Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 1
FIRST GREEN CONSULTING
DISCUSSION PAPER
SOLAR ROOFTOP SYSTEMS: ALTERNATIVE TO SUPPORT
GROWING ENERGY NEED
Author:
DR. SANJAY VASHISHTHA (DIRECTOR, FIRSTGREEN CONSULTING PVT. LTD)
Co-Author:
SAACHI SINGLA (PGPM ENERGY CANDIDATE, GREAT LAKES IEMR)
First Green Consulting Private Limited
U-28 A/3, DLF Phase 3,
Gurgaon, Haryana- 122002. India
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TABLE OF CONTENTS
I. INTRODUCTION.............................................................................................04
II. ROOFTOP SOLAR SYSTEMS.............................................................................05
1. Initiatives for rooftop systems under JNNSM...................................................................05
2. Components of rooftop systems....................................................................................06
3. Installing rooftop system over building...........................................................................07
4. Assessment of roof for Solar PV.....................................................................................07
5. Assessment of generation.............................................................................................08
6. Assessment of cost of rooftop Solar PV..........................................................................08
III. FINANCIAL ASSESSMENT................................................................................08
1. Financing of Rooftop Solar PV Systems...........................................................................08
2. Economics of Rooftop Systems......................................................................................09
IV. TECHNICAL ASSESSMENT...............................................................................10
1. Grid Connectivity.........................................................................................................10
2. Net Metering...............................................................................................................11
3. Power Purchase Agreement..........................................................................................11
4. Feasibility Check for rooftop PV system..........................................................................11
V. POLICY INCENTIVES AND SUBSIDIES............................................................12
VI. SOLAR ROOFTOP LEASING AGREEMENT..........................................................15
VII. FUTURE OUTLOOK..........................................................................................15
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LIST OF FIGURES
Figure 1: Solar Energy Potential in India............................................................................04
Figure 2: Schematic diagram of Solar Rooftop System.........................................................07
Figure 3: Cost of Generation v/s Interest rates & Average Tariff v/s Variation in load from DG &
HVPNL..........................................................................................................................10
Figure 4: Cost of Generation v/s Subsidy...........................................................................10
Figure 5: Cost of Generation v/s Capex.............................................................................10
Figure 6: Feed-in metering and Net metering.....................................................................14
LIST OF TABLES
Table 1: JNNSM Targets..................................................................................................06
Table 2: Proposed Capacity Allocation under JNNSM............................................................12
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I. INTRODUCTION
The current installed capacity of India stands at around 207 GW1. India has been richly endowed with
renewable resources. The existing installed capacity of renewable power in India is around 25.82 GW, which
accounts for about 12% of the total installed capacity. Harnessing of non-polluting renewable energy
resources to control green house gases is receiving impetus from the Government of India. As a part of
National Action Plan on Climate Change, Government of India launched Jawaharlal Nehru National Solar
Mission (JNNSM) in 2009 to promote the development and use of solar energy for power generation and
other uses with the ultimate objective of making solar energy competitive with fossil-based energy options.
The solar photovoltaic device systems for power generation had been deployed in various parts of the
country for electrification where the grid connectivity is either not feasible or not cost effective as also
sometimes in conjunction with diesel based generating stations in isolated places and communication
transmitters at remote locations. With the downward trend in the cost of solar energy and appreciation for
the need of development of solar power, solar power projects have recently been implemented. A significant
part of the large potential of the solar energy in the country could be developed by promoting grid-
connected solar photovoltaic power systems of varying sizes as per the need and affordability coupled with
ensuring adequate return on investment.
While India receives solar radiation of 5 to 7 kWh/m2 for 300 to 330 days in a year, power generation
potential using solar PV technology is estimated to be around 20MW/sq. km and using solar thermal
generation is estimated to be around 35MW/sq. km.
Figure 1: Solar Energy Potential in India
1 http://www.cea.nic.in/reports/monthly/executive_rep/sep12/8.pdf as on 30.09.12
2 http://www.mnre.gov.in/mission-and-vision-2/achievements/ as on 31.08.2012
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Considering 300 average clear sunny days and daily average global solar radiation to be around 5.8 kWh/sq
m/day, the capacity utilization factors for various Solar PV based is expected between 15-25% based on
SPV (thin film or crystalline) and upto 35% based on concentrated PV.
The input for the project is the Solar Radiation which is very conducive to setup a Solar PV plant across
country. The economical land is feasible, as India has sufficient deserted space without residential /
agricultural or commercial use and has plenty of Roof Tops. The technology is within reach and most
technology providers have started focusing India, the knowledge base is developed with execution of >1000
MW capacity addition in last 2 years. There is an acute power shortage thus there is strong need for the
user to pay for energy generated. All the elements are available in India, except the big challenge of making
financial sense from the investments.
II. ROOFTOP SOLAR SYSTEMS
While there is a considerable interest in the utility scale grid connected solar power plants, roof top systems
are equally getting attention and the country has about 43 MW of roof top systems connected to the grid.
Rooftop PV systems are much more attractive due to the fact that these systems have potential to reduce
transmission and distribution losses and further reduce additional burden of laying the T&D infrastructure.
Connecting roof top solar PV systems to the grid is a great challenge, specially the rooftop systems which
are in kW capacity; the utilities face tremendous challenge in terms of handling the unstable sources of
electricity at distributed level. While the PV system costs have come down considerably, roof top systems
provide altogether a new market to the urban households who already have an inverter and battery storage
systems as back up source in the event of grid unavailability.
In India, the application of solar PV has a particular significance, given the condition of its transmission and
distribution infrastructure – high losses, poor power quality and frequent load shedding. Most buildings,
public, private and commercial (for example, malls, hotels, hospitals and nursing homes), have diesel
generators for back-up in case of load shedding by the utility. Given environmental considerations, the use
of diesel should be minimised. There is abundant opportunity to use rooftop or building-mounted solar PV
systems to generate electricity and thereby reduce the consumption of diesel. Due to the intermittent supply
of solar power and grid outages, diesel–solar PV hybrid models could be potential solutions. Generous
subsidies have been offered by the Government (both Central and State). Despite this, widespread
installation of solar PV systems to generate electricity on urban rooftops does not seem like a reality that
will take the shape in the near future.
1. Initiatives for rooftop systems under JNNSM
Government of India launched its National Solar Mission in January 2010 with a targeted installation of
about 20 GW of solar electricity by 2022 under the Jawaharlal Nehru National Solar Mission (JNNSM).
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Table 1: JNNSM Targets:
Application
Segment
Target for Phase-1
(2010-13)
Target for Phase-2
(2013-17)
Target for Phase-3
(2017-22)
Utility Grid Power 1,000-2000 MW 4000-10,000 MW 20,000 MW
Off-grid
Applications
200 MW 1000 MW 2000 MW
The first phase has observed a remarkable attention and achieved installations of the order of 950 MW of
solar electricity in the country. The JNNSM also supports small-scale-grid connected systems under the
Rooftop PV and Small Scale Solar Power Generation Programme (RPSSGP). Under this program of JNNSM by
Sept, 2012, 87.803 MW of solar photovoltaic (PV) plants have been commissioned out of 98.05 MW holding
Power Purchase Agreements (PPAs) under the nation’s Rooftop Solar PV and Small scale Solar Power
Generation Program (RPSSGP) program in phase-1, batch-1 (See annexure1).
2. Components of Rooftop System
A typical rooftop system generally comprises of the following equipments:
i. SPV Power Source
ii. Inverter
iii. Grid Charger (only for system with batteries)
iv. Charge Controller (only for system with batteries)
v. Batteries (Optional)
vi. Mounting Structure
vii. AC and DC Cables
viii. Earthing equipment /material
ix. Junction Boxes or combiners
x. Instruments and protection equipments
The solar modules are connected to an inverter to yield 240V AC at medium power levels (2-10kW). This
system is connected to AC power lines (i.e., connected to the grid) as shown in Figure 2. The customer sells
power to the utility during the day and buys power from the power company during the night. Some of the
rooftop systems have inbuilt inverters, also known as micro inverters which convert the electricity generated
by module directly in to AC electricity at the module output itself. The use of micro inverter system greatly
reduces installation labour costs, improves safety, and maximizes the solar energy harvest.
It is possible to integrate the solar module with your existing home inverter system and can reduce the
capital cost significantly. The solar panels are connected to the existing home inverter-battery system
3 http://mnre.gov.in/file-manager/UserFiles/commissioning_status_spv_batch1_phase1.pdf
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through a hybrid charge controller and can provide relief to the households for additional charging option
apart from normal grid charging of the storage batteries. In the event of non requirement of solar electricity
at the household, this surplus electricity can be fed back to the grid as well. The home owner has to install
this converter along with the existing inverter which also acts as a battery charge controller and connects
the AC mains & load output control system all in one.
Recently NREL has developed a new breed of solar cells which are organic cells, which have been used for
window panes to convert the sunlight in to electricity through the window panes termed as Solar Window.
The research team has developed a conductive wiring grid that is practically invisible, which provides for
more efficient energy harvesting without interfering with the see-through quality of the panel.
Figure 2: Schematic diagram of Solar Rooftop System
3. Installing rooftop system on your building
Installing a solar rooftop solar PV system requires a basic understanding of technical, economic and
regulatory aspects to take a call for the viability of these systems. Installing a rooftop solar PV system is
different than installing a typical solar water heating system as it has many sub systems such as inverter
selection and net metering etc. PV systems have limitations that they produce power intermittently because
they work only when the sun is shining. It is difficult for PV systems to furnish all the power you need, and
are typically used in conjunction with utility-supplied electricity.
4. Assessment of the Roof for Solar PV
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The best orientation for a rooftop solar PV system is on a south-facing roof; hence it is important that the
roof has a south facing option available to install solar PV system. A flat horizontal roof is also eligible for
solar PV facing clear sky and having shadow free area. The amount of roof space needed for Rooftop Solar
PV systems is determined on the basis of selection of PV generating capacity. Typically a rooftop system
requires about 100 ft2 area to house a 1 kW power.
5. Assessment of generation
PV systems produce the most electricity during October to March when the sun is shining. Energy production
will vary, of course, depending on geography and climate. A typical 1 kW roof top PV system will produce
about 1600-2000 kWh in a year depending on the location. If we consider a typical household demand of
12000 Units a year, then a typical 5 kW rooftop system will meet about 60-70% of the annual household
electricity demand.
6. Assessment of cost of rooftop solar PV
The electricity generated from rooftop systems are still more expensive than conventional grid electricity,
however it all depends on how much is the opportunity cost of displaced electricity. If the displaced
electricity is a combination of grid and DG based electricity, in that case the cost of displaced electricity is
about 9 Rs/unit which makes solar PV system much more attractive to the roof top installer. Although the
utility grade Solar PV is now costing about 80-90 Rs/Wp, the rooftop PV systems will cost about 120 Rs/Wp
due to economy of scale. Considering a cost of 120 Rs/Wp for a typical roof top system a 10 kW roof top
system will cost about 12 Lac. The building owner is also eligible for 30% capital subsidy (3.6 Lac) and
accelerated depreciation upto 80%. Hence the building owner has to spend about 40% of the total cost of
the systems, which makes PV attractive in terms of low capital cost.
III. FINANCIAL ASSESSMENT
1. Financing of Rooftop Solar PV Systems
Government of India has launched a low interest based financing scheme for roof top systems and it is
available from many commercial banks and also through NABARD. The interest rate charged for the roof top
systems is of the order of 5%.
All Commercial Banks (including private commercial banks) and Regional
Rural Banks are eligible to avail refinance facilities from NABARD to refinance the rooftop solar PV systems.
Funds towards meeting the subsidy and refinance requirements under the scheme are provided to NABARD
by IREDA. The rooftop projects eligible for funding support under the Scheme will need prior approval from
the Project Approval Committee of MNRE. MNRE would provide financial support through a combination of
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30%4 capital subsidy and/ or 5% interest bearing loans. For the year 2011-12, the benchmark price for
photo voltaic with battery back-up is considered as 300 per Watt Peak (Wp). In respect of the systems
which do not use storage battery such as water pumping systems, the installed PV system cost would be
considered subject to a cap of ` 210 per Wp. Capital subsidy of 90% of the benchmark cost, would be
available for special category states, viz. NE, J&K, Himachal Pradesh, Sikkim and Uttarakhand.
2. Economics of Rooftop Systems
PV power generation has long been considered as a costly technology, due to higher installation cost, use of
rare earth material like Silicon, and low conversion efficiency, etc. Due to higher upfront cost, the roof top
PV installations are globally driven through subsidies in case of off grid systems and Feed in Tariffs (FITs) in
case of grid connected rooftop PV systems. In recent years, the rapid cost reductions in PV module prices
have led PV as one of the alternative technology which is at par with some of the costly conventional power
sources.
The economics of PV plants is generally assessed in terms of cost per watt peak (Rs/Wp) or in terms of
levellised cost of energy (LCOE) and represented in terms of Rs/kWh. While the manufacturing community
assess the cost in Rs/Wp, the investor community assess the economics in terms of LCOE. Since 2004,
regardless of module prices, system prices have fallen steadily as installers achieved lower installation and
maintenance costs. The LCOE for rooftop PV systems has declined by nearly 50% in last three years. Most
important determining factors of the levellised cost as being capital costs, capacity factor, cost of equity and
cost of debt.
Consider a typical 100 kW Solar Rooftop PV Plant compared to the general supply of 70% from grid and
peak 30% from DG sets (Annexure-2). Calculating the return on the savings from the above system i.e.
switching to rooftop rather than following the conventional systems, gives a return of 10% . Working out the
total cost from the rooftop systems, based on Rs. 120/Wp, the Capital Cost of 100kW Rooftop PV plant is
Rs.1.3 Mn with the Capacity Utilization Factor (CUF) of 21%. The equity investment needed is Rs. 1.68 Mn
and the amount funded from Bank loan works out to be Rs. 6.72 Mn. Figure-3 shows that the cost of power
generated by PV exhibit a particularly high sensitivity to the interest variations, followed by variations in
average tariff by changing the %age of power generated from DG and Grid. Figure 4 and 5 also gives the
variation of cost of power generated with the inclusion of subsidy and with the variation of capex
respectively.
Figure 3: Cost of Generation v/s Interest Rates & Average Tariff v/s variation in load from DG and HVPNL
4 http://mnre.gov.in/file-manager/UserFiles/jnnsm_g170610.pdf
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Figure 4: Cost of Generation v/s Subsidy
Figure 5: Cost of Generation v/s Capital Expenditure
3.00
5.00
7.00
9.00
11.00
13.00
1 2 3 4 5 6 7 8 9 10
Co
st
of
Gen
erati
on
(R
s./
kW
h)
Cost of Generation
Interest 12% Interest 10% Interest 8%
Interest 6% Average Tariff (70:30) Average tariff (80:20)
Average Tariff (60:40)
3.0
4.0
5.0
6.0
7.0
8.0
9.0
1 2 3 4 5 6 7 8 9 10
Co
st
of
Gen
erati
on
(R
s./
kW
h)
Cost Of Generation
Without Subsidy With Subsidy
3.00
4.00
5.00
6.00
7.00
8.00
1 2 3 4 5 6 7 8 9 10
Co
st
of
gen
erati
on
(R
s./
kW
h)
Cost of Generation
Capex: Rs.100/watt Capex:Rs.110/watt Capex:Rs.120/watt
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IV. TECHNICAL ASSESSMENT
1. Grid Connectivity
CERC lays down the guidelines for Rooftop Solar PV and other Small Solar Power Projects to be connected to
the distribution network at voltage levels below 33 kV to be considered eligible for generic tariff
determination.
2. Net-Metering
Net metering allows electricity meter to spin forward when electricity flows from the grid into your building,
and backward when your system produces surplus electricity that is not immediately used. Your excess
electricity is “banked” on the utility grid. Metering helps to measure the solar gross generation, consumer
load consumption, export and import to and from the Grid apart from measurement of AC system voltages
and currents, frequency etc. As per the guidelines of CERC, the metering arrangement requires to
accommodate DG sets and/or battery inverter etc. as per the need of solar developer without affecting the
sealing and security of complete metering system apart from cabling and switchgear from solar panel to
solar meter.
3. Power Purchase Agreement
The recent cost reduction in solar PV has motivated many building owners to use on-site or off site
photovoltaic (PV) generation to hedge against volatile electric utility bills. In case of onsite generation the
building owner has an option of installing himself and owns the PV system. Another option to the building
owner is to do a PPA with the third party for long terms and avoid the high capital investments. Typically in
case of rooftop PV systems, the third party signs a PPA with the building owner and sell the solar electricity
as a part of onsite generation to displace his costly DG based power generation. As long as this system is
completely off grid, there is no problem in terms of meeting the regulatory compliances, however in case of
grid interactive systems, if the solar PV installer at a building installs the PV plant, and go for net metering,
there are no guidelines from Government of India for net metering of solar electricity. Also it is not clear
that the PPA signed by the third party who sell its solar electricity to the building owner as well as to the
grid in the event of non-captive requirement, is he legally allowed to sell the electricity to both parties. The
third party sale can be done under the group captive mode where the buyer should have stake in a Solar PV
at least 26% and should have at least 51% of solar electricity. Rest of the electricity can be sold to the grid.
A growing number of third-party solar power providers are looking to rent roof surfaces from the home
owners and install PV systems and sell the power generated to the home owner/local utility through the
different available scheme of solar rooftop policies of government of India. Even commercial building owners
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can also lease their rooftop on rent to the solar PV developers and can do a long term PPA to use the
electricity generated through the PV system.
4. Feasibility Check For Rooftop PV System
Before performing a detailed site survey, a client prefers to do the feasibility check by considering the
following parameters:
Shadow Test: To collect the maximum sunlight during the day, the panels should be faced to the South as
much as possible. The roof must be checked from the shadow of the trees and of the neighbouring roofs and
walls. In case there is some shadow on the roof, a detailed analysis of time and direction of sunlight needs
to be evaluated to estimate the energy received by the rooftop.
Rooftop Type: The load carrying capacity of the roof should be checked. Solar panels with structure typically
weigh 15 kg per sq. meter. This weight varies with technology and type of structure.
Sizing of Solar system: Size of the solar system depends on the available rooftop area for installation of
panels. This can be calculated by dividing the entire roof area by each panel area and multiplying it by the
panel’s rated output. For estimate purposes, 70% of rooftop area can be used for panel’s installation.
Size of the solar system = Panel’s rated output* (rooftop area/ each panel area)*70%
System Output: The panel output and hence the system output is defined by the Capacity Utilization Factor
which defines the panel efficiency and the solar radiation incident on the panel. Typically, for India the CUF
for solar plants is estimated at 19%.
Number of units generated = Installed capacity* 365*24* CUF
V. POLICY INCENTIVES AND SUBSIDIES
MNRE launched a program referred to as “ Rooftop PV and Small Solar Power Generation Programme” for
the small solar power plants connected to distribution network at voltage levels below 33 kV and envisaged
under Phase I of the JNNSM . The programme envisages developing about 100 MW of solar capacity.
Table 2: Proposed Capacity Allocation under JNNSM
S.No. Project Category Proposed Capacity Limit
1. Projects connected at HT Level with installed
capacity of 100 kW to 2 MW
90 MW
2. Projects connected at LT Level with installed
capacity of less than 100 kW
10 MW
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Various states have also taken individual rooftop initiatives which are summarised in annexure 3.
MNRE offers 3 types of financial incentives for the solar rooftop systems:
Capital Subsidy: MNRE provides 30% capital subsidy on capital expenditure for rooftop solar PV system.
For commercial and non-commercial entities in grid connected area, subsidy can be granted to a plant size
upto 100kW. However, entities setting up solar plant for rural electrification can claim a subsidy for upto 250
kW plant size.
Interest Subsidy: The government provides soft loans at 5% per annum on 50% of the capex amount for
5 years tenure for solar projects by both commercial and non-commercial entities. Commercial entities can
claim any of interest or capital subsidy but the non-commercial entities can claim both subsidies
simultaneously.
Accelerated Depreciation: For solar system, a company can claim 80% depreciation in the first year itself
leading to savings on income tax on overall profit. This benefit can be claimed by both commercial and non-
commercial entities. The procedure for the availing the financial incentive includes the following process:
To claim the financial incentive, an application needs to be written to MNRE in the prescribed application
form for project approval. A commercial entity seeking to avail incentive needs to specify its preference for
capital or interest subsidy. Once approved, in case of interest subsidy, the MNRE forwards the application to
the commercial bank for the soft loan. In case of capital subsidy option, MNRE provides subsidy money in 3
phases: start of project, mid-way through the project and after the successful completion of the project.
Apart from MNRE, the entities can avail of commercial loans from organizations such as SIDBI at 15%
interest rate typically for 7 years with 1 year moratorium period.
SOLAR ROOFTOP POWER IN GUJARAT
Currently Feed-in-Tariff is only available in Gujarat .Similar solar feed-in-tariff policies are under process of
being released in Delhi and other states. It is a means of promoting solar power and will serve to meet peak
demand in the cities of India.
Kilowatt –scale photovoltaic power plants, which are mounted on rooftops and directly feed electricity into
the grid, are typically connected to the grid on one of the following philosophies:
1. Feed-in metering (two-meter) philosophy
The two-metering interconnection scheme is applicable where a separate feed-in-tariff is allowed for feeding
of solar electricity into the grid, and hence will be applicable in Gujarat. Energy is easily accounted for in this
case through a dedicated feed-in-meter. Such schemes are applicable in several European countries
including Germany.
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2. Net metering philosophy
Net metering is applicable where the conventional electricity and solar electricity are traded at the same
tariff. As the cost of solar electricity is higher compared to the conventional electricity, such a net- metering
scheme requires has to be supported with additional subsidies to the developer. Such schemes are quite
popular in countries including USA and Japan.
Figure 6: Feed-in Metering and Net Metering
Gujarat has also recently announced to install 5 more Rooftop Solar Projects of 25 MW capacity. The
five projects are divided into three packages. The first is for putting up 5 MW plant each in Vadodara and
Mehsana. The second is for 6.5 MW project in Rajkot and 3.5 MW in Bhavnagar. The third is for 5 MW plant
at Surat. These projects would be grid-connected where a developer would rent a roof, build the plant and
sell power to the state electricity distribution company, GUVNL. The discoms would purchase power for 25
years from these developers.
Kerala Rooftop Policy
Kerala State Nodal Agency, ANERT, recently launched 10,000 Solar Rooftop Power Plants Programme 2012-
13 . The programme envisaged the installing of 1kW*10000 Solar Roof-top Power Plants during the year
2012-13 with a total of 10MW capacity. One system with 1kWp is allowed to each individual beneficiary,
with Central and State financial support. The minimum requirement for installation should be 15sq meter of
shade-free area and appropriate space for putting the batteries and inverters. The system would be in the
off-grid mode generating approx. 4 units per 1 kWp system per day. This electricity is to be used for internal
combustion. Central financial assistance from state would be minimum of either 30% cost of the project or
Rs. 81,000/ per system. Apart from the Central subsidy, the state subsidy of Rs. 39000/per system is also
available for the approximate cost of the plant of Rs. 2.5 lakh.
Feed-in metering interconnection scheme Net metering interconnection scheme
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VI. SOLAR ROOFTOP LEASING AGREEMENT
Most rooftop solar developers require an option to lease the rooftop. The option will permit the
operator to have access to inspect and test the rooftop and do such other investigations as it
deems necessary to satisfy itself that the location is suitable for a solar PV array and that the
building owner is in a position to grant a lease to it. The option will be open for exercise by the
operator for a period sufficient to enable the operator to conduct such inspections and
investigations and to apply for and obtain a Feed in Tariff (“FIT”) program approval or enter into
a power purchase agreement (“PPA”) with the local electrical utility. The option agreement will
provide that if the developer exercises its option, the parties will enter into a lease of the rooftop
area on the terms set out in the option agreement.
Generally the rooftop lease is signed for 20 years (to match the term of the FIT or PPA) and the
tenant/installer will most likely ask for the exclusive option to renew the lease. Renewal rights
are potentially important, as it is anticipated that the productive life of the solar photovoltaic
(“PV”) array equipment may be substantially longer than 20 years. Rent can be structured in
several ways. Usually, it will be a fixed, all-inclusive “gross” rent, but it may be calculated based
on the size of the roof area or the portion of the rooftop utilized, the wattage produced by the
facility, a percentage of the revenues received by the tenant, or on some other basis. In addition,
the lease may provide for the tenant to pay for its electricity consumption and for any realty
taxes associated with the solar PV array.
VII. FUTURE OUTLOOK
To enhance the energy capture from each solar panel, Sun Power came up with Sun Power T10 Solar Roof
Tile to tilt a 10-degree angle. These non-penetrating solar roof tiles interlock for security and rapid
installation. The durable, light-weight materials and the patented design resists high winds and corrosion.
Uniquely flexible, the Sun Power T10 Solar Roof Tile adapts to the size and requirements of virtually any flat
rooftop. For facilities trying to achieve the maximum power density from their solar solution, the Sun Power
T5 Solar Roof Tile may be a better option. However, for facilities where space constraints are not a primary
consideration, the T10 is the ideal solution as it will increase the total energy production from each solar
panel.
On the whole, if we consider 30% captive power generation in commercial buildings, the average cost of
power to the consumers is about 8.5 Rs/kWh, this is the point where the roof top systems make commercial
sense. But do they really have roof top space to accommodate the solar power at their roof. The vertical
high rise glass buildings which are energy guzzlers hardly have any rooftop space for solar power systems.
The buildings in tier 2 and tier 3 cities have much more horizontal spread which makes good case for
accommodating the rooftop systems. Although the glass facade in case of high rise buildings can be of solar
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PV as building integrated PV systems, however they extract very less energy due to the limitation of solar
energy falling in a perpendicular fashion on them. Our limitation is that we design buildings and then think
of solar to integrate with the existing design.
In-order to achieve its solar portfolio obligations New Delhi Power Limited has already proposed a rooftop PV
programme with a target of 50 MW for 10,000 customers in the first phase of JNNSM. The experiences in
Germany and California on roof top systems show a great relief to the distribution losses. Adopting the
rooftop system in India as well is likely to provide a great relief to the Indian utilities as well in terms of
reduced distribution losses. While the cost of utility scale projects have already come down to about Rs. 8
cr./MW, it is important to develop market based mechanisms through which the cost of roof top systems can
be brought down. Current rooftop systems cost almost Rs. 12-13 Cr./MW, due to the higher labour,
transaction and implementation costs. The economics of rooftop systems makes sense only to the
consumers who have high dependency on the captive DG sets, which they use in the event of grid failure. It
is important to have more generic guidelines for grid integration, connectivity, net metering, etc for large
scale deployment of roof top systems.
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 17
FIRST GREEN CONSULTING
ANNEXURES
Annexure 1: Commissioning Status of Roof Top Solar PV Projects under Batch-I, phase-I of
JNNSM under RPPSGP Scheme
S.No. Name of project commissioned State Solar PV capacity
commissioned (MW)
1 Sri Power Generation (India) Private Limited Andhra
Pradesh
1.0
2 Amrit Jal Ventures Pvt. Ltd. Andhra
Pradesh
1.0
3 Andhra Pradesh Power Generation
Corporation Ltd.
Andhra
Pradesh
1.0
4 Ramakrishna Industries Andhra
Pradesh
1.0
5 Singhal Forestry Private Limited Chhattisgarh 2.0
6 Chhattisgarh Investments Ltd. Chhattisgarh 2.0
7 Chandraleela Power Energy Private Limited Haryana 0.8
8 Zamil New Delhi Infrastructure Private
Limited
Haryana 1.0
9 SDS Solar Private Limited Haryana 1.0
10 Sukhbir Solar Energy Private Limited Haryana 1.0
11 C&S Electric Ltd. Haryana 1.0
12 Dr.Babasaheb Ambedkar Sahakari Sakhar
Karkhana Ltd.
Maharashtra 1.0
13 Sepset Constructions Limited Maharashtra 2.0
14 Citra Real Estate Limited Maharashtra 2.0
15 MGM Minerals Ltd. Orissa 1.0
16 Raajratna Energy Holdings Private Limited Orissa 1.0
17 S N Mohanty Orissa 1.0
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 18
FIRST GREEN CONSULTING
18 Molisati Vinimay Pvt. Ltd. Orissa 1.0
19 Soma Enterprise Limited Punjab 1.0
20 AEW Infratech Pvt. Ltd. Rajasthan 1.0
21 Asian Aero- Edu Aviation Private Limited Rajasthan 1.0
22 Basant Enterprises Rajasthan 1.0
23 Zamil New Delhi Infrastructure Private
Limited
Rajasthan 1.0
24 Navbharat Buildcon Pvt. Ltd. Rajasthan 1.0
25 Lanco Solar Private Ltd. Rajasthan 1.0
26 B&G Solar Private Limited Tamil Nadu 1.0
27 RL Clean Power Pvt. Ltd. Tamil Nadu 1.0
28 Great Shine Holdings Pvt. Ltd. Tamil Nadu 1.0
29 RV Akash Ganga Infrastructure Ltd. Uttarakhand 2.0
30 Technical Associates Ltd. Uttar
Pradesh
2.0
31 Kijalk Infrastructure Pvt. Ltd. Jharkhand 2.0
32 Metro Frozen Fruits & Vegetables Ltd Uttrakhand 1.0
33 Andromeda Energy Tech. Pvt. Ltd. AP 0.75
34 Vivek Pharmachem Rajasthan 1.0
35 Ecoenergy Inc Punjab 1.0
36 Sovox Renewables Private Limited Punjab 1.0
37 G S Atwal & Co.(Engineers) Pvt. Ltd. Punjab 1.5
38 Amson Power Private Ltd. Tamil Nadu 1.0
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 19
FIRST GREEN CONSULTING
39 SunEdison Energy India Private Ltd. Rajasthan 1.0
40 Kishore Electro Infra Pvt.Ltd. Andhra
Pradesh
1.0
41 Harrisons Power Pvt Ltd. Tamil Nadu 1.0
42 Gajanan Finacial Services Pvt. Ltd. Andhra
Pradesh
1.0
43 Dhruv Milikose Pvt. Ltd. Uttar Pradesh 1.0
44 Photon Energy Systems Limited Andhra
Pradesh
1.0
45 Dante Energy Pvt. Ltd. Uttar Pradesh 2.0
46 Tayal & Co. Haryana 1.0
47 VKG Energy Pvt. Ltd. Haryana 1.0
48 H.R. Minerals And Alloys Pvt. Ltd. Haryana 1.0
49 Cartill Energy Pvt. Ltd. Punjab 1.5
50 Abacus Holdings Pvt. Ltd. Orissa 1.0
51 Bhavani Engineering Andhra
Pradesh
1.0
52 PCS Premier Energy Pvt. Ltd. Jharkhand 2.0
53 Jay Ace Technologies Ltd. Uttarakhand 2.0
54 Sovox Renewables Private Limited Rajasthan 1.0
55 Andhra Pradesh Industrial Infrastructure
Corporation Limited
Andhra
Pradesh
1.0
56 New Era Enviro Ventures Private Limited Jharkhand 2.0
57 Premier Solar Systems Pvt Ltd. Jharkhand 2.0
58 Conflux Infratech Private Limited Rajasthan 1.0
59 Enertech Engineering Private Limited Jharkhand 2.0
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 20
FIRST GREEN CONSULTING
60 Pantime Finance Company Private Limited Odisha 1.0
61 Shri Mahavir Ferro Alloys Private Limited Odisha 1.0
62 KVR Constructions Jharkhand 2.0
63 AKR Constructions Ltd. Jharkhand 2.0
64 Saimeg Infrastructure Pvt. Ltd. Jharkhand 2.0
65 Priapus Infrastructure Ltd. Uttar Pradesh 2.0
66 Adora Energy Private Limited Madhya Pradesh 2.0
67 JSR Developers PVT. Ltd. Madhya Pradesh 1.25
68 Shiv-Vani Energy Limited Madhya Pradesh 2
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 21
FIRST GREEN CONSULTING
Annexure- 2 Typical 100 kW Rooftop PV Plant
Financial and Tariff Assumptions
Assumptions supporting Financial Projections Input Value Units
Project Capacity 100 kW
Cost/Watt 120 Rs.
Total Project Cost 1.2 Crores
Subsidy 30%
Actual Investment 0.84 Crores
Debt 80%
Equity 20%
Debt Amount 0.67 Crores
Equity Amount 0.17 Crores
Interest rate 12%
Loan Tenure 10 Years
Return on Equity 12%
Plant Load Factor 19%
Tariff Increment 3%
O&M Expenses 3% of project cost
Escalation in O&M 5%
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 22
FIRST GREEN CONSULTING
Cash Flow and Returns Calculations
Years 0 1 2 3 4 5 6 7 8
Power generation 166440 164776 163128 161497 159882 158283 156700 155133
30% Load on DG 49932 49433 48938 48449 47964 47485 47010 46540
70% Load on HVPNL 116508 115343 114189 113048 111917 110798 109690 108593
5% Cost of DG supply (5% sc) 15 15.75 16.54 17.36 18.23 19.14 20.10 21.11
5% Cost of HVPN Supply 6 6.30 6.62 6.95 7.29 7.66 8.04 8.44
Average Tariff 8.70 9.14 9.59 10.07 10.57 11.10 11.66 12.24
Energy charges (INR) 1448028 1505225 1564681 1626486 1690733 1757517 1826938 1899103
Finance cost 1,008,000.0
962,048.0
910,581.7
852,939.5
788,380.2
716,073.8
635,090.6
544,389.4
12% Return on equity 201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
12% Debt Interest portion (10 year loan)
806,400.0
760,448.0
708,981.7
651,339.5
586,780.2
514,473.8
433,490.6
342,789.4
2% Operating cost 240,000 244800 249696 254689.92 259784 264979 270279 275685
2% Escalation in Operating Cost
` Total costs 1,248,000.0
1,206,848.0 1,167,777
1,107,629.4
1,048,163.9
981,053.2
905,369.6
820,074.0
Cash flow - 8,400,000 200,028.0
298,377.1
404,403.8
518,857.0
642,568.7
776,463.4
921,568.9
1,079,028.6
IRR 10%
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 23
FIRST GREEN CONSULTING
9 10 11 12 13 14 15 16 17 18 19 20
153582 152046 150525 149020 147530 146055 144594 143148 141717 140299 138896 137508
46074 45614 45158 44706 44259 43816 43378 42944 42515 42090 41669 41252
107507 106432 105368 104314 103271 102238 101216 100204 99202 98210 97228 96255
22.16 23.27 24.43 25.66 26.94 28.28 29.70 31.18 32.74 34.38 36.10 37.90
8.86 9.31 9.77 10.26 10.78 11.31 11.88 12.47 13.10 13.75 14.44 15.16
12.85 13.50 14.17 14.88 15.62 16.41 17.23 18.09 18.99 19.94 20.94 21.98
1974117 2052095 2133152 2217412 2305000 2396047 2490691 2589073 2691342 2797650 2908157 3023029
442,804.1 329,028.6
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0 201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
201,600.0
241,204.1 127,428.6
281198 286822 292559 298410 304378 310466 316675 323008 329469 336058 342779 349635
724,002.4 615,850.8
494,158.7
500,009.8
505,978.0
512,065.6
518,274.9
524,608.4
531,068.6
537,657.9
544,379.1
551,234.7
1,250,114.7 1,436,243.9
1,638,993.8
1,717,402.1
1,799,021.7
1,883,981.7
1,972,416.2
2,064,465.0
2,160,273.2
2,259,991.9
2,363,777.9
2,471,794.5
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 24
FIRST GREEN CONSULTING
Cost of generation 7.50 7.32 7.11 6.86 6.56 6.20 5.78 5.29 4.71 4.05
1 2 3 4 5 6 7 8 9 10
Yearly Installment 1189334 1189334 1189334 1189334 1189334 1189334 1189334 1189334 1189334 1189334
Interest 806,400
760,448
708,982
651,339
586,780
514,474
433,491
342,789
241,204
127,429
Principal Repayed 382,934
428,886
480,352
537,994
602,553
674,860
755,843
846,544
948,129
1,061,905
Balance 6,337,066
5,908,181
5,427,829
4,889,835
4,287,281
3,612,422
2,856,579
2,010,034
1,061,905
0
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 25
FIRST GREEN CONSULTING
Annexure-3
Rooftop Subsidy scheme
With the success of JNNSM policy for the projects of grid connected MW capacity and continuous
declining movement of panel cost will make the rooftop systems economically more viable option. The
Government’s policy will act as a catalyst for the same. Here the First Green is providing you a gist of
the policy for off grid Roof top system (programme on “Off-grid and Decentralized Solar Applications”,
8th June 2012)
• Government of India (MNRE) provides 30% of capital subsidy on the roof top systems (off grid).
Based on the benchmark cost for solar photovoltaic panels (revised on 01/04/11 by MNRE) the
available subsidy is of Rs 81/Wp with battery and Rs 57/Wp without battery storage system.
• Promoters’ equity contribution should be at least 20% of the project cost
• Rest of the amount can also be financed by MNRE by a soft loan @5% will be available.
• 80% accelerated depreciation benefit is available as per Section 32 of Income Tax Act.
• Rs 100/Wp for SPV modules used subject to a maximum of 40% of the cost of the system to non-
profit making organizations only
• Support will be available for systems capacity varying between 25 to 100kW.
• Proposals in prescribed format will be considered on first-cum-first basis through SNAS by MNRE
• Capital subsidy would be released to the banks upfront, on receipt of sanction of loan by the bank
to the borrower.
• The loan amount is repayable in monthly instalments within 5 years.
Boundary Conditions
The policy also defines maximum boundary conditions to avail subsidy and incentives for the projects
under this programme on “Off-grid and Decentralized Solar Applications”
Individuals: Capital Subsidy & Soft Loan
• Pumps for irrigation and community drinking water – up to 5 kWp
• All except above – up to 1 kWp
Non Commercial Entities: Capital Subsidy & Soft Loan
• Mini grids for rural electrification – up to 250 kWp
• All except above – up to 100 kWp
Industrial / Commercial Entities: Capital Subsidy or Soft Loan
• Mini grids for rural electrification – up to 250 kWp
• All except above – up to 100 kWp
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 26
FIRST GREEN CONSULTING
Gujarat Solar Rooftop Policy
Gujarat Government, after the successful installation of about 605 MW of Solar Power plant in
Charanka in Patan district, now plans to introduce Rooftop Solar Power Plant Policy. Gandhinagar, as
of now , already has about 1.39 MW of solar rooftop systems covering about 2 acres of roof-top area.
The Gujarat State , recently, also envisaged a 5 MW rooftop programme on the PPP model in the
capital which is now extended to about 5 more cities and towns. The entire solar power project is
expected to produce about 30 lakh units of clean energy daily, which is capable of electrifying about
10 lakh households and save about 10 lakh tonnes of CO2 emissions. The advancement and growth
in the technology has reduced the cost of solar plants significantly from about Rs.15 to Rs. 8.5 per
unit in the past years, thus making it comparable with the gas-based power.
Rooftop policy of Haryana
The Haryana Renewable Energy Development Agency (HAREDA) recently launched the Solar Rooftop
Scheme to motivate commercial and industrial establishments like hotels, hospitals and housing
complexes to replace DG sets installed for captive requirement during load shedding. Under this
scheme, HAREDA approved 2 standalone solar PV projects of 100 kW each in Gurgaon to demonstrate
applications of solar PV for industry power back-up. The State Government has agreed to offer
financial assistance of Rs 75 lakh for each project.
Solar City Program of MNRE
In February 2009, MNRE announced a scheme on ‘Development of Solar Cities to promote the usage
of Renewable Energy in urban areas by providing support to Municipal Corporations for the
preparation and implementation of a road map to develop their cities as Solar Cities. An indicative
target of 60 cities/towns, with atleast one in each State, has been set for the 11th Plan period (2007-
2012). In a major development under this scheme, the Government of Andhra Pradesh has recently
(December 2009) announced the development of a solar farm cluster called Solar City on a 10,000
acre land at Kadiri in Anantapur district. Solar City is expected to attract investments worth Rs. 3,000
Cr in the first phase. Four firms – Sunborne, Lanco Solar,
AES Solar and Titan Energy – have signed a Memorandum of Understanding with the state to set up
establishment in Solar City. These companies will be the anchor units in Solar City and have a
proposed combined capacity of 2,000 MW.
Tamil Nadu has launched India’s largest solar rooftop programme for providing Solar powered Green
Houses (3 lakh houses by 2015-16) under Chief Minister’s Solar powered Green Houses scheme, with
provision of solar powered Home lighting systems with battery backup in 60,000 Green Houses in
2011-12. Another 60000 green houses will be provided with solar lights during 2012-13 at a cost of
Rs.180 crores. This scheme is also first of its kind in India with grid back up.
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 27
FIRST GREEN CONSULTING
The Govt. of Orissa has declared Orissa Renewable Energy Development Agency (OREDA) as the
Nodal Agency (State Competent Authority) to pre-register the proposals from the prospective
developers for holding RPSSGP under JNNSM.
In order to enable the project proponents to get registered with IREDA, the Commission determined
the following generic tariff for Rooftop PV and other Small Solar Power Plants to be commissioned in
the State of Orissa under JNNSM
According to Maharashtra Electricity Regulatory Commission, Regulation 68 of the RE Tariff
Regulations specifies, that the tariff for Solar Rooftop PV projects and other small solar projects will
be Rs 0.50/kWh higher than the Tariff specified for Solar PV projects in the Regulations.
Accordingly, the Tariff for such Projects in FY 2012-13 shall be as follows:
The above Tariff shall be applicable for Solar Rooftop PV and other small solar Projects wherein PPA
are signed after March 31, 2012 and projects are commissioned during FY 2012-13, and the same
shall be valid for a tariff period of 25 years from the Commercial Operation Date (COD).
For the state of Karnataka, the policy is structured as follows
Roof Top Solar Tariff: The Roof Top Grid connected solar KWp level projects of 5 KWp to 100 KWp
will be allowed connecting at 415 V, 3 phase, 11 KV level of distribution system of the licensee in
such a manner that the maximum energy injection will not be more than 70% of the consumption
from the distribution licensee‘s source by the Solar Roof Top consumer. Any injection in a billing
period exceeding 70% of the consumption will be treated as inadvertent and will not be considered
for commercial purpose; neither the deficit is carried forward to next billing period. Such injection will
be settled on Net Basis with the consumption of the said consumer from the distribution licensee’s
source in each billing period.
Particular
Tariff
Period
Levellised Total
Tariff (FY 2012-13)
(Rs/kWh)
Benefit of
Accelerated
Depreciation
(if availed)
(Rs/kWh)
Net Levellised Tariff
(upon adjusting for
Accelerated Depreciation
benefit)
(if availed)
(Rs/kWh)
Solar rooftop PV
and other Small
solar power
Projects
25 11.66 1.65 10.01
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 28
FIRST GREEN CONSULTING
Roof Top Grid connected solar power quantum fed to the Grid will be eligible for a Tariff of Rs 3.40
per KWh along with Net Metering facility. If any incentives available from Ministry of New and
Renewable Energy Government of India, it will be passed on to the Developer. However, Roof Top
systems will be additionally eligible for any other subsidies extended to the Roof Top Projects.
Solar Photo Voltaic systems below 2 KWp will be battery backed isolated stand alone systems.
Isolated Solar Photo Voltaic sources up to 200 KWp will be for Rural Applications
Roof Top small scale Solar PV Installations will be encouraged with Net Metering facility to feed
surplus power generated to the Grid.
Under Solar Karnataka Programme it is targeted for 25000 Solar Roof Tops of 5 to 10 kwp with
Net Metering will be taken up with a 250 MW potential during next 5 years with a generation potential
of 350 MU.
Regulatory bodies responsible for Rooftop systems:
Karnataka Electricity Regulatory Commission: Concurrence for Solar Tariff and Roof Top Net
Metering. Energy Department, Government of Karnataka: Approval is required to take up MW
scale and Roof Top Solar projects.
The multi-storey buildings in the state of West Bengal will have the obligation to install solar panels
on the rooftops for power generation, according to a new policy approved by the state government on
May 23, 2012, regarding power generation from renewable energy sources. The policy was cleared by
the state cabinet committee on infrastructure and industry.
The new policy mandates the multi-storey buildings to have solar panels installed on the rooftops.
Power generated has to be transferred to grid and residents will draw electricity from it. The
additional amount will be adjusted in their monthly bills.
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 29
FIRST GREEN CONSULTING
Annexure 4
System Sizing of a typical rooftop system
Solar Rooftop Systems: Alternative to Support Growing Energy Need Page 31
FIRST GREEN CONSULTING
Annexure 5: Technical Specifications of PV Modules and Inverter Systems
The Rooftop PV and Small Solar Power Projects deploying PV modules and Inverter systems should
comply with the IEC/ BIS standards and the standards specified by CERC to be considered technically
qualified.
The equipment quality to be used should meet the guidelines for engineering design included in the
standards and codes listed in the relevant ISI and other standards, such as:
i. IEEE 928: Recommended Criteria for Terrestrial PV power systems.
ii. IEEE 929 Recommended practice for utility interface of residential and intermediate PV systems.
iii. IEEE 519 Guide for harmonic control and reactive compensation of Static Power Controllers.
iv. National Electrical NFPA 70-1990 (USA) or equipment national standard.
v. National Electrical Safety Code ANSI C2 (USA) or equipment national standard.
vi. IEC : 61215 (2005)- Crystalline silicon terrestrial photovoltaic (PV) modules – Design
qualification and type approval
vii. vii. IEC: 61730 -1, -2 Photovoltaic (PV) module safety qualification Part 2: Requirements
for testing
viii. IEC: 60904-1(2006) Photovoltaic Devices- Part-I: Measurement of Photovoltaic current-
Voltage Characteristic
ix. IS 9000 Basic environmental testing procedure for Electronic and electrical items.