGVCL) power will be automatically used parallel with solar power.
Vice versa, if house of the Roof top on grid solar power plant user is closed during day time, then surplus solar power will be automatically exported to the Grid (PGVCL). Suppose solar power of 4 KWh (unit) generated from 1 KW solar power plant is exported to the Grid during day time due to non use by the owner of solar power plant during day time. If User consumes 6 KWh (unit) from Grid power during night, then he is liable to pay charges to electricity supplier like this : 6 – 4 = 2 KWh (unit).
This system of making payment to DISCOM (electricity supply company) on Net usage basis is called Net Metering.
In order to avail this benefit of Net Metering for Roof Top solar power plants, Two meters are installed by DISCOM (electricity supply company) at the premises of user. One is solar meter which monitors the solar power produced from the Solar PV modules and other meter is Bi-directional meter which is installed by replacing the old meter installed at the premises of user.
In Residential, institutional and social sectors, (MNRE) Government of India is providing 30% subsidy on the total cost of the Roof top solar power plant. Payback time of Roof top solar power plant for this segment is nearly 6 years.
In commercial or industrial sector, there is no direct subsidy available for Roof top solar power plant. But these sectors can claim Accelerated Depreciation of 40% in the first year of installation in India w.e.f. 1 st April 2017.