Rooftop Solar Plants a Viable Business Opportunity.
Solar rooftop installations are a good investment option considering both tangible and intangible benefits.
For
organisations planning to shift from conventional energy to solar power
use, a rooftop solar photovoltaic (PV) power plant can not only be a
money saver but also money spinner with excess power supplied to the
utility grid. While the Ministry of New and Renewable Energy (MNRE) is
still in the process of laying down specificationsfor incentives,
experts feel that with the right policies and execution, solar rooftop
installations can be a hot trend in green technology. It is a profitabl
business concept, and hence a viable investment option.
Installation and Requirements
When
solar PV modules are installed on a building’s rooftop to generate
solar power, it is called a rooftop power plant. Rooftop PV installation
can either be done for standalone use or to feed into the grid.
Some
of the factors to consider before installing a solar power plant on
your building’s rooftop include electrical load, current rate, roof
size, load capacity and geographic location of the building. The subsidy
given by the central and state governments, local utilities, and local
community regulations and incentives are also some key determinants in
the evaluation.
Rooftop solar arrays are best installed on a
large and flatroof where direct sunlight without shadow from the
surrounding structures is available. If there is shadow on a part of the
terrace during the day, PV solar panels are unable to harvest the sun’s
energy for that period of time. Let us look at the key considerations
while evaluating solar rooftop options.
First, it is important
to have a basic understanding of the components of a solar power system
and how these generate electricity. PV solar power systems are very
simple electric power generating systems comprising the following basic
components:
1. A set of PV panels that convert sunlight (photons) into direct-current (DC) electricity
2. A racking system that firml holds the panels to the roof, exposing these to the sun at an advantageous angle
3. Inverters that convert DC electricity into alternating current (AC) electricity
4. Wiring that connects everything
5.
A storage battery (in the case of a grid-fed power plant, a large-sized
battery is not necessary to store and use that power after sunset)
6. A variety of means to tilt the panels toward the sun to generate more electricity
7. Energy meters to record the en-ergy that is supplied to the grid
8. Junction boxes
9. Earthing kits
Currently,
commercially available silicon-based solar PV panels are made from
solar cells encased in a special type of toughened glass. Silicon solar
modules have been in the fieldfor more than 50 years and perform quite
predictably. These are guaranteed for 25 years of feld life but the
power yield drops about 0.6 per cent a year. One can use monocrystalline
(made from a single crystal) or polycrystalline (made from multiple
crystals) panels. Monocrystalline panels are a little more efficientbut
the cost per watt is almost the same.
How to supply solar power to the grid?
If
the solar power generated from a rooftop installation is to be injected
into the grid, one needs to enter into a power purchase agreement (PPA)
with the local distribution utility in whose area the solar system is
located. Under this agreement, a tariff is determined by the appropriate
State Electricity Regulatory Commission (SERC). However, the issues
related to grid integration, metering, measurement and energy accounting
for projects are under consideration with the government.
There
is no cost involved in the transmission of energy unless the power is
transmitted at high tension (HT) levels (11 kV or 33 kV), and special
monitoring and metering hardware are deployed at HT levels. In the
current scenario, metering arrangements for rooftop grid-interactive
power plants are under active consideration by the government.
While
no special arrangements are required to inject power into the grid,
there is a safety aspect that needs to be factored in while transmitting
energy. There is always a risk involved, as when the grid fails the
solar power system automatically stops injecting power into the grid.
This is called islanding, where the inverter isolates itself. This is a
standard feature built into solar power inverters, making these safe for
residential and commercial applications. A standalone feature in the
inverter would enable captive consumption of the solar power generated
in the event of any grid outage.
Copper-indium
gallium-diselenide (CIGS) panels may become the preferred type for
commercial rooftop projects in another fiveyears. These have the
potential to deliver reasonable efficienciesat a lower cost than
traditional crystalline panels. However, the cost per watt may not
necessarily go down, only the panel size per watt may drop. Today, solar
panels (depending on the brand) are bankable, that is, banks loan
capital for their purchase.
The solar energy can be used for
captive consumption or exported to the grid. The electrical energy (DC)
or the solar power generated by the solar PV modules during the sunshine
hours is stored in the batteries for use, as and when required. The
energy stored in the batteries is converted into 230V AC mains using an
inverter. This energy automatically synchronises with the grid and gets
injected into it.
Installation by integrators
Many
solar system installers and owners have had good experience in anchoring
the panel structures. This has to be done scientificallyand with care.
It is possible to have non-anchored installation systems but these need
to be very carefully designed to with-stand heavy winds. Such systems
are designed to connect the solar power system to a roof using weights,
rather than fasteners that must be anchored to the roof.
Solar
installation companies, often called integrators, can complete a small
rooftop project within a few weeks. Before signing a contract with an
integrator, evaluate the roof for solar installation with respect to:
Roof
condition. The roof should be in a good state prior to solar
installation. If it needs significantrepair or replacement, get this
done before installing the solar array.
Space availability. Solar power projects work best on flat roofs without obstructions.
Weight
load. Some roofs are not designed to hold much additional weight.
Ascertain the acceptable weight you can add to your roof before signing a
contract.
Investments involved
Of all the components
of a solar PV plant, solar module accounts for the biggest cost—it can
be 70 per cent of the total project cost. The cost per watt is currently
Rs 130-150 ex-factory. The investment primarily depends upon the size
of the power plant, which varies from a small kilowatt to multi-megawatt
plant. At present, good-quality off-grid rooftop solar power plants can
be installed at a cost of Rs 250,000 per kW.
Under the National
Solar Mission policy, the benchmark price for an off-grid system is Rs
270,000 per kW peak. For a grid-connected system, it is Rs 190,000 per
kW peak. The government also provides a 30 per cent subsidy on the
benchmark price. Installation costs would differ in case of remote
installations and poor site conditions.
Economic advantages
The
total investment per kW in a small power plant, for example, 10kW, will
be the same if not less than in a large 5MW plant. It is therefore
viable to go for small grid-fed plants owned by small privately-owned
utilities. A buying rate of Rs 17 or 18 per unit of electricity from
such plants will attract thousands of small investors like a magnet. In
most areas in India, solar power can then be a fiscallysound investment
that reduces electricity payments immediately, as well as hedges the
small solar plant owners against local utility price increases.
If
solar power is fed into a small city grid like Miraj, Ratnagiri or
Ratlam, all consumers in that area will get cleaner uninterrupted power
from the local copper grid. The high impedance of the local grid helps
power to remain local, improving the local power quality. That’s why all
other countries in the world allow solar plant owners to feed power
into the local grid at the low voltage end.
It therefore makes
sense to set up a solar rooftop plant in cities or towns facing severe
electricity shortages. Today, the cost of generating electricity using a
diesel generation (DG) set is in the range of Rs 20-22 per unit,
whereas generating solar power costs only Rs 13-15 per unit.
Based
on the current prices and assuming that one takes advantage of the 80
per cent depreciation permitted on such investments, in the firstyear
the cost of power per unit (kWh) from a well-maintained solar plant will
be less than Rs 8 per watt for a plant of any capacity between 5 kW and
1 MW. Thus solar rooftop installation is a good investment option
considering both tangible and intangible benefits.
Eligibility criteria for project proponent
While
the government is yet to announce the policy for rooftop grid-connected
power plants, it has laid down certain guidelines for rooftop PV and
other small solar power plants connected to distribution networks at
voltage levels below 33 kV. Hereinafter, the programme is referred to as
Rooftop PV & Small Solar Power Generation Programme (RPSSGP).
Technical criteria.
The project schemes that propose to deploy PV modules and inverter
systems are considered to be technically qualified and eligible for
participation in the RPSSGP scheme only if these comply with relevant
IEC/BIS standards and/or applicable standards as specified by the
Central Electricity Authority (CEA). For solar PV projects to be
selected under this scheme, it is mandatory that these are based on
crystalline silicon technology and use modules manufactured in India.
There will be no mandatory domestic content requirement for projects
based on other technologies. For solar thermal technology, it is
mandatory that the technology is demonstrated and such projects should
be operational for one year. Project proponents should submit
documentary evidence and an undertaking in this regard along with their
applications to the competent authority in the state.
Metering arrangements.
Metering arrangements should be made by the project proponents in
consultation with the distribution utility keeping in view the
guidelines or regulations notified by the respective state electricity
regulatory commissions, if any. Meters should comply with the
requirements of CEA regulations on the meter installation and operation.
Financial criteria.
The project proponents should submit their letters of commitment along
with board resolution for equity investments in the project, calculated
on the basis of Rs 40 million per megawatt on a pro-rata basis.
Infrastructure criteria for land requirement.
The project proponents should make arrangements for land required for
the project as per conditions outlined by respective state competent
authority.
Infrastructure criteria for grid connectivity requirement. The
plant should be designed for interconnection with the grid at the
distribution network at the voltage level depending on the installed
capacity of the rooftop PV or small solar system generator.
(For the complete requirement list please visit www.mnre.gov.in)
The
government is also encouraging the use of rooftop power plants as a
substitute for diesel-consuming and polluting DG sets. Most commercial
buildings are dependent on diesel generators during power cuts.
Investing in a rooftop solar power plant can offset diesel consumption
and make the returns attractive. Added to this, the 30 per cent central
finance assistance (CFA) in the form of capital subsidy would encourage
investors. With a rooftop installation, one can recover the project’s
cost within five t six years. Also, typically, a solar power plant has a
life of 25 years with proper maintenance.
The return on
investment (ROI) completely depends on the power purchase agreement
signed by the project developer. While earlier the buying rate for power
was Rs 17 per unit, today companies are ready to sell it at Rs 11 per
unit, making only a marginal profit.Considering the current trend, the
power purchase price can be estimated at Rs 13-14, so one can expect ROI
within six to seven years.
More benefits for commercial units
Rooftop
installation makes more sense for commercial establishments as these
can utilise the solar power during peak-load daytime periods, thus
saving the money required to set up battery banks. Any amount of power
not used can be stored in a battery bank for use at night when energy
consumption is the least (about 10 per cent compared to the day).
There is no cost involved in the transmission of energy unless the power is transmitted at high tension (HT) levels (11 kV or 33 kV), and special monitoring and metering hardware are deployed at HT levels. In the current scenario, metering arrangements for rooftop grid-interactive power plants are under active consideration by the government.
While no special arrangements are required to inject power into the grid, there is a safety aspect that needs to be factored in while transmitting energy. There is always a risk involved, as when the grid fails the solar power system automatically stops injecting power into the grid. This is called islanding, where the inverter isolates itself. This is a standard feature built into solar power inverters, making these safe for residential and commercial applications. A standalone feature in the inverter would enable captive consumption of the solar power generated in the event of any grid outage.
Technical criteria. The project schemes that propose to deploy PV modules and inverter systems are considered to be technically qualified and eligible for participation in the RPSSGP scheme only if these comply with relevant IEC/BIS standards and/or applicable standards as specified by the Central Electricity Authority (CEA). For solar PV projects to be selected under this scheme, it is mandatory that these are based on crystalline silicon technology and use modules manufactured in India. There will be no mandatory domestic content requirement for projects based on other technologies. For solar thermal technology, it is mandatory that the technology is demonstrated and such projects should be operational for one year. Project proponents should submit documentary evidence and an undertaking in this regard along with their applications to the competent authority in the state.
Metering arrangements. Metering arrangements should be made by the project proponents in consultation with the distribution utility keeping in view the guidelines or regulations notified by the respective state electricity regulatory commissions, if any. Meters should comply with the requirements of CEA regulations on the meter installation and operation.
Financial criteria. The project proponents should submit their letters of commitment along with board resolution for equity investments in the project, calculated on the basis of Rs 40 million per megawatt on a pro-rata basis.
Infrastructure criteria for land requirement. The project proponents should make arrangements for land required for the project as per conditions outlined by respective state competent authority.
Infrastructure criteria for grid connectivity requirement. The plant should be designed for interconnection with the grid at the distribution network at the voltage level depending on the installed capacity of the rooftop PV or small solar system generator.
(For the complete requirement list please visit www.mnre.gov.in)
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