Power Department

Government of Sikkim

Frequently Asked Questions

A GRPV system comprises of electrical and electronic equipment such as solar modules, inverters, cables, switch gears, etc. When these components are connected together and placed on the roof of buildings exposed to sunlight, the system starts generating electricity. A GRPV system generates electricity that can either be injected directly into the distribution grid or used for captive consumption at the installation premises.

GRPV Systems are of two types:

  • GRPV systems without battery storage.
  • GRPV systems with battery storage
  • Cheaper and environment friendly electricity.
  • 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.
  • Requires minimal maintenance.
  • 25 years guaranteed lifespan of the solar photovoltaic panels.
  • Subsidy is available from MNRE.
  • Highly modular.
  • Quick installation.

No, GRPV systems cannot generate electricity at night. If a battery is used to store energy, then this energy can be used at night.

In case of a GRPV system, power supply will be available from the electric grid whenever there is an absence of generation by the system.

Under net metering, electricity generated by the GRPV system is first utilized by the consumer to meet their internal/captive requirements. Excess electricity, if any, is exported to the grid. Subsequently, when the consumer imports power from the grid, the exports are adjusted against the imports, lowering the electricity bill.

A net meter (bi-directional meter) records the energy imported from the grid to meet the load and surplus energy exported to the grid after consumption. Both energy import and export is recorded in the net meter. The difference between export and import readings is the actual energy consumed/delivered.

The excess generation being injected into the grid is net off on monthly basis. The final settlement is done at the end of every financial year as per the norms set by Sikkim State Electricity Regulatory Commission (SSERC).

For each kWp, the GRPV system installed on a South-facing roof will generate 4 to 6 units of electricity per day. However, depending upon the weather conditions, the energy generation reduces by around 20 percent for an East or West facing roof.

A GRPV system is made up of different components. These include PV modules (groups of PV cells), grid tied inverters, circuit breakers, relays, energy meters (net/gross), module mounting structures (MMS), cables, etc.

According to the SSERC Grid Interactive Solar Power Regulations 2014, the capacity of the solar energy system to be installed at the premises of any eligible consumer shall not be less than One kilo Watt peak (kWp) and shall not exceed One Mega Watt peak (MWp) subject to the following specifications:

S. No. Type of connection Supply voltage Specification of output of the solar energy systems
1 Low Tension Single Phase 240 V 240 V, 50Hz
2 Low Tension Three Phase 415 V 415 V, 50 Hz
3 High Tension 11000 V 11000 V, 50 Hz

It is also to be ensured that the capacity of the solar energy system relating to the connected load or contract demand at each voltage level shall be in conformity with the provisions specified in the Sikkim State Electricity Regulatory Commission Supply Code, as amended from time to time.

Most roofs are strong enough for solar installation without any reinforcement. However, in case of larger systems, it is suggested to consult a qualified Structural Engineer.

Benchmark cost of the GRPV system depending on the size is given in the following table: /* MNRE benchmark costs for Grid Connected Rooftop Solar Power Plants for the Year 2019-20Benchmark Benchmark Cost (Rs/Wp) Benchmark Cost (Rs/Wp) for Special category states which includes the north eastern states, Hilly Special States of Uttarakhand, Himachal Pradesh, J&K and UTs of Andaman & States Nicobar Island and Lakshadweep
Above 1 kW and upto 10 kW 54 59
Above 10 kW and upto 100 kW 48 53
Above 100 kW and upto 500 kW 45 50

*The above benchmark costs are inclusive of total system cost and its installation, commissioning, transportation, insurance and applicable fees & taxes.

Currently, the following business models are in vogue namely, self-owned (capital expenditure [Capex] model) and Renewable Energy Service Company (RESCO) model and third-party owned model. “RESCO” means an energy service company which provides renewable energy to the consumers in the form of electricity.

Under Capex Model, consumers develop a solar rooftop plant within their premises to own, operate, and generate electricity for self-consumption and sell excess electricity to the utility (under net metering) or sell entire electricity to the utility (under gross metering). Generally, self-owned business model is preferred for its simplicity. However, this model also has disadvantages such as high capital cost for the consumer and high technology and performance risk.

Under RESCO Model, a RESCO builds, owns, and operates GRPV plants in the premises of a consumer to generate and sell electricity to the consumer. Consumer may further engage in a net metering or gross metering arrangement with the DISCOM.

In RESCO, consumer does not invest in the GRPV power plant. However, a RESCO developer invests and sets up the system. RESCOs are specialized solar developers; they can handle technology and operation risks in a better way. However, RESCO model faces several challenges such as power off-take risks, contractual risks, etc.

Under Third Party Model, a third party builds, owns, and operates GRPV plants on a rooftop and sells the generated electricity directly to the DISCOM at FIT.

Suitability of these model depends on one’s ability to meet the costs. However, RESCO model is more suitable for institutional, commercial, and industrial consumers needing higher capex.

Yes. All applications related to GRPV shall be processed through USRWP. Upon submission of DISCOM Application for Interconnection, Power Department of Sikkim will check the technical feasibility and provide a response through the USRWP. Applicants can register themselves through USRWP and apply online directly using relevant forms and format to the approving authority.

“Any consumer in the area of supply of the Distribution Licensee may install in his/her premises, the solar energy system, either owned by him/her or by a third party.”- Regulations for grid interactive distributed solar energy systems, SSERC.

A maximum of 1,000 kWp at a single location is allowed under net metering.

No. DISCOM will provide bi-directional energy meters on cost basis for consumers to avail net metering facility.

Energy settlement will be done within the applicable settlement period as per prevalent regulations.

Consumer must comply with the Central Electricity Authority (CEA) standards and relevant safety standards as followed by Electrical Inspector (EI).

Yes, some banks provide loans especially for solar rooftop systems. This information is available on the USRWP.