FAQ: Grid Connected Solar Rooftop System
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.. This can be of two types
(i) Solar Rooftop System with storage facility using battery, and
(ii) Grid Connected Solar Rooftop System.
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 power conditioning unit/Inverter and is fed to the grid either of 440/220 Volt three/single phase line or of 33 kV/11 kV three phase lines depending on the capacity of the system installed at residential, institution/commercial establishment and the regulatory framework specified for respective States. 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 crystalline, thin film, CIGS, CdTe, HIT, etc. 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, tracking system (if required), earthing system ,circuit breaker,fuses etc.
4. What are the models for implementation of Rooftop PV systems?
CAPEX Model : Here, the entire system is owned by the rooftop owners and he bears the cost of the Soalr system. Responsibility of O&M for the system lifetime (25 years) is also with the rooftop owner. Developer is responsible for installing the system and initial 2 years O&M and five years warranty.
RESCO Model : Here, the entire system is owned by the developer. Responsibility of O&M for the system lifetime (say about 25 years) is also with the developer. Rooftop owners may consume the electricity generated, for which they have to pay a pre-decided tariff on a monthly basis. Excess generation may be exported to the grid, subject to availability of requisite state regulations.
5. Which model is best for me?
For consumers that have adequate manpower/expertise for O&M, rooftop access concerns, availability of funds upfront, CAPEX model is better. Consumers in states that have net-metering regulations can take benefit of the same in case they have substantial excess generation.
On the other hand, consumers who prefer not to take responsibility for the system O&M, do not have rooftop security concerns and prefer to pay on a monthly basis rather than bulk upfront payment may choose to go for RESCO model.
6. 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 basis only. Alternatively two meters can also be installed to measure the export and import of power separately. The mechanism based on gross metering at mutually agreed tariff can also be adopted.
7. What is Gross Metering
In gross metering the energy generated from the spv plant is feed to the grid . In lieu to the energy fed to the grid , they are paid a feed in tariff.
8. What are the advantages of Grid-Connected Rooftop Solar System?
• Benchmark cost of Roof top Solar system: Rs. 60,000/- per kW
• Generally , a 1 kW system generates about 1200- 1500 units per year
• Savings per annum Rs. 6000 to Rs. 7500 per year ( considering average tariff of Rs. 5 per unit)
• Payback period: Rs. 5 - 7 years
( *Payback period may further reduce in case there is any change in higher tariff slabs of electricity bill of the consumer due to net reduction in monthly electricity units consumed from Grid or if electricity tariff increases)
Benefits under RESCO mode:
• In a RESCO model the entire system is owned by the project developer and rooftop owners used to pay a monthly pre-determined tariff based on their consumption of electricity to the project developer.
• Responsibility of operations and maintenance is on the developer.
9. General procedure for installation of Rooftop Solar system for beneficiary
How much capacity one can install?
Dependent on availability of budget with the consumer, electrical load requirement of the beneficiary, electrical connected load, availability of shadow free rooftop area, maximum capacity allowed by respective State Regulatory Commission etc.
Request for grid connectivity/ Net meter:
The selected vendor will assist the consumer in submission of forms of respective DISCOMs for grid connectivity/net-metering connections etc. After submission of application form the DISCOM conducts feasibility study, charges application /net metering fees, conducts site visits, installs net-meter and provides grid connectivity/net metering after commissioning of the project. In some cases, inspection by Chief Electrical Inspector to the Govt. (CEIG) may also be required.
(Note: The above procedure may vary from State to State depending on State policy
10. How much area is required for a 1 kW rooftop Solar PV system?
A 1 kW rooftop system generally requires 10 sq. metres 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.
*However this varies from State to State/project developers/tenders etc. For the year 2019 Benchmark costs may be revised during April, 2019.
(iii) The Distribution Companies agree to allow grid connectivity and purchase the electricity on feed-in-tariff or through net metering arrangement.
11. Who are the main stakeholders of the Grid Connected Rooftop Programmes ?
• State Nodal Agencies (SNAs)
SNAs are the Government Agencies at State level that work for the promotion and development of renewable energy programmes/projects in their respective states.
• Distribution Company (DISCOM)
DISCOM interprets and implements the provisions of the policy and regulations, thereby allowing customers to interconnect their RTS system to the grid. In the process, the DISCOM ensures overall safety, adherence to the overall technical guidelines, and follow commercial processes etc..
• Chief Electrical Inspector to Government
The Chief Electrical Inspector to the Government (CEIG) ensures safety compliance and operations of RTS system as per the provisions laid out in the Electricity Act,
2003 and Indian Electricity Rules, 1956. The CEIG’s involvement with respect to the process is on two counts: firstly, approval of drawings and design documents, secondly, pre-commissioning inspection of the installed RTS plant for issue of
‘Charging Certificate’.
• Financial Institutions/Banks
The financial Institutions and financial Integrators i.e., NABARD, National Housing Banks, other Banks, IREDA, etc.
12. Kindly name the States having notified the solar rooftop policy?
Please see the details in website https://mnre.gov.in/file-manager/UserFiles/solar-rooftop-states-policy-tariff.htm . Amendments if any may kindly be seen at the respective websites of the State Renewable Energy Department.
13. What efforts is the Government making to provide loans for solar rooftop systems?
Department of Financial services has instructed to all Public Sector Banks (PSB) 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.
14. What are the O&M aspects of a grid-connected rooftop solar PV system?
Compared to most other power generating technologies, solar PV systems have very low maintenance and servicing requirements. However, suitable maintenance of a PV plant is essential to optimise energy yield and maximise the life of the system.
Some of the maintenance activity typically may include but not limited to the following:
• Only Module cleaning is required (dust, bird dropping and other debris can cause decrease in power generation)
• Other items may be checked periodically if so required as sted
• Checking module connection integrity
• Checking junction / string combiner boxes
• Inspecting mechanical integrity of mounting structures
• Vegetation control
• Tightening cable connections that have loosened
• Replacing blown fuses
• Repairing lightning damage
• Repairing equipment damaged by intruders or during module cleaning
*The above mentioned FAQs are for informative purpose only*