Sun21 MAX-M2024 User manual

MPPT Solar Charge Controller
User Manual
Models:
MAX-M2024
MAX-M3024
MAX-M4024

Important Safety Instructions
Please save this manualfor future review.
This manualcontainssafety,installationandoperationfor MaximumPower Point
Tracking (MPPT) MAX series controller ("the controller" as referred to in this manual).
General Safety Information
Read carefullyall the instructionsand warningsin the manual before installation.
No user serviceablecomponentsinsidethe controller.DO NOT disassembleor
attemptto repair the controller.
Mount the controllerindoors.Prevent exposure to the elementsand do not allow
water to enter the controller.
Install the controllerin awell ventilated-place.The controller’s heat sink may
becomevery hot during operation.
It is suggestedto installappropriateexternal fuses/breakers.
Make sure to switch off all PV array connections and the battery fuse/breakers
before controller installationand adjustment.
Power connectionsmust remaintightto avoidexcessiveheatingfrom loose
connection.

CONTENTS
1. General Information........................................................................1
1.1 Overview..............................................1
1.2 Characteristics.........................................2
1.3 Designationsof Controller Models .......2
1.4 Maximum Power Point Tracking Technology ...............2
1.5 Battery Charging Stage .................................4
2. Installation Instructions .................................................................7
2.1 General InstallationNotes ...............................7
2.2 PV Array Requirements .................................7
2.3 Wire Size .............................................9
2.4 Mounting.............................................10
3. Operation.......................................................................................14
3.1 Button ...............................................14
3.2 Interface .............................................14
3.3Setting...............................................16
4. Protections, Troubleshooting and Maintenance ........................20
4.1 Protection............................................20
4.2 Troubleshooting.......................................21
4.3 Maintenance .........................................21
5. Technical Specifications..............................................................23
Annex I Conversion Efficiency Curves ...........................................25
Annex II Dimensions ........................................................................28

1
1. General Information
1.1 Overview
Based on common negative design and advanced MPPT control algorithm, with LCD
displaying running status, this product is artistic, economical and practical. Improving
the MPPT control algorithm further, it can minimize the maximum power point loss
rate and loss time, quickly track the maximum power point of the PV array and obtain
the maximum energy from solar modules under any conditions; and can increase the
ratio of energy utilization in the solar system by 10%-30% compared with a PWM
charging method. The limitation function of the charging power and current and
reducing charging power function automatic improve the stability which works even
connecting oversize PV modules and in high temperature, and increase the
professional protection chip for the communication port, further improving the
reliabilityand meeting the differentapplicationrequirements.
With the adaptive three-stage charging mode based on a digital control circuit, the
series controllers can effectively prolong the life-cycle of batteries, significantly
improve the system performance and support all-around electronic protection
functions, including overcharging and over discharging protection to minimize
damages to components of the system caused by incorrect installation or system
failure at the utmost, and effectively ensure safer and more reliable operation of the
solar power supply system for a longer service time. This modular solar controller can
be widely used for different applications, e.g., Communication base stations,
householdsystems,and field monitoring,etc.
Features：
Advanced MPPT technology, withefficiencyno lessthan 99.5%
Ultra-fasttrackingspeed and guaranteed trackingefficiency
Advanced MPPT controlalgorithm to minimize the maximum power point loss
rate and losstime
WideMPP operatingvoltagerange
High quality components,perfectingsystem performance,with maximum
conversionefficiencyof 98%
Accurate recognitionand tracking of multiple-peaksmaximum power point
Internationalfamousbrandsof ST and IR's componentsof high qualityand low
failurerate are used, which can ensure the product’s servicelife
Chargingpower and currentlimitationfunction
Compatiblewith lead-acidandlithium-ionbatteries
Battery temperaturecompensationfunction
Real-timeenergy statisticsfunction
Overheating power reduction function
Multipleloadwork modes
The communication port adopts professionalprotection chip, whichcan provide
5VDC power supply,and has over-current and short-circuit protection.

Full-loadoperationwithout any drop in capacitywithinthe range of working
environment temperature
Extensive electronic protection
1.2 Characteristics
❶SELECT button ❻RS485 communicationinterface
❷RTS★Interface ❼MountingHole Φ5mm
❸PV Terminals ❽ENTER button
❹Battery Terminals ❾LCD
❺LoadTerminals
★If the temperature sensor is short-circuited or damaged,the controllerwill
chargeor dischargeat the defaulttemperature settingof 25 ºC.
1.4 Maximum Power Point Tracking Technology
Due to the nonlinear characteristics of solar array, there is a maximumenergy output
point (Max Power Point) on its curve.Traditionalcontrollers,with switch charging
technology and PWM chargingtechnology, can’t charge the batteryat the maximum
power point, so can’t harvest the maximum energy availablefrom PV array,but the
Figure 1 Product Characteristics
2

solar charge controller with Maximum Power Point Tracking(MPPT) Technology can
lock on the point to harvestthe maximum energy and deliver it to the battery.
The MPPT algorithm of our company continuouslycompares and adjuststhe
operating pointsto attempt to locate the maximum power point of the array.The
tracking process is fully automatic and does not need user adjustment.
As the Figure1-2, the curveis also the characteristiccurve of the array, the MPPT
technology will ‘boost’ the batterychargecurrentthrough trackingthe MPP. Assuming
100% conversionefficiencyof the solar system, in that way, the followingformula is
established:
Input power (PPV)= Output power (PBat)
Input voltage (VMpp) *input current (IPV) =Battery voltage (VBat) *battery current (IBat)
Normally, the VMpp is alwayshigher than VBat, Due to the principleof conservationof
energy, the IBat is alwayshigher than IPV.The greater the discrepancybetween VMpp
&VBat, the greater the discrepancybetween IPV& IBat. The greater the discrepancy
between array and battery, the bigger reductionof the conversion efficiency of the
system, thus the controller’s conversion efficiency is particularlyimportantin the PV
system.
Figure 1-2 is the maximumpower pointcurve,the shaded area is chargingrange of
traditional solar charge controller (PWM ChargingMode), it can obviouslydiagnose
that the MPPT modecan improvethe usageof the solar energy resource.According
to our test, the MPPT controller canraise 20%-30%efficiencycomparedto the PWM
controller.(Value may be fluctuantdue to the influenceof the ambientcircumstance
and energy loss.)
Figure 1-2 MaximumPower Point Curve
3

In actual application, as shading from cloud, tree and snow, the panel maybe appear
Multi-MPP, but in actually there is only one real Maximum Power Point. As the below
Figure1-3 shows:
Figure 1-3 Mutil-MPPCurve
If the programworks improperly after appearingMulti-MPP, the systemwill not work
on the real max power point, whichmay waste most solar energy resources and
seriously affectthe normal operationof the system. The typical MPPT algorithm,
designed by our company,can trackthe real MPP quicklyand accurately,improvethe
utilization rate of the array and avoid the wasteof resources.
1.5 Battery Charging Stage
The controller has a 3 stages batterychargingalgorithm(BulkCharging,Constant
Chargingand Float Charging)for rapid,efficient,and safe battery charging.
Figure 1-4 BatterychangingstageCurve
A) Bulk Charging
4

In this stage, the batteryvoltage has not yet reached constant voltage(Equalize or
Boost Voltage),the controller operates in constantcurrent mode, deliveringits
maximumcurrent to the batteries (MPPTCharging).
B) ConstantCharging
Whenthe batteryvoltagereaches the constantvoltage setpoint,the controller will start
to operate in constant charging mode, this process is no longer MPPT charging, and
in the meantimethe charging current will drop gradually,the processis not the MPPT
charging.The ConstantCharginghas 2 stages, equalize and boost.These two stages
are not carriedout constantly in a fullcharge process to avoidtoo much gas
precipitationor overheatingof battery.
Boost Charging
The Boost stagemaintain 2 hours in default,user can adjust the constanttime and
preset value of boost voltageaccordingto demand.
The stage is used to prevent heatingand excessivebatterygassing.
Equalize Charging
WARNING:ExplosiveRisk!
Equalizingflooded battery wouldproduce explosive gases, so well
ventilationof batterybox is recommended.
CAUTION: Equipment damage!
Equalizationmay increase batteryvoltage to the level that damages
sensitiveDC loads.Verify that all load allowableinput voltages are 11%
greater than the equalizingchargingset pointvoltage.
CAUTION: Equipment damage!
Over-chargingand excessivegas precipitationmay damagethe battery
plates and activatematerial sheddingon them. Too high an equalizing
charge or for too longmay causedamage.
Please carefully review the specificrequirementsof the batteryused in the system.
Some types of batteriesbenefitfrom equalizingcharge on a regular basis,whichis
able to stir electrolyte,balancebatteryvoltageand accomplish chemicalreaction.
Equalizingcharge increases battery voltage, higher than the standard complement
voltage, whichgasifiesthe batteryelectrolyte.
The controller will equalize the batteryon 28th each month.The constantequalization
period is 0~180minutes.If the equalization isn’t accomplished in one-time,the
equalizationrechargetime will be accumulateduntil the set timeis finished.Equalize
charge and boost charge are not carried out constantlyin a full charge processto
avoidtoo much gas precipitationor overheatingof battery.
NOTE:
1) Due to the influenceof ambientcircumstanceor load working, the battery
voltage can’t be steady in constantvoltage,controllerwill accumulateand
calculate the time of constantvoltage working. When the accumulatedtime
reach to 3 hours, the chargingmode will turn to Float Charging.
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6
2) If the controllertime is not adjusted, the controllerwill equalizecharge
battery once every month followingthe inner time.
C) Float Charging
After the Constantvoltage stage, the controller will reduce chargingcurrent to Float
Voltage setpoint. This stage will have no more chemicalreactionsand all the charge
current transformsintoheat and gas at this time. Then the controller reduces the
voltage to the floatingstage, chargingwith a smaller voltageand current.It will reduce
the temperatureof the battery and prevent the gassing and charging the battery
slightly at the same time.The purposeof Float stage is to offset the power
consumption caused by self consumptionand smallloads in the whole system,while
maintainingfull batterystoragecapacity.
In Floatchargingstage,loadsare ableto obtain almostall power from solarpanel.If
loads exceed the power, the controller will no longer be able to maintainbattery
voltage in Float charging stage. If the batteryvoltageremainsbelow the Recharge
Voltage, the systemwill leave Floatcharging stage and returnto Bulk charging stage.

7
2. InstallationInstructions
2.1 General InstallationNotes
Please read the entire installationinstructions to get familiarwith the installation
steps before installation.
Be very carefulwhen installingthe batteries,especially flooded lead-acid battery.
Please wear eye protection, and have fresh water availableto wash and clean any
contact with batteryacid.
Keep the batteryaway from any metal objects,which may cause short circuit of the
battery.
Explosive batterygases may come out from the battery during charging, so make
sure ventilationcondition is good.
Ventilationis highly recommendedif mounted in an enclosure. Never installthe
controller in a sealed enclosurewith flooded batteries!Batteryfumesfrom vented
batteries will corrodeand destroy thecontroller circuits.
Loose power connections and corroded wires may result in high heat that can melt
wire insulation, burn surrounding materials, or even cause fire. Ensure tight
connections and use cable clamps to secure cables and prevent them from swaying
in mobileapplications.
Lead-acidbatteryand lithiumbattery are recommended,other kinds pleaserefer to
the batterymanufacturer.
Battery connection may be wired to one battery or a bank of batteries. The following
instructions refer to a singular battery, but it is implied that the battery connection
can be madeto either one batteryor a group of batteries in a batterybank.
Multiple same models of controllers can be installed in parallel on the same battery
bank to achieve higher charging current. Each controller must have its own solar
module(s).
Select the system cables accordingto 5A/mm2or less currentdensityin accordance
with Article690 of the NationalElectrical Code, NFPA 70.
2.2 PV Array Requirements
(1) Serial connection (string)of PV modules
As the core componentof PV system,controller could be suitable for varioustypes of
PV modulesand maximizeconverting solar energy into electrical energy. Accordingto
the open circuitvoltage(Voc) and the maximum power point voltage (VMpp) of the
MPPT controller,the series numberof differenttypes PV modulescan be calculated.
The below table is for reference only.

MAX-M2024/3024/4024:
Sy
stem
voltage
36 cell
Voc＜23V 48 cell Voc＜31V 54 cell Voc＜34V 60 cell Voc＜38V
Max. Best
Max.
Best Max. Best Max. Best
12V 4 2 2 1 2 1 2 1
24V 4 3 2 2 2 2 2 2
Sy
stem
voltage
72 cell Voc＜46V 96 cell Voc＜62V Thin-Fil
m
Module
Voc＞80V
Max. Best Max. Best
12V 2 1 1 1 1
24V 2 1 1 1 1
NOTE:The aboveparametervalues are calculatedunder standardtest conditions
(STC (Standard Test Condition)：Irradiance1000W/m2，ModuleTemperature25℃，
Air Mass1.5.)
(2) MaximumPV arraypower
The MPPT controller has the function of current/power-limiting, that is, during the
charging process, when the charging current or power exceeds the rated charging
current or power, the controller will automatically limit the charging current or power to
the rated charging current or power, which can effectively protect the charging parts of
controller, and prevent damages to the controller due to the connection of some over-
specificationPV modules.The actual operationof PV array is as follows:
Condition1:
Actual charging power of PV array ≤Rated charging power of controller
Condition2:
Actual charging current of PV array ≤Rated chargingcurrentofcontroller
When the controller operates under “Condition 1”or“ Condition 2”, it will carry out the
charging as per the actual current or power; at this time, the controller can work at the
maximumpower point of PV array.
WARNING:Whenthe power of PV is not greater than the rated charging
power, but the maximumopen-circuitvoltageof PV array is more than
50(MAX12**)/96V(MAX24**)(at the lowestenvironmentaltemperature),
the controllermay be damaged.
Condition3:
Actual charging power of PV array＞Ratedcharging power of controller
Condition4:
Actual charging current of PV array＞Ratedchargingcurrentof controller
Whenthe controlleroperatesunder “Condition3”or“Condition4”，it will carry out the
charging as per the rated currentor power.
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WARNING:Whenthe power of PV moduleis greater than the rated
chargingpower,and the maximumopen-circuitvoltageof PV array ismore
than 96V (at the lowest environmentaltemperature), the controller may be
damaged.
According to “Peak Sun Hours diagram”, if the power of PV array exceeds the rated
charging power of controller, then the charging time as per the rated power will be
prolonged, so that more energy can be obtained for chargingthe battery.However, in
the practicalapplication,the maximum power of PV arrayshall be not greaterthan 1.5
x the ratedchargingpower of controller. If the maximumpower of PV array exceeds
the rated chargingpower of controller toomuch,it will not onlycause the waste of PV
modules, but also increasethe open-circuit voltageof PV array due to the influenceof
environmentaltemperature,which may make the probabilityof damageto the
controller rise. Therefore,it is very important to configurethe system reasonably.For
the recommendedmaximumpower of PV array for this controller, pleaserefer to the
table below:
Model
RatedCharge
Current
RatedCharge
Power
Max. PVArray
Power Max. PV
open
circuitvoltage
MAX
-M2024 20A 260W/12V
520W/24V 390W/12V 780W/24V 92V①
100V②
MAX
-M3024 30A 390W/12V
780W/24V 580W/12V 1170W/24V
MAX
-M4024 40A 520W/12V
1040W/24V 780W/12V 1560W/24V
①At 25℃environmenttemperature
②At minimumoperatingenvironmenttemperature
2.3 WireSize
The wiringand installationmethods must conform to all national and local electrical
code requirements.
PV Wire Size
Since PV array output can vary due to the PV module size, connection method or
sunlight angle, the minimum wire size can be calculated by the Isc＊of PV array.
Please refer to the value of Isc in the PV module specification. When PV modules
connect in series, the Isc is equal to aPV modules Isc. When PV modules connect in
parallel, the Isc is equal to the sum of the PV module’s Isc. The Isc of the PV array
must not exceed the controller’s maximum PV input current. Please refer to the table
as below:
NOTE: All PV modulesin a given arrayare assumedto be identical.
＊Isc=shortcircuitcurrent(amps)Voc=open circuitvoltage.
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Model Max. PV input current Max. PV wire size＊
MAX-M2024 20A 6mm2/10AWG
MAX-M3024 30A 10mm2/8AWG
MAX-M4024 40A 16mm2/6AWG
＊These are the maximumwire sizes that will fit the controller terminals.
CAUTION: When the PV modules connect in series, the open circuit
voltage of the PV array must not exceed 92Vat 25℃environment
temperature.
Battery and Load Wire Size
The batteryand load wire size must conform to the rated current, the reference size
as below:
Model Rated
charge
current
Rated
discharg
e
current
Batterywire
size Loadwire size
MAX-M2024 20A 20A 6mm2/10AWG 6mm2/10AWG
MAX-M3024 30A 30A 10mm2/8AWG 10mm2/8AWG
MAX-M4024 40A 40A 16mm2/6AWG 16mm2/6AWG
CAUTION: The wire size is only for reference. If there is a long distance between the
PV array and the controller or between the controller and the battery, larger wires can
be used to reducethe voltagedrop and improveperformance.
CAUTION: For the battery, the recommended wire will be selected
according to the conditions that its terminals are not connected to any
additionalinverter.
2.4 Mounting
WARNING:Risk of explosion!Never installthe controllerin a sealed
enclose with floodedbatteries! Do not install in a confinedarea where
battery gas canaccumulate.
WARNING: Risk of electricshock! When wiringthe solar modules, the PV
array can produceopen circuitvoltages in excess of 100V when in
sunlight.
10

11
CAUTION：Thecontrollerrequiresat least 150mmof clearanceabove
and below for proper air flow.Ventilation is highly recommendedif
mountedin an enclosure.
InstallationProcedure:
CAUTION: If the controlleris to be installedin an enclosedbox, it is
importantto ensure reliableheat dissipationthrough the box.
Figure 2-1 Mounting
Step 1: Determinationof InstallationLocation and Heat-dissipation Space
Determinationof installationlocation: The controller shall be installedin a placewith
sufficientair flow through the radiators of the controller and a minimumclearanceof
150 mm from the upper and lower edges of the controllerto ensure naturalthermal
convection.Please see Figure2-1: Mounting
11
Figure 2-2 Schematic of wiringdiagram

Connect one end of the remotetemperaturesensorcable
Step 2：Connect the system in the order of ❶battery ❷load❸PV array in
accordance with Figure 2-2,”Schematic Wiring Diagram” and disconnect the system in
the reverseorder❸❷❶.
CAUTION: Whilewiringthe controllerdo not closethe circuitbreakeror
fuse and make sure that the leadsof "+" and "-" polesare connected
correctly.
CAUTION: A fuse which currentis 1.25 to 2 timesthe rated currentof the
controller,must be installedon the batteryside with a distancefrom the
battery not greater than 150mm.
CAUTION: If the controller is to be used in an area with frequentlightning
strikes or unattendedarea, it mustbe installedan external surge arrester.
CAUTION: If an inverteris to be connectedto thesystem,connectthe
inverterdirectlyto the battery,not to the loadside of the controller.
Step 3：Grounding
MAX series is a common-negative controller, where all the negative terminals of PV
array, battery and load can be grounded simultaneously or any one of them will be
grounded. However, according to the practical application, all the negative terminals of
PV array, battery and load can also be ungrounded, but the grounding terminal on its
shell must be grounded, which may effectively shield the electromagnetic interference
from the outside, and prevent some electric shock to human body due to the
electrificationof theshell.
CAUTION: For common-negative system, such as motorhome, it is
recommended to use a common-negative controller; but if in the
common-negative system, some common-positive equipment are used,
and the positiveelectrodeis grounded, thecontroller may be damaged.
Step 4：Connectaccessories
Connect the remotetemperaturesensor cable (model:RTS-MAX1.0)
12
TemperatureSensor
（Model:TS-MAX1.0A）
Remote TemperatureSensor
Cable (Optional)
（Model:RTS-MAX1.0B）

to the interface③and place the other end close to the battery.
CAUTION: If the remote temperature sensor is not connected to the
controller,, the default setting for battery charging or discharging
temperatureis 25 °C withouttemperaturecompensation.
Connect the accessoriesfor RS485communication
Refer to chaper3.3“Setting”
CAUTION: If the remotetemperaturesensor is not connectedto the
controller,,the defaultsetting for batterycharging or discharging
temperatureis 25 °C withouttemperaturecompensation.
Step 5：Poweredon the controller
Closing the battery fuse will switch on the controller. Then check the status of the
battery indicator (the controller is operating normally when the indicator is lit in green).
Close the fuse and circuit breaker of the load and PV array. Then the system will be
operating in the preprogrammedmode.
CAUTION: If the controller is not operating properly or the battery indicator
on the controller shows an abnormality, please refer to 4.2
“Troubleshooting”.
13

3. Operation
3.1 Button
Mode Note
LoadON/OFF In load manual mode,it can turn the load On/Off of the load via
the “ENTER” button.
Clear Fault Press the “ENTER” button.
BrowsingMode Press the “SELECT” button.
Setting Mode
Press the “ENTER” button.and hold on 5s to enter the setting
mode
Press the “SELECT” button.to set the parameters,
Press the “ENTER” button. to confirm thesetting parameters or
exit the setting modeautomaticallyafter10s.
3.2 Interface
1）Icon
Item Icon Status
PV array Day
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Night
No charging
Charging
PV Voltage, Current,Power
Battery
Battery capacity,In Charging
Battery Voltage,Current, Temperature
Battery Type
Load
Load ON
Load OFF
Load Voltage, Current,Loadmode
2）FaultIndication
Status Icon Description
Batteryover
discharged Battery level shows empty,batteryframeblink, fault icon blink
Batteryover
voltage Battery level shows full,batteryframe blink,fault icon blink
Batteryover
temperature Battery level shows currentvalue, batteryframe blink, faulticon blink
Loadfailure Load overload①,Loadshortcircuit
①When load currentreaches1.02-1.05 times 1.05-1.25times, 1.25-1.35timesand
1.35-1.5timesmorethan nominalvalue, controller will automatically turn off loads in
50s, 30s,10sand 2s respectively.
15

3）Browseinterface
3.3 Setting
1)Clear the generatedenergy
Operation:
Step 1: Press the “ENTER” button and hold 5s under the PV power interface and
the valueis flashing.
Step 2: Press the “ENTER” button to clear the generated energy..
2)Switch the battery temperatureunit
Press the “ENTER” buttonand hold 5s under the batterytemperature interface.
3)Batterytype
①Batterytype
16

Item
Lead-acidbattery Lithium battery
1 Sealed(default) LiFePO4(4s/12V; 8s/24V)
2 Gel Li(NiCoMn)O2(3s/12V;6s/24V)
3 Flooded User(9～34V)
4User(9～17V/12V;18～34V/24V)
CAUTION: When the default battery type is selected, the battery voltage
control parameterswill be set by default and can’t be changed.To change
these parameters,select "User" battery type.
Operation:
Step1: Press the “ENTER” buttonand hold5s under the batteryvoltage interface.
Step2: Press the “SELECT” buttonwhen the batterytype interface is flashing.
Step3: Press the “ENTER” buttonto confirmthe battery type.
CAUTION：Pleaserefer to chapter③for the batterycontrol voltage, when
the batterytype is User.
②BatteryVoltageControl Parameters
Below parametersare in 12V system at 25 ºC, pleasedouble the values in 24V
system
Batterytype
Voltage Sealed Gel Flooded User
Over VoltageDisconnect
Voltage 16.0V 16.0V 16.0V 9～17V
ChargingLimitVoltage 15.0V 15.0V 15.0V 9～17V
Over VoltageReconnect
Voltage 15.0V 15.0V 15.0V 9～17V
EqualizeChargingVoltage 14.6V —— 14.8V 9～17V
Boost ChargingVoltage 14.4V 14.2V 14.6V 9～17V
Float ChargingVoltage 13.8V 13.8V 13.8V 9～17V
Boost Reconnect Charging
Voltage 13.2V 13.2V 13.2V 9～17V
Low VoltageReconnect
Voltage 12.6V 12.6V 12.6V 9～17V
Under VoltageWarning
Reconnect Voltage 12.2V 12.2V 12.2V 9～17V
Under VoltageWarning
Voltage 12.0V 12.0V 12.0V 9～17V
Low VoltageDisconnect
Voltage 11.1V 11.1V 11.1V 9～17V
DischargingLimit Voltage 10.6V 10.6V 10.6V 9～17V
EqualizeDuration 120min —— 120min 0～180min
Boost Duration 120min 120 min 120min 10～180min
17