1. What is a Solar Rooftop System?

In a solar rooftop system, the solar panels are installed in the roof of any residential, institutional, social, Government, commercial, industrial buildings etc. .

2. What is a Grid Connected Solar Rooftop System?

In grid connected rooftop or small SPV system, the DC power generated from SPV panel is converted to AC power using Inverter and is fed to the grid either of 440/220 Volt three/ single phase line installed at residential, institution/commercial establishment. These systems generate power during the day time which is utilized by powering captive loads and feed excess power to the grid as long as grid is available. In case, where solar power is not sufficient due to cloud cover etc., the captive loads are served by drawing balance power from the grid.

3. What are the main components?

Solar PV Modules/Solar Panels – The Solar PV modules/Solar Panels convert solar energy to electrical energy. They are available in different technologies such as Mono Crystalline, Poly Crystalline, thin film, CIGS, CdTe, HIT, etc. Poly Crystalline Solar PV panels are most common in use on roof tops.

Inverter – Inverter converts DC output of Solar PV panels into AC power.

Mounting structure – The mounting structure is the support structure that holds the Solar PV panels

Balance of System – These consist of cables, switchboards, junction boxes, meters, structures, earthing system ,circuit breaker, fuses etc.

4. What is net-metering?

The grid connected rooftop system can work on net metering basis wherein the beneficiary pays to the utility on net meter reading i.e. the difference between the import and the export energy, if the imported energy is more than the exported energy. If the exported energy is more than the imported energy the utility will pay to the beneficiary for the net energy exported. This concept is applicable to the solar applications registered before 25.03.2019. Thereafter, net feed-in method of billing is applicable.

5. What is net feed-in scheme?

Under net feed-in scheme for the applications registered on or after 25.03.2019, the surplus/excess energy generated that is unutilized and that flows to the grid at the end of the billing period will be calculated at a tariff fixed by the Hon’ble Commission and credited to the consumer’s account. The energy that is imported from the grid by the consumer will be calculated at the appropriate retail tariff and the monetary value of imported energy debited from the available credit on account of exported energy in the respective billing period. Any credit available in the account of the consumer after debiting value of imported energy will be carried over to the next billing period for adjustments against subsequent billing. If the amount to be debited is higher than the credit in a billing period, the consumer will have to pay the difference in charges..

6. How much capacity one can install?

Depending on the sanctioned demand of the existing service, load requirement of the beneficiary and availability of shadow free rooftop area, the beneficiary may decide the capacity upto 150 kW under LT service.

7. Who will do the feasibility analysis?

Feasibility process will be waived off for 3KW of Solar applied load.More than 3 KW feasibility process will be done by TANGEDCO.

8. Request for grid connectivity/ Net meter

On installation of the PV plants by the vendor, the vendor/consumer will send the readiness report to TANGEDCO. After completing the inspection by AEE/O&M for installations of capacity of 10 KW and by CEIG for installations of capacity of above 10 KW , on receipt of inspection report, bi-directional meter will be installed by TANGEDCO for providing grid connectivity.

9. How much area is required for a 1 kW rooftop Solar PV system?

A 1 kW rooftop system generally requires 10 sq. meters of shadow-free area. Actual sizing, however, depends on local factors of solar radiation and weather conditions, efficiency of solar module, shape of the roof etc.

10. What are the advantages of Grid Connected Rooftop Solar (RTS) System?

  • Cheaper and environment friendly electricity.
  • Excess energy can be fed into the grid with tariff as determined by the State Electricity Regulatory Commissions .
  • Electricity generation occurs at consumption center thus, saving transmission and distribution losses
  • Lower payback period.
  • 25 years guaranteed lifespan of the solar photovoltaic panels
  • Highly modular
  • 25 years guaranteed lifespan of the solar photovoltaic panels
  • Subsidy is available from the Central Government for domestic category (residential) of LT consumers.
  • Quick installation

11. Can a Grid Connected RTS System generate electricity during the night? How do we get power during the nights/monsoons?

Grid Connected RTS System cannot generate electricity during the night. In the absence of generation during night/monsoon, power supply will be fed from the grid.

12. How much electricity does a Grid Connected Rooftop Solar (RTS) System Generate?

The Grid Connected Rooftop Solar (RTS) system installed on a roof will generate an average of 4 to 5 units of electricity per kWh per day.

13. Do I need a permission from the Municipal Authorities or Pollution Control Board?

Not required.

14. What kind of electrical loads can be connected with Rooftop Solar (RTS) System?

All kind of loads, including inductive, capacitive and lighting load in category of LT services except hut and agriculture can be connected with Rooftop Solar (RTS) system.

15. What is the lifespan of the RTS plant?

A Grid Connected Rooftop Solar (RTS) power plant has a lifespan of 25 years.

16. Are there any incentive/subsidy available? Where shall I contact for availing subsidies?

17. Where shall I submit the application for subsidy?

  • Applications for non- subsidised Solar Rooftop projects shall be submitted through TANGEDCO’s Unified Solar Rooftop portal.
  • Consumers under residential category who are willing to avail Subsidy under PM Surya Ghar Muft Bijli Yojana scheme shall have to register and apply through National Portal. National Portal Reference number will be generated .By using the National Portal Reference number consumer has to apply through TANGEDCO’s Unified Solar Rooftop Portal(USRP) and Application charges should be paid through TANGEDCO’s Payment Portal.
  • 18. From where can I find the status of my application?

  • Status of applications for non- subsidised Solar Rooftop projects can be traced through TANGEDCO’s Unified Solar Rooftop portal(USRP).
  • Status of applications under residential category applied through National Portal (PM Surya Ghar Muft Bijli Yojana ) can be traced through National portal and After the application submitted to TANGEDCO,The status can also be traced through Unified Solar Rooftop Portal(USRP).
  • 19. Before installing a Grid Connected RTS System do I need to inform the Power Utility (TANGEDCO)? How can we approach?

  • Yes
  • Consumer can register directly through Unified Solar Rooftop Portal if they are not willing to avail CFA.
  • Consumers under residential category who are willing to avail Subsidy under PM Surya Ghar Muft Bijli Yojana scheme shall have to register and apply through National Portal. National Portal Reference number will be generated .By using the National Portal Reference number consumer has to apply through TANGEDCO’s Unified Solar Rooftop Portal(USRP) and Application charges should be paid through TANGEDCO’s Payment Portal.
  • 20.How are the billing and payments made by TANGEDCO for the grid connected solar rooftop services.?

  • For the applications registered before 25.03.2019 , under Solar Net Meter Category based on Tamil Nadu Solar Policy 2012 the following billing procedure is adopted:
  • In any billing cycle if the energy imported by the consumer is more than the energy exported to the grid over and above his self consumption, then the import kwh and export kwh are adjusted and the bill will be raised for payment by the Consumer as per existing norms and the applicable service connections tariff. In any billing cycle, if the energy exported exceeds energy imported, the surplus of export Kwh over import Kwh shall be carried over to the next billing cycle for adjustment against the import Kwh of that billing cycle.

  • For the applications registered on or after 25.03.2019 , under Solar Netfeed-in Category based on Tamil Nadu Solar Energy Policy 2019 the following billing procedure is adopted:
  • Energy settlement will be done on monthly basis. The electricity generated by the RTS will be utilised for the self consumption by the consumer. The excess unutilized energy flowing into the grid and recorded in the export register of the meter will be credited into the consumers account at a tariff fixed by the Regulatory Commission. The energy that is imported from grid by the consumer will be calculated at the appropriate retail tariff and the monitory value of imported energy debited from the available credit on account of exported energy in the respective billing period. Any credit available in the account of the consumer after debiting the value of imported energy will be carried out to the next billing period. If the amount to be debited is higher than the credit in a billing period, the consumer will have to pay the difference in charges. At the end of the settlement period monitory value of surplus generation, if any will be settled by TANGEDCO.

    21. Is CEIG Approval Compulsory?

    For installed PV systems of capacity above 10 KW, CEIG approval is compulsory.

    22. What are the Electricity Standards to be followed to install Grid Connected SRTPV System?

    Consumer has to comply with CEA standards and relevant safety standard as followed by CEIG.

    23. What are the documents necessary for registering application for solar rooftop systems?

    Bill Receipt and Applicant Photo

    24.What is the time limit for effecting Solar Net feed-in services?

    Time schedule as specified by the TNERC schedule and as per the norms in vogue will be followed..