In its order on LT connectivity and net-metering for rooftop solar systems, TNERC said that electricity generated from a solar system and injected into the licensee’s grid should be capped commercially at 90 per cent of the electricity consumption by the eligible consumer at the end of a settlement period and excess energy generated beyond the cap would be treated as lapsed.
This means a domestic consumer would be able to install a rooftop solar system whose generation capacity should not exceed 90 per cent of their annual power consumption. Though the commission had proposed a cap of 200 per cent in its draft order, it has brought down the cap to 90 per cent in line with the guidelines issued by the forum of regulators, said a senior Tangedco official.
To ensure grid stability, the commission has fixed a cap on grid penetration for solar PV system. “At the local distribution level connectivity to rooftop solar systems should be restricted to 30 per cent of the distribution transformer capacity on the basis of the first come first served,” it said.
An official explained that if a distribution transformer has a capacity of 100 kilowatt, maximum of 30 Kw solar system would be allowed to be installed to ensure grid security issues arising out of possible reverse flow of electricity in the local grids.
TNERC also made installation of a meter measuring solar power optional for those who had availed state’s capital subsidy of Rs 20,000. The bi-directional meter, which records import an export of energy would replace the existing meter. But it said grid interactive PV system with battery backup is not under the purview of it.