Roof-Top Grid-Connected PV Power System in Bangladesh
Developed by - RERC
Dr. Rezaul Karim Mazumder
Dr. Subrata Kumar Aditay
Dr. Saiful Hoque
Dr. Habibur Rahman
And
Dept. of Applied Physics, Electronics and
Communication Engineering University of
Dhaka, Dhaka-1000.
Contact Address :
Energy Park, Faculty of
Science
Science Library Campus, University of Dhaka
Dhaka - 1000, Bangladesh
E-mail:
rerc@univdhaka.edu
rercdu@yahoo.com
Ph: +880-2-9677125, 9661920-73/4570
Fax: +880-2-8615583
Website:
http://www.univdhaka.edu/ResearchDetails.php?bodyid=CRE
- Financed by the Ministry of Science and Information & Communication Technology Govt. of the people’s Republic of Bangladesh
Bangladesh is an energy deficit country. Load-shedding and power failure is a daily occurrence. Conventional source of energy in our country is very limited and the supply of energy in the future may not be sufficient for the constant envelopment of the country. Renewable energy resource can be considered as one of the important alternatives and it can play a significant role in the total energy scene of the country.
The most important sources of renewable energy, in the country are
solar, wind, small hydro, biomass, and biogas. Of all the options, solar
energy is the simple, easiest and most viable option. Various private
organizations and NGOs like RAHIMAFROZ, Grameen Shakti, CMS, Energy
Systems, Solar Bangla, Ananda, Microelectronics, Sunwise, ARMCO etc.
have come forward by taking different
projects to utilize solar devices and to provide PV electricity
to the villages in Bangladesh.
Although Solar Home Systems (SHS) are now gradually becoming popular in
Bangladesh and have obtained good dimension, Grid-connected PV systems
can be good power sources in cities and in remote areas where power
generation in the existing grid is needed to be increased.
Grid-connected PV power system:
During sunny days the DC power generated by the PV modules in the system
is converted to AC by power conditioning unit (inverter) and fed into
the local loads.
Any excess solar power is supplied to the power line, and any shortfall
is made up with grid electricity. During nonsun hours, residence loads
are supplied by utility grid alone.
In Roof-top Grid-connected PV systems, PV arrays are installed on the
roof-tops of buildings.
In many countries like Japan, Germany, USA, Australia, Italy government
policies are framed to encourage and popularize this power system by
providing necessary regulations and incentives. Gridconnected PV power
systems in the cities all over the world (where there is sun) will
become a small, but important source of electricity generation in the
next century. The world market for grid-connected photovoltaic systems
is growing rapidly. Fig.1 shows the year wise cumulative installed
grid-connected and offgrid PV Power all over the world and Table-1
indicates the installed PV power as of the end of 2005 by Japan,
Germany, USA, Australia, Spain, Netherlands and Italy.
System
Design and Development:
Realizing the significant potential of this technology a model of 1.1 kW
rooftop grid connected photovoltaic system has been designed, developed
and successfully commissioned at the rooftop of Renewable Energy
Research Centre (RERC), University of Dhaka. A block diagram of the
system is shown in Fig.2. In this design the following factors have been
taken into consideration.
_
Grid interfacing circuitry matching,
_
Effects of voltage fluctuation, harmonic distortion and
stability
_
Over current, over voltage protection and power failure
_
Power conditioning and flickering
_
Safety, bi-directional metering for power tariff
Fig.2 Roof-top Grid connected P
V power system
The designed Roof-top Grid Connected PV
system has the following components:
PV Array:
20 PV panels (BP Solar, India) are connected in series giving a DC output of 140-400V according to intensity of incident radiation. Orientation and tilt angle: Orientation is south-facing and tilt angle is 24.25N . Area covered by PV array is about 11m2. Fig.3 represents PV array mounted on the roof-top of RERC, DU.Inverter:
Inverter (Sunny Boy) that 'inverts' the above DC power from the panels into AC power of 1.1kW/220V/50Hz. The characteristics of the output signal should match the voltage, frequency and power quality limits in the supply network. Fig.4 and Fig.5 shows the photograph of the grid-connected inverter.
Load:
Appliances in the residence that are fed from the inverter, or,
alternatively, from the grid.
Meters:
They register the energy being used from the local supply network or fed
into local supply network.
Local Supply Network: The single-phase network of local supply line. The supply network acts both as a sink for energy or as a backup for low local generation periods. Fig.6 shows the electric wiring of the system. The overall efficiency of the system depends on the efficiency of the PV array and the efficiency of the inverter. The efficiency of the inverter varies with the load level. High efficiency of the inverter can be obtained by running the inverter near full loads.
Specifications of the system:
PV
string:
·
No of PV panel (BP) in series-20
·
Open-Circuit Voltage (VOC) : 20V/panel
·
Short-Circuit Current (ISC) : 4A/panel
·
Power Output : 75 Watt/panel
·
Total output of the string: 1.5kWatt
Inverter
(Sunny Boy):
·
Maximum input current : 10A
·
DC input voltage : 139-400V
·
Max. input power : 1.21kW
·
Nominal output power : 1kW
·
Output AC voltage: 220V, 50HZ
Fig.3 PV array of Grid-connected PV system at Roof-Top of RERC-DU
Practical Results:
The system was run
for several days in different weather conditions. A representative curve
of the generated output power of the system for the input at various
time of a day
is shown in Fig.7.
Efficiency, Input and Output power of, the system were found to be as
follows:
·
Efficiency of
the inverter: 90-93%
·
Input power
(DC): 1000-1300 W
·
(on a typical
semi-cloudy day)
·
Output power
(AC) : 672-1120W
Cost of unit
of electricity Produced:
The cost of unit of electricity produced by this system would depend on
the overall system efficiency, the resource availability, the lifetime
of the system and the interest rate. An economic evaluation of various
sizes of roof-top grid connected systems along with the 1.1kW system
with and without net-metering of 2 times per unit grid-fed benefit
has been done. The results of the analysis for different interest rates are shown in Fig.8. It is observed from the figure that the cost of unit of energy generated by the various sizes of systems are encouraging with net-metering benefit.
Fig.8 Cost of unit of energy versus various sizes of PV
systems
Conclusion:
·
Long time performance study of the system is needed to run successfully
in Bangladeshi environment.
·
The system will be cost effective for users if Bangladesh Government
takes necessary steps to provide subsidy in this field like other
foreign countries. Japan and Germany have adopted a form of net
metering, whereby customers get paid 2 to 8 times what the power company
charges them for any surplus they supply back to the grid.
·
Government regulation for net metering and use of grid-connected PV
system should be framed.
·
Extensive demonstration is required to popularize the system.
·
However, further work is needed to evaluate impact on system lifetime,
reliability, and economic and environmental cost.
Acknowledgement:
I would like to
express my sincere thanks to Dr. Subrata Kumar Aditay, Dr. Saiful Huque,
Dr. Habubur Rahman Mr.
Shamim Kaiser and Mr. Asif Anawar for active
participation and help. I am also grateful to the Ministry of
Science and Information & Communication Technology for financial support
for the project.
Contact persons:
Dr. Rezaul Karim
Mazumder rkmeteulabd@yahoo.com
Dr. Subrata Kumar
Aditay skaditya_du@yahoo.com
Dr. Habibur
Rahman <habib_ape70@yahoo.com>
Grid-connected solar power shines at DU campus
Dr. Rezaul Karim Mazumder
Fig 2: The author looks at the wiring diagram of the system. Photo:
Anisur Rahman
Would you like to be a proud owner of an electric
power generator? Would you like to produce clean and pollution-free
green power without fuel at your home? Would you like to earn money by
feeding your surplus power to the national grid from this system?
Yes, you too can have it, if you have a bright sunny roof-top or a
compound at your home.
Our country is a low-economy country and per-capita energy consumption
is one of the lowest in the world. The conventional resources in
The only dependable indigenous gas, which is the major source of primary
energy in the country, is used mainly for the production of electricity
and fertilizer. According to expert's opinion our gas reserves will be
exhausted within 2020. Therefore, we must find alternative sources of
energy to maintain the energy supply of our country.
Renewable energy, which is environment friendly, inexhaustible and
sustainable, can be considered as one of the important alternatives and
it can play a significant role in the energy scene of the country. The
most viable sources of renewable energy, in the country are solar, wind,
biomass, and biogas. At present contribution of energy from solar and
wind is only 0.1%.
It is encouraging that private organisations and NGOs have come forward
by taking different projects to utilize solar devices and to provide
photovoltaic (PV) electricity to villages in Bangladesh where national
grid line has not yet reached.
Today, Solar Home Systems (SHS) are gradually becoming popular in the
rural areas in
The power produced by the roof-top grid-connected PV system can be used
to supply local loads, with the excess energy fed into the local grid
for use by other customers. At night, the local loads are simply
supplied by the grid power. If the PV system is large enough, it can
supply more energy into the grid than is used by local loads. Instead of
receiving a bill every month from the utility supply office, the owner
of the system would then be able to earn money by generating surplus
electricity.
Grid-connected PV power systems are being installed in cities in
different countries of the world. Government policies are being framed
to encourage and popularize this system by providing necessary
regulations and incentives in many developed and developing countries.
From the gradual decrease of prices and increased rate of installation
of the systems in the cities all over the world it can be easily
comprehended that this system will become an important source of
electricity in a very short time in the urban areas.
Roof-top grid-connected PV systems are also being installed in our
neighboring countries like
Realizing the significant potential of this technology a model of 1.1kW
rooftop grid connected photovoltaic system has been developed and
successfully installed (Fig.1) at the roof-top of Renewable Energy
Research Centre (RERC), Dhaka University under the financial assistance
of the Ministry of Science and Information & Communication Technology.
Wiring diagram of the system is shown in Fig.2.
The installed system was run for several days in different weather
conditions and the performance was found to be quite satisfactory.
To understand the financial viability of the system, a preliminary
economic analysis of the 1.1kW roof-top grid-connected PV systems along
with various sizes (Table) has been made. In the analysis standard
methods of economics have been utilized considering various factors,
viz., capital cost, life-cycle of the system, interest rate, inflation
rate, operation and maintenance cost with and without net metering
benefit. The above estimation was made by considering an average demand
of 3000kWh for a four-member family. It is also seen from the table that
a system of 2kW power for a single house-hold can produce surplus energy
that can be fed to the national grid.
For 0% to 10% interest rates and 10% depreciation the unit-price of
electricity with and without net-metering facilities will be
respectively Tk.4.85-15.14 and Tk.4.85-15.14 only. As the system size
becomes larger, the unit-price with net-metering decreases rapidly. The
unit-price of electricity for the 1.1kW system at the above interest
rates and depreciation is from 6.18 to 19.32 taka only.
At present
