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The
meaning of Maximum Power Point Tracking
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How
Maximum Power Point Tracking works
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MPPT
charge controller |
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Main
features of MPPT charge controller
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The
meaning of Maximum Power Point
Tracking
Maximum Power Point Tracking
or MPPT is the
algorithm that included in electronic
control device use for extracting
maximum available power from PV
panels, which the maximum power
change according to the variations
in parameters such as solar radiation,
ambient temperature and solar
cell temperature.
The MPPT algorithm is implemented
by using microprocessor to check
the PV panels output at all time
that there is no other higher
output power from PV panels in
form of current and voltage from
the solar radiation at that time.
To get the higher power, the MPPT
algorithm checks the PV panels
output, and compares it to the
battery voltage. If a trial shows
what the best power is, it will
move control point to use new
PV panel's voltage and current
output. |
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As
the graph in figure 1 and 2, we
see that at the different solar
radiations, PV panels deliver the
variations in parameters as follows:
1 - Maximum power; Pm
2 - Maximum power voltage; Vpm
3 - Open circuit voltage; Voc
4 - Maximum power current; Ipm
5 - Short circuit current; Isc |
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How
Maximum Power Point Tracking works
The major principle of MPPT is
to extract the maximum available
power from PV panels by making
them operate at the most efficient
voltage. That is to say:
MPPT operates by checking the
output of PV panels, compares
it to the battery voltage, then
fix the best power that PV panels
can put out to charge the battery,
and convert it to the best voltage
to get maximum current into battery.
Besides, it can also supply power
to a DC load, which is connected
directly to the battery.
MPPT is most effective under these
conditions :
1 - Cold weather or winter - Normally,
PV panels work better at cold
temperatures. Although, in winter
the time of sun hours are low,
if the device with MPPT is implemented,
it allows producing more maximum
power but lost less power.
2 - Low battery charge - The lower
the state of charge in the battery,
the more current to a MPPT puts
into the battery.
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| MPPT
charge controller |
A
MPPT charge controller
is the charge controller
with power electronic
control device designed
to control by microprocessor
embedded with MPPT algorithm
firmware to maximize the
amount of current going
into the battery from
PV panels.
A MPPT charge controller
works as DC-DC converter
by using know how of PV
panel and battery characteristics
to get the highest conversion
power output from PV panels
and safely charge battery.
The
converter is classified
into two types : |
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Boost regulator; The PV input
voltage is less than the battery
voltage in system. |
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2.
Buck regulator; The PV input voltage
is greater than the battery voltage
in system. |
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Main features of MPPT
charge controller |
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In
applications where PV panels are
energy source, the MPPT charge
controller is used to correct
for variations in the current-voltage
characteristics of the solar cell
and shown by I-V curve |
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It is necessary to implement the
MPPT charge controller in order
to move the PV panels operating
voltage close to the peak power
point for drawing the maximum
available power from PV panels |
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The
MPPT charge controller allows
the users to use a PV panel with
a higher voltage output than operating
voltage of the battery system.
For example, if the PV panel has
to be placed far away from the
charge controller and battery,
the wire size must be very large
to reduce the voltage drop. With
a MPPT charge controller, users
can wire the PV panel for 24 or
48 volts (depending on the charge
controller and PV panels) and
bring the power into a 12 or 24
volts battery system. This means
it reduces the wire size needed
while retaining the full output
of PV panels. It is a significant
savings. |
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The
MPPT charge controller reduces
the complexity of the system while
the output of the system is high
efficiency. Additionally, it can
be modified to handle more energy
sources. Because the PV panels
output power is used to control
the DC-DC converter directly.
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The
water turbines, wind-power turbines,
etc. MPPT charge controller can
be applied to other renewable
energy sources such as small |
