Sunnytech ML2420 User manual

ML Maximum Power Point Tracking (MPPT) Series
ML2420—ML2430—ML2440
Solar Charge and Discharge Controller User Manual
Model
ML2420
ML2430
ML2440
Battery voltage
12V/ 24V
Max. solar panel voltage
100V (25°C), 90V (-25°C)
Charging current
20A
30A
40A
Discharging current
20A

Dear users,
Thank you for choosing our product!
Safety Instructions
1. As this controller deals with voltages that exceed the top limit for human safety, do not
operate it before reading this manual carefully and completing safety operation training.
2. The controller has no internal components that need maintenance or service, thus do
not attempt to disassemble or repair the controller.
3. Install the controller indoors, and avoid component exposure and water intrusion.
4. During operation, the radiator may reach a very high temperature, therefore install the
controller at a place with good ventilation conditions.
5. It's recommended that a fuse or breaker be installed outside the controller.
6. Before installing and wiring the controller, make sure to disconnect the photovoltaic
array and the fuse or breaker close to the battery terminals.
7. After installation, check if all connections are solid and reliable so as to avoid loose
connections that may give rise to dangers caused by heat accumulation.
Warning: means the operation in question is dangerous, and you
should get properly prepared before proceeding.
Note: means the operation in question may cause damage.
Tips: means advice or instruction for the operator.

Table of Contents
1. Product Introduction................................................................................................................ 4
1.1 Product Overview............................................................................................................ 4
1.2 Product Features .............................................................................................................. 4
1.3 Exterior and Interfaces..................................................................................................... 6
1.4 Introduction to Maximum Power Point Tracking Technology........................................ 7
1.5 Charging Stages Introduction.......................................................................................... 9
2. Product Installation................................................................................................................ 12
2.1 Installation Precautions.................................................................................................. 12
2.2 Wiring Specifications..................................................................................................... 13
2.3 Installation and Wiring .................................................................................................. 14
3. Product Operation and Display.............................................................................................. 18
3.1 LED Indicators............................................................................................................... 18
3.2 Key Operations.............................................................................................................. 20
3.3 LCD Startup and Main Interface................................................................................... 21
3.4 Load Mode Setting Interface......................................................................................... 22
3.5 System Parameter Settings ............................................................................................ 23
4. Product Protection Function and System Maintenance......................................................... 24
4.1 Protection Functions...................................................................................................... 24
4.2 System Maintenance...................................................................................................... 26
4.3 Abnormality Display and Warnings............................................................................... 27
5. Product Specification Parameters.......................................................................................... 27
5.1 Electric Parameters........................................................................................................ 27
5.2 Battery Type Default Parameters (parameters set in monitor software) ....................... 28
6. Conversion Efficiency Curve ................................................................................................ 30

6.1 12V System Conversion Efficiency............................................................................... 30
6.1 24V System Conversion Efficiency............................................................................... 30
7. Product Dimensions............................................................................................................... 31
1. Product Introduction
1.1 Product Overview
This product can keep monitoring the solar panel's generating power and tracking the
highest voltage and current values (VI) in real time, enabling the system to charge the
battery in maximum power. It's designed to be used in off-grid solar photovoltaic
systems to coordinate operation of the solar panel, battery and load, functioning as the
core control unit in off-grid photovoltaic systems.
This product features an LCD screen which can dynamically display the operating
status, operating parameters, controller logs, control parameters, etc. Users can
conveniently check parameters by the keys, and modify control parameters to cater to
different system requirements.
The controller utilizes standard Modbus communication protocol, making it easy for
users to check and modify system parameters on their own. Besides, by providing free
monitoring software, we give users the maximum convenience to satisfy their varied
needs for remote monitoring.
With comprehensive electronic fault self-detecting functions and powerful electronic
protection functions built inside the controller, component damage caused by
installation errors or system failures can be avoided to the greatest extent possible.
1.2 Product Features
◆With the advanced dual-peak or multi-peak tracking technology, when the solar panel
is shadowed or part of the panel fails resulting in multiple peaks on the I-V curve, the
controller is still able to accurately track the maximum power point.
◆A built-in maximum power point tracking algorithm can significantly improve the
energy utilization efficiency of photovoltaic systems, and raise the charging efficiency
by 15% to 20% compared with the conventional PWM method.
◆A combination of multiple tracking algorithms enables accurate tracking of the

optimum working point on the I-V curve in an extremely short time.
◆The product boasts an optimum MPPT tracking efficiency of up to 99.9%.
◆Advanced digital power supply technologies raise the circuit's energy conversion
efficiency to as high as 98%.
◆Charging program options are available for different types of batteries including gel
batteries, sealed batteries, open batteries, lithium batteries, etc.
◆The controller features a limited current charging mode. When the solar panel power
exceeds a certain level and the charging current is larger than the rated current, the
controller will automatically lower the charging power and bring the charging current to
the rated level.
◆Instantaneous large current startup of capacitive loads is supported.
◆Automatic recognition of battery voltage is supported.
◆LED fault indicators and an LCD screen which can display abnormality information
help users to quickly identify system faults.
◆Historical data storage function is available, and data can be stored for up to a year.
◆The controller is equipped with an LCD screen with which users can not only check
device operating data and statuses, but also modify controller parameters.
◆The controller supports standard Modbus protocol, fulfilling the communication needs
of various occasions.
◆The controller employs a built-in over-temperature protection mechanism. When
temperature surpasses the set value, the charging current will decline in linear
proportion to the temperature so as to curb the temperature rise of the controller,
effectively keeping the controller from being damaged by overheat.
◆Featuring a temperature compensation function, the controller can automatically adjust
charging and discharging parameters in order to extend the battery's service life.

◆TVS lighting protection
1.3 Exterior and Interfaces
Fig. 1-1 Product appearance and interfaces
No.
Item
No.
Item
○
1
Charging indicator
○
10
Battery "+" interface
○
2
Battery indicator
○
11
Battery "-" interface
○
3
Load indicator
○
12
Load "+" interface
No.
Definition
○
1
Transmitting terminal TX
○
2
Receiving terminal RX
○
3
Power supply grounding /Signal grounding
○
4
Power supply grounding /Signal grounding
○
5
Power supply positive
○
6
Power supply positive
○
3
○
4
○
9
○
10
○
11
○
12
○
13
○
6
○
5
○
2
○
1
○
8
○
14
○
15
○
7

○
4
Abnormality indicator
○
13
Load "-" interface
○
5
LCD screen
○
14
External temperature
sampling interface
○
6
Operating keys
○
15
RS232 communication
interface
○
7
Installation hole
○
8
Solar panel "+"
interface
○
9
Solar panel "-"
interface
1.4 Introduction to Maximum Power Point Tracking Technology
Maximum Power Point Tracking (MPPT) is an advanced charging technology that
enables the solar panel to output more power by adjusting the electric module's
operating status. Due to the nonlinearity of solar arrays, there exists a maximum
energy output point (maximum power point) on their curves. Unable to
continuously lock onto this point to charge the battery, conventional controllers
(employing switching and PWM charging technologies) can't get the most of the
power from the solar panel. But a solar charge controller featuring MPPT
technology can continuously track arrays' maximum power point so as to get the
maximum amount of power to charge the battery.
Take a 12V system as an example. As the solar panel's peak voltage (Vpp) is
approximately 17V while the battery's voltage is around 12V, when charging with a
conventional charge controller, the solar panel's voltage will stay at around 12V,
failing to deliver the maximum power. However, the MPPT controller can
overcome the problem by adjusting the solar panel's input voltage and current in
real time, realizing a maximum input power.
Compared with conventional PWM controllers, the MPPT controller can make the
most of the solar panel's max. power and therefore provide larger charging current.
Generally speaking, the latter can raise the energy utilization ratio by 15% to 20%
in contrast with the former.

PWM充电
U(V)
I(A) P(W)
VP曲线
VI曲线
94.5
81.0
67.5
54.0
27.0
40.5
13.5
0.0
19.6
16.814.011.28.4
5.6
2.80.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
MPPT点
Fig. 1-2 Solar panel output characteristic curve
Meanwhile, due to changing ambient temperature and illumination conditions, the
max. power point varies frequently, and our MPPT controller can adjust parameter
settings according to the environmental conditions in real time, so as to always keep
the system close to the max. operating point. The whole process is entirely
automatic without the need of human intervention.
Fig. 1-3 Relation between solar panel output characteristics and illumination
光照降低，电流减小
光照降低，开路电压减小
U(V)
I(A)
P (W)
I (A)
Current decreases with dwindling light
Open-circuit voltage decreases with dwindling light
VP curve
VI curve
MPPT point
PWM charging

Fig. 1-4 Relation between solar panel output characteristics and temperature
1.5 Charging Stages Introduction
As one of the charging stages, MPPT can not be used alone, but has to be used
together with boost charging, floating charging, equalizing charging, etc. to
complete charging the battery. A complete charging process includes: fast
charging, sustaining charging and floating charging. The charging curve is as
shown below:
20℃
50℃
70℃
60℃
40℃
30℃
太
阳
板
温
度
I(A)
U(V)
温度降低，电流不变，
功率增大
温度升高，开路电压减小
With temperature dropping, current
stays stable and power increases
Solar panel temperature
Open-circuit voltage decreases with rising temperature

Fig. 1-5 Battery charging stages diagram
a) Fast charging
At the fast charging stage, as the battery voltage has not reached the set value of full voltage (i.e. equalizing/ boost
voltage) yet, the controller will perform MPPT charging on the battery with the maximum solar power. When the
battery voltage reaches the preset value, constant voltage charging will begin.
b) Sustaining charging
When the battery voltage reaches the set value of sustaining voltage, the controller
will switch to constant voltage charging. In this process, no MPPT charging will be
performed, and meanwhile the charging current will also gradually decrease. The
sustaining charging stage itself consists of two sub-stages, i.e. equalizing charging
and boost charging, the two of which are not carried out in a repeated manner, with
the former getting activated once every 30 days.
Boost charging
By default, boost charging generally lasts for 2h, but users can adjust preset values
of duration and boost voltage point according to the actual needs. When the
Battery voltage
Battery voltage
Fast
charging
Sustaining
charging
Floating
charging
Max.
current
Duration: 2h
(range: 10 to
600min)
Cumulative
time: 3h
Time
Time
Equalizing charging voltage
Boost charging voltage
Floating charging voltage
Charging return voltage