In a solar rooftop system, the solar panels are installed in the roof of any residential, commercial, institutional and industrial buildings. This can be of two types (i) Solar Rooftop System with storage facility using battery, and (ii) Grid Connected Solar Rooftop System.
Such rooftop system has battery as storage facility. The solar electricity is stored in the battery and can be utilized during night also when the sun is not available.
In grid connected rooftop or small SPV system, the DC power generated from SPV panel is converted to AC power using power conditioning unit and is fed to the grid either of 33 kV/11 kV three phase lines or of 440/220 Volt three/single phase line depending on the capacity of the system installed at institution/commercial establishment or residential complex and the regulatory framework specified for respective States.
These systems generate power during the day time which is utilized fully 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 power from the grid.
Such rooftop systems can be installed at the roofs of residential and commercial complex, housing societies, community centers, government organizations, private institutions etc.
The average cost of grid connected rooftop solar systems is about Rs. 75 per watt or Rs.8.0crore per MWp capacity.
There are provisions ofconcessional import duty/excise duty exemption, accelerated depreciation and tax holiday for setting up of grid connected rooftop power plants.
Department of Financial services has instructed to all Public Sector Banks to encourage home loan/ home improvement loan seekers to install rooftop solar PV plants and include cost of system in their home loan proposals. So far, nine PSBs namely Bank of India, Syndicate Bank, State Bank of India, Dena Bank , Central Bank of India, Punjab National Bank, Allahabad Bank, Indian Bank and Indian Overseas Bank have given instructions to extend loan for Grid Interactive Rooftop Solar PV Plants as home loan/ home improvement loan.
The rooftop solar systems from 1 kWp upto 500 kWp or in combination can be set up on the roofs.
About 10sq.m area is required to set up 1 kWp grid connected rooftop solar system.
According to a study conducted by TERI, a potential of 124 GWp SPV Rooftop plants has been estimated in the country. This can be achieved through active supports from the States.
The grid connected rooftop system can work on net metering basis wherein the beneficiary pays to the utility on net meter reading basis only. Alternatively two meters can also be installed to major the export and import of power separately. The mechanism based on gross metering at mutually agreed tariff can also be adopted.
In feed-in-tariff the Government offers a tariff for purchase of the solar power generated from such plants.
Net metering mechanism is more popular among States.
So far, 20 State/UT Regulators from Andhra Pradesh, Chhattisgarh, Delhi, Gujarat, Haryana, Karnataka, Kerala, Odisha, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh, Uttarakhand and West Bengal, Andaman & Nicobar, Chandigarh, Dadra & Nagar Haveli, Daman & Diu, Lakshadweep, Pondicherry and Goa have notified policies that include promotion of grid connected rooftop solar systems with net metering. Regulation from the State Electricity Regulatory Commission is also required to allow net metering/ feed-in-tariff.
The Projects under these guidelines fall within two broad categories i.e.(a) the projects connected to HT voltage at distribution network (i.e. below 33 kV) (b) the projects connected to LT voltage i.e. 400/415/440 volts (3-phase) as the case may be or 230 volts (1-phase). Accordingly, the projects may be under the following two categories.
Category 1: Projects connected at HT level (below33kV) of distribution network
The Projects with proposed installed capacity of minimum 50 kW and upto 500 kW and connected at below 33kV shall fall with in this category. The projects will have to follow appropriate technical connectivity standards in this regard.
Category 2: Projects connected at LT level (400 Volts-3 phase or 230 Volts-1 phase)
The Projects with proposed installed capacity of less than100kW and connected of the grid at LT level (400/ 415/ 440 volts for 3-phase or 230V for1-phase) shall fall within this category.
There can be many possible business models, some of which can be considered are as follows:
i. Solar Rooftop facility owned, operated and maintained by the consumer(s).
ii. Solar Rooftop facility owned by consumer but operated and maintained by the 3rd party.
If the 3rd party implements the solar facility and provides services to the consumers, combinations could be:
i. Arrangement as a captive generating plant for the roof owners
The 3rd party implements the facility at the roof or within the premise of the consumers; the consumer may or may not invest as equity in the facility as mutually agreed between them. The power is then sold to the roof owner.
ii. Solar Lease Model, Sale to Grid
The 3rd party implementing the solar facility shall enter into a lease agreement with the consumer for medium to long term basis on rent. The facility is entirely owned by the 3rd party and consumer is not required to make any investment in facility. The power generated is fed into the grid and the roof top owner gets a rent.
i. Solar installations owned operated and maintained by the DISCOM
The DISCOM may own, operate and maintain the solar facility and also may opt to sub contract the operation and maintenance activity. The DISCOM may recover the cost in the form of suitable tariff. The electricity generation may also be utilized by DISCOM for fulfilling the solar renewable purchase obligation.
ii. Distribution licensee provides appropriate viability gap funds
The DISCOM may appoint a 3rd party to implement the solar facilities on its behalf and provide appropriate funds or viability gap funds for implementing such facility.
The programme is being implemented through multiple agencies for rapid up-scaling in an inclusive mode. These agencies are:
(i) State Nodal Agencies(SNAs)
(ii) Solar Energy Corporation of India (SECI)
(iii) Channel Partners:
a) Renewable Energy Service Providing Companies (RESCOs)
b) System Integrators
c) Manufactures of any component of the Solar Plants
d) Project developers
e) Vendors/ suppliers of solar equipment
f) Reputed and relevant NGOs of National level
(iv) Financial Institutions/Financial Integrators
The Financial Institutions like NABARD, National Housing Banks, Other Banks, IREDA, SECI, etc.
(v) Other Govt. Departments/Agencies
The other Govt. Departments/Agencies i.e., Railways, Defense/Para Military Forces, Local Government Bodies including Municipal Corporations/Municipalities, PSUs, Institutions, Development Authorities, DMRC, State Departments interested in directly implementing the programme