The Tamil Nadu Electricity Regulatory Commission (TNERC) has passed an order granting an exemption to high tension (HT) consumers installing rooftop solar projects for parallel operation and captive use without the export of power to the grid.

Parallel operation is the simultaneous execution of two or more operations.

However, the Commission mentions that it is subject to technical feasibility, safety norms, and collecting parallel operation charges as applicable.

The order was passed in response to Tamil Nadu Generation and Distribution Corporation Limited’s (TANGEDCO) petition requesting the commission to permit the parallel operation to HT consumers with solar power projects in a premise with capacities not more than 1 MW without the need for a separate feeder up to the financial year (FY) 2021-22.

Background:

In 2013, some of the HT consumers requested the TANGEDCO to connect their proposed rooftop or ground-mounted solar power projects, within their service connection premises in their high tension or low tension (LT) networks without the export of energy to the grid.

As there were no technical issues, TANGEDCO started to facilitate parallel operation approval to all those HT consumers subject to conditions, of which a few include:

• The entire energy generated should be consumed within the premises, and power should not be exported to TANGEDCO. If any power is exported, it would not be considered towards the adjustment against consumption or payment
• The generator must pay the parallel operation charges per month for each MW capacity. The charge is applicable as the generator is availing parallel operation with the grid for captive use of solar power without availing open access

Subject to several conditions and as there was no technical issue found, TANGEDCO started facilitating parallel operation approvals to all such HT consumers.

TANGEDCO also stated that applications for a combined capacity of ~15 MW for the establishment of rooftop or ground-mounted solar power projects within the HT consumer premises for parallel operation without export, are received but could not be approved “as these HT consumers are not fed with a separate feeder.”

It argues that all the HT consumers may not be having a separate or dedicated feeder, and it was not viable for TANGEDCO to facilitate separate breaker arrangements to the HT consumers.

In its order, the commission noted that the cases described by petitioners are consumers who wish to set up solar projects in the premises for the in-house loads with no evacuation of power but with connectivity to the grid.

“There seems to have been a misinterpretation of an existing regulation requiring a separate feeder is applicable to the cases of generators who evacuate or inject power to the grid.  Therefore, the question of granting any exemption by the commission does not arise,” it noted.

The commission further observed that the licensee could use its discretion to approve parallel operation with or without a dedicated feeder in case of projects which do not export power to the grid depending on technical feasibility and observing safety norms.

However, there needs to be a restriction in approving the parallel operation of generators, which are not connected exclusively through separate feeders to limit the effects of any inadvertent injection of energy in the distribution network, the commission observed.

“It is seen from the petition that approvals have been accorded for project capacities up to 10 MW to consumers who have dedicated feeders, the highest of which is 4 MW.  About 50 applications of solar generating projects of capacities up to 15 MW are reported to be kept pending as the consumers do not have separate feeders.  It is noted that TANGEDCO has accorded approvals for parallel operation of solar power projects without insisting on separate feeders prior to the issue of amendment to Regulation 8.   The effects of these parallel operations on the distribution network have not been discussed in the petition,” the order added.

However, keeping the central government’s solar target for 2022, the commission has allowed TANGEDCO to grant parallel operation to HT consumers in a premise with capacities up to                    1 MW without the need for a separate feeder up to FY 2021-22 keeping certain conditions in mind that have been discussed above.

Earlier this year, the state issued new net metering guidelines for solar rooftop consumers as part of its Solar Policy 2019. Per the guidelines, an eligible consumer can install the maximum capacity of solar rooftop up to 100 percent of his contracted demand with the distribution licensee.