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9. PPT.pptx
1. DESIGN OF PHOTOVOLTAIC SYSTEMS FOR
STANDALONEAPPLICATIONS
BY
Dr.V.SHANMUGASUNDARAM
Department of Electrical and Electronics Engineering
Sona College of Technology , Salem
Contact: +91 9894640610
Email: shanmugasundaram@sonatech.ac.in
2. OUTLINE
INTRODUCTIONABOUT SOLAR CELLS/MODULES
TYPES OF SOLAR CELLS/MODULES
SOLAR STRING/ARRAY
COMPLETE SOLAR PV SYSTEMS
BALANCE OF SYSTEM
LOAD CALCULATIONS
DESIGN OF STANALONE PV SYSTEMS AND APPLICATIONS
CASESTUDY
RESEARCH IN PV SYSTEMS
3.
4.
5.
6. Physics of PV cell
Solar Light energy is converted
into Electrical Energy.
13. Differentiation of Solar cell to Solar array
Solar cells produce less
voltage(Half V.)
Cells connected in series to
produce more voltage and form a
module(50V per module)
Modules connected in series to
increase voltage but current
remains same.(200V per string)
Strings are connected in parallel
to increase the current and form
an array.
17. Factors that impact
Energy output
Climate-Weather &
Location
High temperatures
can reduce solar
panel efficiency
Panel Orientation
Shading
Natural Efficiency
drop
And more…
18. Solar panel efficiency drops about
0.5% to 1.0% every year.
30. PV system Design
Criteria:
1. Determine power consumption
demands
2. Size the PV modules
3. Inverter sizing
4. Battery sizing
5. Solar charge controller sizing
31. 1. Determine power
consumption demands
It is required to find the total power
and energy consumption of all
loads that is supplied by the PV
system.
Calculate the total watt hours per
day for each appliance used.
Add the watt hours needed for all
appliances together to get the total
watt hours per day which must be
delivered to the appliances.
32. Calculate the total watt hours per day needed from the PV modules
33. 2. Size the PV
modules
Different size of PV modules will
produce different amount of power
To find out the sizing of PV module the
total peak watts produced needs.
The peak watts produced depends on
(i) size of the PV module
(ii) Climate of site location
34. We have to consider Panel generation factor, which is different in each site
location.
For the panel generation factor is 3.43
(a) Calculate the total watt peak rating needed for PV modules
35. Number of PV panels system=
Result is the minimum number of PV panels. If more PV
panels are installed the system will perform better and
battery life will be improved.
If fewer PV modules are used the system may not work at
all during cloudy periods and battery life will be
shortened.
36. Comparison of
PV modules
It is best to make comparisons based on current
information provided by manufacturers, combined with
the specific requirements of your application.
Two figures that are useful in comparing modules are
The modules’ price per watt and
The rated power output per area (or efficiency).
37. 1.Calculate cost per watt by:
cost per watt =Module’s price/ Its rated
output in watts.
2. Calculate the watts per area,
Watts per area =Rated output/ Its area
38. 3. Inverter
sizing
Converts DC output
of solar panels into
a clean AC current
for Home
appliances or to
grid lines.
The input rating
should never be
less than the total
watt of appliances
The inverter must
have some nominal
voltage as your
battery
For standalone
systems, the
inverter must be
large enough to
handle the total
amount of watts u
will be using at one
time.
39. The inverter size should be 25-30%
bigger than total watts of appliances.
In case of appliance type is motor or
compressor then inverter size should
be minimum 3 times the capacity of
those appliances and must be added
to the inverter capacity to handle
surge current during starting.
40. For grid tie systems or grid connected systems, the input rating of the
inverter should be same as PV array rating to allow for safe and
efficient operation.
41. 1. Battery (Cont..,)
Charge
Electrical energy -> Chemical
energy
Discharge
Chemical energy -> Electrical energy
Charging – Discharging Cycle
BOS – BATTERIES (Cont..,)
45. Characteristics of various batteries – Choosing the Best one
Flooded lead acid battery Valve regulated lead acid battery Lithium ion battery
Applicable for solar PV applications Applicable for solar PV & electric
vehicle applications
Especially designed for electric vehicle
application
Water loss during charging occurs
making it dry
H2 and O2 produced arecombined
again to form water
Positive electrode is metal oxide.
Negative electrode is carbon and the
electrolyte is a lithium salt in an organic
solvent.
Electrolyte level should be above the
top of plates
No water refilling is required & acid
will not leak
No water refilling is required & acid will
not leak
Contains an excess of electrolyte
fluid so that the plates are completely
submerged
Acid is gelled or put into a sponge like
glass mat so that can be operated in
any position
It can be operated in any position
Scheduled maintenance Totally maintenance free Totally maintenance free
Heavy Weight Weight lesser than FLA Very much Lesser in Weight when
compared to FLA & VRLA
BATTERIES (Cont..,)
46. 4.Battery sizing
Stores energy for supplying to electrical appliances.
Battery type recommended for solar PV is Deep cycle
battery.
Deep cycle battery is specifically designed for to be
discharged to low energy level and rapid recharged or
cycle charged and discharged day after day for years.
The battery should be large enough to store sufficient
energy to operate the appliances at night and cloudy
days.
47. Days of Autonomy: No of days that you need the system
to operate when there is no power produced by
PV panels.
48. 5. Solar charge controller
sizing
Used to regulate the
voltage and current
coming from solar
panel and voltage to
the battery. Prevents
battery from
overcharging and
prolongs battery life.
Select the solar charge
controller to match the
voltage of PV array and
batteries.
Identify which type
of solar charge
controller is right for
your application.
Make sure that solar
charge controller has
enough capacity to
handle the current
from PV array.
49. Charge Controller
A charge controller (or) charge regulator (or) battery regulator limits the voltage and current preventing from over
charging, over discharging of batteries and other Dc loads.
CHARGE
CONTROLLER
Overcharging Leads to explosion and may reduce battery performance or
lifespan and may pose a safety risk.
overcharging
50. Need of Charge controller
Charge Controller (Cont..,)
Maximum power voltage (Vm) = 17 V
Maximum power current (Im) = 2.88A
Maximum Power (Pm) = 50W
Solar Source Battery Load
Nominal Voltage = 12 V
Capacity = 2Ah
Charging current = 0.2 to 0.4A
Solution:
1. DC-Dc conversion Buck Method (17V to 12V)
2. Constant voltage charging (According to battery charging chart)
3. Satisfying the charging current
CHARGE CONTROLLER
(Cont..,)
51. Charge Controller (Cont..,)
Functions of charge controller:
1. The primary role is to manage
charging the battery bank, prevent
it from overcharging and many
control the rate of the current and
voltage at which it charges.
are rated for voltage
and exceeding that
can lead to permanent
2. Batteries
capacity,
voltage
battery damage and loss of
functionality over time.
CHARGE CONTROLLER
(Cont..,)
53. Difference Between PWM & MPPT Charge controller
PWM CHARGE CONTROLLER MPPT CHARGE CONTROLLER
Good low-cost option Higher end
Applicable for smaller systems Applicable for larger systems
Concentrates only on Voltage Concentrates both on Voltage and
current
No algorithm, depends on duty cycle Contains more than 25 Algorithms to
harvest maximum power from solar panels
Efficiency is Good Efficiency is better than PWM method
CHARGE CONTROLLER
(Cont..,)
54. Sizing of the controller depends on
1. Total PV current which is delivered to the controller and
2. Depends on PV panel configuration (series or parallel).
55. According to standard practice
Sizing of solar controller is to take the short circuit
current(Isc) of the PV array and multiply it by 1.3
56.
57. MPPT controller suitable for
Cold
Cloudy
Far from equator
Winter time
25 to 30% more power
68. CASESTUDY
Your house has the following usage:
One 18 W Fluorescent Lamp with electronic ballast used for 4 Hours per
day.
One 60 W fan used for 2 Hours per day.
One 75 W refrigerator that runs 24 Hours per day with compressor run 12
Hours and off 12 Hours.
The system will be powered by 12V DC, 110Wp PV module.
69. Sl.N
o
Device Power(watts) Hours used
per day
Energy Watt
Hours
1. Fluorescent Lamp 18 4 72
2. Fan 60 2 120
3. Refrigerator 75 24(12 hrs
compressor on
& 12 hrs off)
900
153 1092
Total Load=153 W
Total Energy required by Watt Hours=1092 Wh
70. Step-1
Total appliances =[18*4]+[60*2]+[75*24*(1/2)]
(Watt hrs per day) = 72+120+900
= 1,092 WattHour.
Total Watt-Hour by PV = 1092*1.3
= 1419.6 WattHours.
Note: 1.3 is for safety purpose. ie 130% of rating
71. Step-2 (Number of panels)
= (1419.6/3.43*110)
= 3.7625
= 4 panels
4 panels of 110W panels needed
(Note: Power Generation Hours normally 5 to 8 hours)
Panel Power Generation factor=0.44 for 7.6 hours
=0.45*7.6=3.43
72. Step-3-Inverter sizing
Inverter size= 25 to 30% bigger than total watts of
appliances
Total Watt = 18+60+75=153W
Of appliances
73. Inverter size= 25 to 30% bigger than total watts of
appliances
Inverter size= 153+(153*0.3)
= 198
=Rated Load(watts)/(Inverter PF)=153/(0.8)
=191.25
So the inverter size should be between 191.25 to 198.9W
77. Solar charge controller rating= (4 strings*7.5A)*1.3
=39A
So the solar charge controller should be rated at 40A, 12V or greater.
78. The charge controllers still require lower voltages of 12V, 24V or 48V to
match the voltage of the battery string.
79. Result
Sl.N
o
Parameters Rating
1 Total watt Hour by PV 1420WH
2 Number of panels 4 panels of 110Wp
3 Inverter size 198W
4 Battery 12V, 600A, 3 days of
Autonomy
5 Solar Charge controller 40A
80.
81. Comparison between String inverters
and Microinverters
Sl.N
o.
String Inverters Microinverters
1. Entire system affected by one module All modules controlled independently
2. Susceptible to soiling, shading and
module defects.
Resilient to environmental factors.
3. For Ex. Leaf shading reduces its
percentage to half.
Compared to string inverters its efficiency is
increased by 20%
82. Drawbacks of
string inverters
1. When a part of the solar panel
shaded then the output of the whole
string is reduced to the level of its
weakest panel.
2. Each string must have equal
number of solar panels, have to be
installed in a same angle and have to
be of same type. Small solar system
only affected much.
3. In case of emergency the utility
grid can be shutdown but not the
solar panel. In this condition cables
from the roof to inverter will still be
under high tension.
85. Microinverters
Installed under every
solar panel &
converts the DC to
AC.
Every microinverter
connected to grid
independent from
other microinverters.
When one panel gets
affected, it will not
affect the
performance of other
panels.
The right voltage is
found through a
technique called
MPPT.
When the power fails,
the microinverter
slows down and stop
feeding the power
into the cables.
Microinverters
expensive than string
inverters.
86. DC power
optimizers
Splits traditional
inverters into 2 products
1. Power optimizers
2. Simplified inverters
Optimizers installed
under each panel and
turning them into
intelligent modules.
87. By using panel level tracking
and real time adjustments of
current and voltage, the power
optimizers maximize the power
output to the optimal working
point of each panel.
Due to shading the
underperformed panels don’t
affect the output of the other
panels
88. During power shutdown in the grid, power optimizers reduce
the power output of each panel to a low and safe voltage.
Microinverters and power optimizers are Module Level
Power Electronics(MLPEs)
92. Courtesy:
MIT news
Researchers develop a
roadmap for growth of new
solar cells
February 6, 2020
Solar cells based on
perovskites — a broad
category of compounds
characterized by a certain
arrangement of their
molecular structure — could
provide dramatic
improvements in solar
installations.
