FAQ’s
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In a grid-connected rooftop or small solar photovoltaic (SPV) system, the DC power generated from the solar panel is converted to AC power using a power conditioning unit/inverter and is fed to the grid.
- Solar PV Modules/Solar Panels – Convert solar energy to DC electrical energy. Most common type is Crystalline Silicon. Panels are connected as per required capacity.
- Inverter – Converts DC to AC and synchronizes with the grid.
- Module mounting structure – Holds panels in place and withstands weather. Can be fixed or tracking type.
- Bi-direction Meters – Measure energy injected to and drawn from the grid.
- Balance of System – Includes cables, junction boxes, breakers, lightning protection, etc.
A 1 kW rooftop system generally requires 10 sq. metres of shadow-free area. However, actual area requirements may vary depending on module efficiency and placement.
Solar modules need uninterrupted sunlight for optimal power generation. Even partial shadow can reduce performance and lifespan significantly.
Rooftop solar PV systems can be installed on any type of roof having sufficient load-bearing capacity.
On a clear sunny day, a 1 kWp solar power plant can generate 4 to 5.5 units in a day.
No, energy generation varies with temperature, sunlight availability, and other environmental factors.
- Plant Location
- Quality of equipment used
- Number of sunshine hours
- Workmanship
- PV module tilt angle and orientation
- Module cleaning
- O&M activities, etc.
No. Over time, solar modules degrade and their energy output reduces gradually.
- Saving on electricity bill by the consumer
- Utilization of available vacant roof space, no additional land required
- Low gestation period
- No additional requirement of transmission and distribution (T&D) lines
- Reduces T&D losses as power consumption and generation are collocated
- Improvement in tail-end grid voltages and reduction of system congestion
- Long-term energy and ecological security by reduction in carbon emissions
- Better management of daytime peak loads by DISCOM/utility
- Helps in meeting Renewable Purchase Obligations (RPOs)
Cost of system and subsidies
The current benchmark cost of grid connected rooftop solar systems can be seen in notification section at
https://solarrooftop.gov.in/notifications/view
Central financial assistance (CFA) is available only for residential sector grid-connected solar rooftop projects:
- CFA @ 40% for capacity up to 3 kWp
- CFA @ 20% for capacity beyond 3 kWp and up to 10 kWp
- CFA @ 20% for GHS/RWA projects up to 500 kWp (limited to 10 kWp per house)
No. Consumer pays only the remaining amount after subtracting eligible CFA from the L1 project cost.
Click here for advisory.
Consumers should pay only according to the L1 rates decided by DISCOMs. If a vendor charges more, report it to your DISCOM.
State subsidies may be available through your local electricity distribution company. Visit
this portal for DISCOM-specific info.
No, MNRE works through DISCOMs who handle vendor empanelment. You can apply online through DISCOM portals available at
this link.
Consider the following when evaluating vendors:
- System price
- Warranties on system and components
- Expected energy generation and guarantees
- Local service availability
- Reference installations and customer feedback
Since the system is connected via net metering, DISCOM bills you only for net units (imported units minus exported solar units).
It's rare to get a ₹0 bill as some minimum charges apply. However, electricity charges can be eliminated with a well-designed RTS, and in some states, revenue from surplus power is allowed.
Metering arrangement for solar rooftop
All solar PV systems generate power only during daytime when sun is available. In net metered systems, the generated power is utilized for self-consumption, and excess power is exported to the grid as long as grid is available. In case, where solar power is not sufficient due to cloud cover etc., power is drawn from the grid to power the loads. A bi-directional or net meter records the energy flow in both the directions and at the end of billing period net energy used is calculated. The beneficiary has to pay for only the net energy used.
In gross metering the power generated from the Rooftop Solar plant is only fed to the grid. The system owner gets paid by the DISCOM for such exported power at a pre-decided tariff.
Connections in net billing RTS are similar to net metering. However, at the end of the billing cycle (normally a month) any excess energy in the grid shall not be carried forward like in net metering, but shall be purchased by the DISCOM as per pre-decided tariff. Therefore, energy banking in the grid is only within a billing cycle.
Yes, the plants which are not connected to the grid are normally called behind the meter plants and MNRE subsidy is not available for such plants even for residential sector. However, it is required to follow rules and regulations specified for this purpose by the state authorities.
Business model for solar rooftop system
CAPEX Model: Here, the system is owned by the consumer himself and he bears the cost of the system.
RESCO Model: Here, the entire system is owned by the 3rd party project developer. The consumer only purchases the generated energy by paying pre-decided tariff on a monthly basis as per Power Purchase Agreement (PPA). Responsibility of O&M for the system lifetime (25 years) is also with the developer.
A simple payback period can be calculated by using the rooftop calculator available at:
https://solarrooftop.gov.in/rooftop_calculator
Installation of solar rooftop system
Residential consumers and Group Housing Society can apply for installation of solar rooftop system through the online portal of DISCOMs. The link for the online portal of DISCOMs is mentioned
https://solarrooftop.gov.in/grid_others/discomPortalLink
The interested beneficiary may install the solar rooftop systems through project developers/system integrators/manufacturers, etc. after taking necessary approval from DISCOMs within the capacity limit as laid down in the order of respective State Electricity Regulatory Commission/Joint Electricity Regulatory Commission of the respective States/UTs.
The RTS under any framework like net or gross metering can be installed by the electricity consumer. So, if you have electricity connection in your name, you pay the electricity bill regularly, and you have the permission from the owner to use the roof for solar rooftop installation, you can install the RTS.
With several common rooftops available in a society, there is a great potential for harnessing solar energy through rooftop PV systems. The energy generated from these systems is used to offset the common loads of the society (common lighting, lift, pumps, etc.). A Net Meter shall be provided against the Single Point Delivery (SPD) common meter of Cooperative Group Housing Society (CGHS). In this, the society ultimately gets benefitted in terms of reduced monthly electricity expenses.
The system is easy to be dismantled and reassembled elsewhere. So, it can be shifted to your new residence.
Yes. Only indigenously manufactured PV modules with indigenous solar cells can be used in Solar PV systems for subsidised sector projects. For reference, as per the ALMM list 10th March 2021 Clause 4 IV- Link:-(https://mnre.gov.in/img/documents/uploads/file_f-1615380939218.pdf). However, there is no such limitation in case the project is installed without any subsidy.
Operation and maintenance of solar plant
Solar PV modules used in solar power plants/systems must be warranted for their output peak watt capacity, which should not be less than 90% at the end of 12 years and 80% at the end of 25 years. The mechanical structures, electrical works including power conditioners/inverters/charge controllers/maximum power point tracker units/distribution boards/digital meters/switch gear/storage batteries, etc., and overall workmanship of the SPV power plants/systems must be warranted against any manufacturing/design/installation defects for a minimum period of 5 years.
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 activities typically may include but are not limited to the following:
- Module cleaning is required periodically (dust, bird dropping, and other debris can cause decrease in power generation). Periodicity depends on local conditions like dust, birds, air pollution, etc.
- Checking module connection integrity
- Checking junction boxes / string combiner boxes
- Inspecting mechanical integrity of mounting structures
- Tightening cable connections that have loosened
- Replacing blown fuses
- Repairing lightning damage
- Repairing equipment damaged by intruders or during module cleaning
The solar modules are made up of toughened or tempered glass top and so are not easily broken due to monkeys or any falling objects. These can be broken if deliberately someone throws stones. Guarding of module surface with wire mesh is one solution for monkey menace, but not recommended because this regularly casts shadow on the modules.
General information about solar rooftop
India is endowed with vast solar energy potential. About 5,000 trillion kWh per year energy is incident over India’s land area, with most parts receiving 3-5 kWh per sq. m per day. Based on the availability of land and solar radiation, the potential of solar power in the country has been assessed to be around 750 GW.
National Institute of Solar Energy (NISE), An Autonomous Institute under the Ministry of New and Renewable Energy, has estimated a potential of 43 GW for Grid-Connected RTS in the country.
The Government of India has set the target of installing 40,000 MW of Rooftop Solar (RTS) Power by the year 2022. State-wise tentative targets are available on the website link: https://solarrooftop.gov.in/grid_others/phase2SanctionList
The details on capacity sanctioned under Phase-II of the RTS scheme can be seen on the following link: https://solarrooftop.gov.in/grid_others/phase2SanctionList
Electricity regulatory commissions have notified the regulations for all States /UTs. Amendments, if any, may kindly be seen at the websites of the respective State Electricity Regulatory Commission/Joint Electricity Regulatory Commission.
The Approved List of Models and Manufacturers of Solar Photovoltaic Modules (ALMM) is available at https://mnre.gov.in/img/documents/uploads/file_f-1615380939218.pdf. However, the ALMM order in respect of List I (Modules) shall be applicable to all such bids whose last date of bid submission is on or after 10.04.2021.
Yes. The Ministry of New and Renewable Energy has created a knowledge portal for knowledge dissemination among Consumers/DISCOM Officials/Bankers/SERCs, etc., which can be accessed by using the URL: https://solarrooftop.gov.in/grid_others/knowledge