Transcend Solar systems & Solutions
Transferring to Green
CONTENTS
Executive
summary............................................................................
Salient features
INTRODUCTION
ELEMENTS INCLUDED IN A SYSTEM OF PHOTOVOLTAIC CONVERSION
EXISTING POWER SUPPLY ARRANGEMENTS:
LV DISTRIBUTION SYSTEM LAYOUT
Solar availability and the details of the irradiances:
PROTECTION AND CONTROLS:
INTEGRATION OF PV POWER WITH GRID:
EXECUTIVE SUMMARY
The proposed Roof Top Solar Photovoltaic Power Plant at the site
of 186sq.m^2 would utilize vacant area of about 952 sq. m.
available on the roof top. The SPV power plant with proposed
capacity of 20 kWp would be connected to grid. No battery storage
has been provided. It would meet partial load of the building
during working days and feed the surplus power available to the
grid during week end and holidays.
The 20 kWp SPV power plant is estimated to afford average annual
energy feed of 38.44 (PCU) as 94% and losses as 3% in the DC and AC
system. The Plant would
operate at a daily capacity utilization factor of 8.5%. The
energy available from
the Plant would vary from a minimum of 2.5 MWh during the month
of November to a maximum of 4.092 MWh during the month of
March.
The SPV Power Plant is estimated to cost Rs. 20 Lakhs based on
the normative
SALIENT FEATURES
1) Location
a) Site Address: The Madras Pharmaceuticals,Karpakkam
b) Latitude: +13.09 (13°05'24"N)
c) Longitude: +80.27 (80°16'12"E)
2) Area of the SPV plant
a) Length
b) Width
c) Location
3) SPV Power Plant
a) Output20Kwp
b) No.of Modules80
c) No.of modules in series40
d) DC bus1No.
4) Technical details of the SPV module
a) PV module type: Poly crystalline
b) Physical dimensions
i) Length: 1639mm
ii) Width:982mm
iii) Thickness: 35mm
c) Electrical Parameters
5) Maximum power rating
i) Rated current:29.95 V
ii) Rated voltage: 8.35 A
iii) Short circuit current: 8.95A
iv) Open circuit voltage: 37.25V
6) Mounting Arrangement
i) Mounting: Ms structure with coating
ii) Tilt angle(slope) of PV module: 13 deg
7) Inverter/Power Conditioning Unit(PCU)
i. No.of units: 1 Nos.
ii. Rated capacity: 20kW
iii. Input voltage range: 350 – 1000V
iv. Output voltage: 415V
v. Frequency: 50Hz
vi. Efficiency: 98.7%
8) Grid connection details
i) Electrical parameters for interconnection
9) Annual Energy Generation
Cost Estimate:
Construction time
INTRODUCTION
In one minute, the sun provides enough energy to supply the
world‟s energy needs for one year. In one day, it provides more
energy than the world‟s population could consume in 27years. The
energy is free and the supply is unlimited. All we need to do is
find a way to use it. The largest solar electric generating plant
in the world produces a maximum of354 megawatts (MW) of electricity
and is located at Kramer Junction, California. Since India has
abundant sources of RE especially sunlight, it can cater to all the
energy needs of the country. The country receives an average
radiation of 5 KWh per square meter (m) per day and with 2300 to
3200 sunshine hours per year. The potential of solar photovoltaic
has therefore been estimated at 20 MW per square km.
Conversion from Solar energy into Electrical energy
There are 2 ways to convert the solar energy into electrical
energy
1) Solar thermal
2) Solar photovoltaic system
Solar photovoltaic systems are superior when compared to the
solar thermal system where the solar thermal system can only use
the direct irradiance of the power generation whereas the solar
photovoltaic system can convert the diffuse irradiance as well.
That means that, they can produce electricity even with cloud
–covered skies.
So the Solar photovoltaic solutions are preferred one when
compare to solar thermal systems.
ELEMENTS INCLUDED IN A SYSTEM OF PHOTOVOLTAIC CONVERSION
The main elements that can be included in a system of
photovoltaic systems are
· Solar Panels
The solar panel is the power source of all photovoltaic
Installation. It is the result of a set of photovoltaic cells in
series and parallel. Solar panel gives power to battery or inverter
through charge controller (Regulator).
· Solar charge controllers:
It is the element to protect the battery against to risking
situations as overloads and over discharges. The theoretical
formulation of the model can be simple, although it is necessary to
consider the peculiar discontinuities of the model and the
inter-performance with the rest of the analyzed models.
· Inverter:
The inverter allows transforming the DC current to AC. A
photovoltaic installation that incorporates an inverter can belong
to two different situations, based on the characteristics of the
alternating network. In first an isolated system, where the
inverter is the element of the network and has to feed the set of
loads and in second situation the inverter is connected to the
public network, to which it sends the energy generated by the
system.
· Batteries
Normally they have been considered as a simple element of
storage of
Electrical energy. Batteries are often sold with a PV system.
The primary purpose is to store the electricity not immediately
used, which could be used at some later time. With net metering,
the value of batteries is less because the utility grid basically
acts as a storage facility. For a reliable generation system that
can function independent of the utility grid, however, batteries
may be a viable component to the total system. Backup generators
may be included in a system to provide power when the PV system is
not operating, and are generally included when systems are not grid
connected.
Types of Photovoltaic systems
There are two types of photovoltaic system generally used in the
houses, Industries and power plant generation.
· Grid Connected PV Systems
These systems are connected to a broader electricity network.
The PV system is connected to the utility grid using a high quality
inverter, which converts DC power from the solar array into AC
power that conforms to the grid‟s electrical requirements. During
the day, the solar electricity generated by the system is either
used immediately or sold off to electricity supply companies. In
the evening, when the system is unable to supply immediate power,
electricity can be bought back from the network.
· Standalone Systems:
PV systems not connected to the electric utility grid are known
as Off Grid PV Systems and also called „stand-alone systems.‟
direct systems use the PV Power immediately as it is produced,
while battery storage systems can store energy to be used at a
later time, either at night or during cloudy weather. These systems
are used in isolation of electricity grids, and may be lighting and
general loads. PV systems also provide invaluable and affordable
electricity in developing countries like India, where conventional
electricity grids are unreliable or non-existent.
SITE DESCRIPTION:
The roof top is having an area of close to 952.8 sq.m of area
where it is proposed to utilize the vacant area on the roof top for
installation of 20 kWp which could serve as a grid connected system
and could be used for collection of data for analysis on the of
availability of solar power.
Plant is having around sq.ft of rooftop which will be used to
for installing ON grid solar solutions to the industry.
The data are collected from the recent metrological data, the
details as follows.
Chennai, India - Solar energy and surface
meteorology
From the above figure of the data the average solar irradiance
is 5.273kWh/m^2/day, and the maximum wind speed is 5.52m/sec. The
sun path direction of the solar system is
The basic information at the site is:
Latitude: +13.09 (13°05'24"N)Longitude: +80.27 (80°16'12"E)
FUNCTIONAL DESCRIPTION OF SPV POWER SYSTEM
The solar PV system shall be designed with either mono/ poly
crystalline silicon modules or using thin film photovoltaic cells
or any other superior technology having higher efficiency.
Three key elements in a solar cell form the basis of their
manufacturing technology. The first is the semiconductor, which
absorbs light and converts sit into electron-hole pairs. The second
is the semiconductor junction, which separates the photo-generated
carriers (electrons and holes), and the third is the contacts on
the front and back of the cell that allow the current to flow to
the external circuit. The two main categories of technology are
defined by the choice of the semiconductor: either crystalline
silicon in a wafer form
or thin films of other materials.
The grid interactive roof top solar PV system generally
comprises the
following equipment.
i) SPV Power Source
ii) Inverter (PCU)
iii) Mounting Structure
iv) AC and DC Cables
v) Earthing equipment /material
vi) Junction Boxes or combiners
vii) Instruments and protection equipments
Photovoltaic solar system use the light available from the sun
to generate
electricity and feed this into the main electricity grid or load
as the case may
be. The PV panels convert the light reaching them into DC power.
The amount of power they produce is roughly proportional to the
intensity and the angle of the light reaching them. They are
therefore positioned to take maximum advantage of available
sunlight within site constraints. Maximum power is obtained when
the panels are able to 'track' the sun's movements during the day
and the various seasons. However, these tracking mechanisms tend to
add a fair bit to the cost of the system, so a most of
installations either have fixed panels or compromise by
Incorporating some limited manual adjustments, which take into
account the
different 'elevations' of the sun at various times of the year.
The best elevations vary with the latitude of the load
location.
The power generating capacity of a photovoltaic system is
denoted in Kilowatt peak (measured at standard test conditions of
solar radiation of 1000 W per m2). A common rule of thumb is that
average power is equal to 20% of peak power, so that each peak
kilowatt of solar array output power corresponds to energy
production of 4.8 kWh per day (24 hours x 1 kW x20% = 4.8 kWh)
Solar photovoltaic modules can be developed in various
combinations depending upon the requirements of the voltage and
power output to be taken from the solar plant. No. of cells and
modules may vary depending upon the manufacturer prudent
practice
Inverter
i) The DC power produced is fed to inverter for conversion into
AC.
ii) The output of the inverter must synchronize automatically to
the grid system based on the voltage and the frequency.
iii) Inverter efficiency of min.94% is considered in the PV
system
PROTECTION AND CONTROLS:
i) Inverter shall be provided with islanding protection to
isolate it from the grid in case of no supply, under voltage and
over voltage conditions so that in no case there is any chance of
accident.
ii.) In addition to above, PV systems shall be provided with
adequate rating fuses, fuses on inverter input side (DC) as well as
output side (AC) side for overload and short circuit protection and
disconnecting switches to isolate the DC and AC system for
maintenances are needed.
ii) Fuses of adequate rating shall also be provided in each
solar array module to protect them against short circuit.
ANNUAL ENERGY GENERATION:
The annual energy generation from the SPV power plant has been
worked out
based on the data on mean global solar radiant exposure over
puducherry at
The mean global solar radiant exposure for a complete year is
5.27kWh/m^2/day. Considering the efficiency of PV module at 16% and
temperature coefficient of 4.4 % per deg C, the annual energy
generation feed into the grid is estimated as 38.44 MWh. This takes
into consideration an efficiency of the Power Conditioning
Unit (PCU) as 97% and losses in the DC and AC system as 3% each
up to the
point of interconnection. The month wise energy generation
during the year is
given below.
INTEGRATION OF PV POWER WITH GRID:
The output power from SPV would be fed to the inverter which
converts DC
Produced by SPV array to AC and feeds it into the main
electricity grid after
Synchronization. In case of grid failure, or low or high
voltage, solar PV system shall be out of synchronization and shall
be disconnected from the grid. Once the DG set comes into service
PV system shall again be synchronized with DG supply and load
requirement would be met to the extent of availability of
power.
Inverter shall have the software and controls capable of
operating the complete system for safe and efficient operation and
includes the Islanding protection, Over voltage/ under voltage
protection, Ground fault /short circuit protection system,
communication equipment such as modems, web box etc, DC reverse
polarity protection, Grid monitoring of all the phases & pole
sensitive residual current monitoring unit, protection against
voltage fluctuations in the grid & protection against internal
faults in the power conditioner, operational errors and switching
transients etc.
The output power from inverter would be fed to the panel of
common AC bus system where both the Grid and DG sets are connected.
The solar power would be used locally in on working days to the
extent of load in the building and the generation over and above
the requirement of the building would be fed into the grid. On the
week end and other holidays, almost the entire energy from the SPV
module would be fed into the grid. The connection of the grid
connected SPV power plant with the existing power supply system is
shown
in the diagram below.
(GRID )
COMMUNICATION INTERFACE:
The project envisages a communication interface which shall be
able to
support ( These facilities are being provided as this is a
demonstration project)
· Real time data logging
· Event logging
· Supervisory control
· Operational modes
· Set point editing
Communication System shall be an integral part of inverter. All
current values, previous values up to 40 days and the average
values of major parameters shall be available on the digital
bus.
The following parameters shall be measured, displayed and
recorded/logged. Daily plotting of graphs for various parameters
shall also be available on demand. (These facilities are being
provided as this is a demonstration project)
· 15 minute, Daily, monthly & Annual energy generated by the
solar system (kWh)
· Solar system temperature
· Ambient temperature
· Solar irradiation/isolation
· AC and DC side voltage and currents
· Power factor on AC side
· DC injection into the grid (one time measurement at the time
of installation)
· Total Current Harmonics distortion in the AC side
· Total Voltage Harmonic distortion in AC side
· Efficiency of the inverter
· Solar system efficiency
Display of I-V curve of the solar system any other parameter
considered necessary by supplier of the solar PV system based on
prudent practice.
Data logger system and the software for study of effect of
various environmental & grid parameters on energy generated by
the solar system and various analysis would be required to be
provided.
The communication interface shall be suitable to be connected to
local computer and also remotely via the Web using either a
standard modem or a GSM / WIFI modem.
Layout of the Site and the proposed solar power plant
location
(39.7 m)
(Proposed Solar Installation)
(24m)
(4.6m) (24.3m)
(9.8m)
Connection diagram of the whole system.
(Combiner Box with Forward diode InverterNet meter +
GridMCCBPersonnel Computer(data logging))
JanFebMarAprilMayJuneJulyAugSepOctNovDec4.93000000000000245.836.66.746.185.264.764.88999999999999975.084.54.15999999999999754.3199999999999985JanFebMarAprilMayJuneJulyAugSepOctNovDec312831303130313130313031JanFebMarAprilMayJuneJulyAugSepOctNovDec3056599.9999999977326480040920004044000.00000000053831599.99999999773155999.9999999977295120030318003048000279000024960002678400.0000000005JanFebMarAprilMayJuneJulyAugSepOctNovDec3.05659999999999873.26480000000000014.09199999999999964.04400000000000053.83159999999999773.15599999999999972.95119999999999873.03179999999999873.0482.792.49599999999999872.6784000000000003