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
(I) Solar Rooftop System with storage facility using battery, and
(ii) 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 daytime which is utilized by powering captive loads and feed excess power to the
grid if grid is available. In case, where solar power is not enough due to cloud cover etc., the
captive loads are served by drawing balance power from the grid.
- 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.
CAPEX Model: Here, the entire system is owned by the rooftop owners and he bears the
cost of the Solar 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 must pay a pre-decided tariff on a
monthly basis. Excess generation may be exported to the grid, subject to availability of
requisite state regulations.
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
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.
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.
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.
Benchmark cost of Roof top Solar system: Rs. 60,000/- per kW
- Central financial assistance: Rs. 18,000/- per kW
- Net cost to customer (CAPEX Mode): Rs. 42,000/- 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
- 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.
Application, where to apply:
Will be in shubh solar enterprises scope.
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.
The benchmark cost of grid connected rooftop solar systems for FY 2018-19 varies from Rs.
53 per watt – Rs. 60 per watt. The details are as follows:
Capacity Benchmark Costs (Rs. /Wp) *
Above 1 kW and up to 10 kW 60
Above 10 and up to 100 kW 55
Above 100 kW and up to 500 kW 53
(ref. notification in website: https://solarrooftop.gov.in/notification/Notification-
(Central Govt Subsidy is available on these Benchmark cost or tender cost established by
State Govt, whichever is lower.)
*However, this varies from State to State/project developers/tenders etc. For the year 2019
Benchmark costs may be revised during April 2019.
Eligible beneficiary interested to avail subsidy may directly apply to the implementing
agency (e. g. State Nodal Agency/SECI etc.) and get necessary approvals prior to installation
of RTS systems. The implementing agency needs to select vendors for installation of Rooftop
projects by adopting competitive bidding process. Sanction orders are given by MNRE to
these implementing agencies for the capacity of the rooftop solar systems planned to be
installed by them.
The implementing agency must submit complete project details online in the website
www.solarrooftop.gov.in for availing eligible service charges and incentives. The online
portal captures all details of the project, viz. capacity, project cost, address, district, State,
latitude, longitude etc.
MNRE does not sanction any project or subsidy directly to the beneficiaries.
The sanctions would be issued based on online project proposal submitted by implementing
State Subsidy support is also available in a few states which varies according to the state
Yes. Only indigenously manufactured PV modules should be used in Solar PV systems power
plants for subsidised sector. The scheme requires the project proponents to adhere to the
national/ international standards specified by the Ministry from time to time. See detailed
technical specification in website (https://mnre.gov.in/file-manager/UserFiles/Scheme-
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 12years 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 over all workmanship of the SPV power plants/ systems
must be warranted against any manufacturing/ design/ installation defects for a minimum
period of 5 years.
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.
- World Bank to SBI (USD 620 Million). See loan product details at https://www.sbi.co.in/webfiles/uploads/files/SBI_WORLD_BANK.pdf
- Asian Development Bank to Punjab National Bank (USD 500 million). See loan product
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 below
- Checking module connection integrity
- Checking junction / string combiner boxes
- Inspectingmechanical 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