Dometic Solar Controller

1.1 GENERAL DESCRIPTION

A solar controller, also known as a charge controller or regulator, is an essential component of your photovoltaic solar system. The
controller maintains the life of the battery by protecting it from overcharging and maximizes the power usage from your solar panel.
When your battery has reached a 100% state of charge, the controller prevents overcharging by limiting the current flowing into the
batteries from your solar array.
The SC-DB-MPPT uses maximum power point tracking (MPPT) technology and a unique four stage charging system that includes an
optional equalization setting to charge and protect your battery bank. In addition, the SC-DB-MPPT has the ability to trickle charge
a secondary battery. The intended use of this feature is to maintain the RV starter battery while it is parked for long periods of time.
The 30 A and 40 A MPPT controllers are intended for use at 12 or 24 VDC nominal system voltage, and are rated for a maximum continuous
DC charge current of 30 A and 40 A respectively. The SC-DB-MPPT is suitable for use with lead acid batteries (flooded, GEL, or
AGM), as well as lithium iron phosphate (LiFePO4) batteries that are supplied with a battery management system (BMS).

1.2 FEATURES

1.3 WHAT’S INCLUDED

1.4 DIMENSIONS

The dimensioned drawing is not to scale. Refer to the appendix for the mounting template.

               

 

1.5 REGULATORY INFORMATION

Certified to CSA Std. C22.2 No. 107.1

1.6 SPECIFICATIONS

     

1.7 MAXIMUM POWER POINT TRACKING (MPPT) TECHNOLOGY           

Maximum power point tracking (MPPT) is an advanced charging technology that efficiently harvests power from solar panels in all
conditions. This is achieved by continuously tracking the I-V curve of the solar array and modifying operating conditions to maximize
output power. The graph below shows the MPPT point compared to a traditional PWM charger, which always runs the solar array at
a voltage close to the battery voltage.

Due to differences in ambient temperature and light conditions, the maximum power point often changes. The MPPT controller can
adjust parameters according to quickly changing conditions to keep the system near to its maximum working point. The whole process
is fully automatic and does not require any adjustments or interference by users. The graphs below show how the IV curve changes
with varying sunlight conditions, and varying temperatures.

In partially shaded conditions there can also be multiple peaks in the P-V curve that can confuse an MPPT algorithm. Shown in the
diagram below is a series string of solar panels.

         

The corresponding graph below shows local maximum power points (LMPP) and the global maximum power point (GMPP) that will
result in maximum energy transfer. The SC-DB-MPPT controllers have a smart algorithm that will always choose the correct peak.

The SC-DB-MPPT controller has an MPPT efficiency of up to 99.9 %, meaning there is no wasted potential from your solar panels.                                                                  

1.8 SYSTEM VOLTAGE AND CURRENT

The 30 A and 40 A MPPT controllers are intended for use at 12 or 24 VDC nominal system voltage and are rated for a maximum continuous
DC charge current of 30 A and 40 A respectively, and maximum solar input voltage of 96 Voc.
Per the National Electric Code (NEC) article 690.7 and 690.8, solar panel nameplate ratings at Standard Test Conditions (STC) must
be multiplied by required values (typically 1.25 for both voltage and current) to obtain the maximum voltage and continuous current
available from the panel.
The voltage and current ratings of all equipment connected to solar panels must be capable of accepting the voltage and current levels
available from solar panels installed in the field.

1.9 CURRENT DERATING

The SC-DB-MPPT constantly monitors the internal temperature to ensure it does not exceed temperature limits. In applications that
require full output current in high ambient temperatures, the solar controller starts limiting the current delivered to the battery to keep
the internal temperature within the required specifications.

1.10 TEMPERATURE COMPENSATION

The SC-DB-MPPT has the ability to perform temperature compensation. This feature extends the life of the battery by preventing
overcharging in warm temperatures, and undercharging in cold temperatures. Temperature compensation is not required for lithium
batteries. In order to utilize the temperature compensation feature, the SC-DB-MPPT must be paired with an RV-C device that reports
the battery temperature, such as the PowerTrak Smart Shunt (sold separately). The temperature compensation coefficient is -24 mv/°C
by default, and can be adjusted using the PowerTrak Display (sold separately).

1.11 BATTERY TYPE

The SC-DB-MPPT controller is suitable for use with lead acid batteries (vented, GEL, or AGM) as well as lithium iron phosphate (LiFePO4)
batteries that are supplied with a battery management system (BMS).
A custom profile in the settings allows creating a specific battery profile by programming and adjusting various charging parameters
such as the charging voltage set points.

1.12 BATTERY CHARGING STAGES

Maximum power point tracking is used to charge the batteries with the highest current possible, but this is only part of the equation.
The multistage battery charger can use up to four different charging stages to help monitor and keep the batteries healthy.

These stages include bulk, absorption, float and, for some types of batteries, equalization.

1.12.1 FIRST STAGE: BULK

In the bulk stage, the battery voltage has not yet reached the set value of full charge voltage (i.e. equalizing/boost charge voltage) and
the controller will perform MPPT charging, which will provide maximum solar energy to charge the battery. When the battery voltage
reaches the absorption voltage, the second stage will start.

1.12.2 SECOND STAGE: ABSORPTION

When the battery voltage reaches the absorption voltage, the controller will perform constant voltage charging. This is no longer MPPT
charging, and the charging current will gradually decrease with time.

1.12.3 THIRD STAGE: FLOAT

After the absorption stage, the controller will reduce the charge current to a small amount in order to reduce sulfates on the battery
plates or to allow a lithium battery to balance its cells. If the load exceeds this small current the battery voltage will start to decrease
until it reaches the recharge voltage. When the battery voltage falls below the recharge voltage, the controller will switch back to
bulk charging.

1.12.4 FOURTH STAGE: EQUALIZATION

Certain battery types benefit from equalization charging to stir up stratified electrolyte and to reverse any battery plate sulfation that
may have occurred. The equalization charge increases the battery voltage above a standard voltage, causing vaporization of battery
electrolyte. By default, this happens every 30 days for flooded batteries.

1.12.5 RECHARGE

After the battery is completely charged the charging cycle completes and the battery is allowed to slowly discharge until it reaches
the charge return voltage at which point a new charge cycle is initiated.

1.12.6 CHARGE PARAMETERS FOR VARIOUS BATTERY TYPES

If the manufacturer of your third-party battery recommends charging parameters that differ from the parameters in the table below,
select the custom battery option to manually set your charging profile.

2.1 CHOOSING AN INSTALLATION LOCATION

The SC-DB-MPPT controller is designed to be mounted flush against a wall, out of the
way, but easily visible with an unobstructed view of the status LEDs. The SC-DB-MPPT
must be installed in a location that meets the following requirements. 
• The controller must be mounted as close to the battery as possible.
• The controller must be mounted vertically on a non-flammable surface with power
terminals facing downward to optimize cooling of the unit by natural convection.
• The controller must be indoors, protected from the weather.
• The controller must be mounted with at least 6 inches of air gap above and below
for the natural convection to be effective.
Solar connections should connect directly to the controller. Positive and negative battery
connections must connect directly from the controller to the batteries. Use of a positive
or negative distribution bus is allowed between the controller and battery as long as it is
properly sized, electrically safe and an adequate wire size is maintained.

2.2 REQUIRED TOOLS AND MATERIALS

• Phillips screwdriver
• Drill
• 7/64” drill bit
• No tools needed for wiring connections (tool-less lever terminals)

3.1 MOUNTING THE CONTROLLER

Use the SC-DB-MPPT mounting template located in the appendix to mark out all four mounting holes in the desired mounting location.
Drill four pilot holes with a 7/64” drill bit at the marked locations. Insert the screws in the top two mounting holes, without fully
tightening them. Align the top two mounting holes of the controller with the pre-fixed screws and hang the controller on the wall.
Tighten the top two screws, then insert the bottom two screws and tighten them.

3.2 INSTALLATION OF THE SOLAR PANELS

Install your solar array, and cover panels with opaque material until all wiring is complete. If your SC-DB-MPPT was purchased as part
of a solar power kit, follow the installation guide provided. Otherwise, follow manufacturer’s instructions for solar panel mounting
and wiring.

3.3 WIRE TYPE AND GAUGE

If this SC-DB-MPPT was purchased as part of a solar power kit, appropriate wire type, gauge, and length is provided. If the SC-DB-MPPT
was purchased separately, follow the instructions included here.
Wire type is recommended to be a stranded copper. Note, any external wiring should be UV-resistant, outdoor rated wire. Wire gauge
should be able to sustain rated current and minimize voltage drop.

3.3.1 WIRE GAUGE & FUSE SIZING

The table below outlines the suggested minimum wire gauge and maximum fuse size with a 25 ft maximum length from the solar array
to the battery bank. The wire length between the battery bank and the solar controller should be maximum 10ft.

3.3.2 WIRE STRIP LENGTH

The wire stripping length for the push-in cage clamps is approximately 11-13 mm (0.5 in).

3.4 SOLAR CONTROLLER WIRING

1.    Route the wires from the solar array and the batteries to the location of the SC-DB-MPPT controller.

2.    Remove the cover from the solar controller. Refer to the wiring diagram above or terminal ID label on the inside of the removable
cover for connection details.

The wires will be connected with the push-in cage clamps. To do so, lift the orange lever until it is perpendicular with
the terminals and insert the wire into the terminal. Push in the wire as far as the terminal will allow. Press down on the
orange lever to lock the wire in place. Ensure the wire is securely inserted by pulling back firmly on the wire.

3.    Connect the main battery to the B1+ and B1- terminals as shown in the terminal diagram. The main battery alone can power
on the controller.
4.    Connect PV to the PV+ and PV- terminals as shown in the terminal diagram. PV alone can power on the controller.
5.    Connect the secondary battery to the B2+ and B2- terminals as shown in the terminal diagram (optional). The secondary battery
alone will not power on the controller.

The controller will not work unless there is a battery connected to the battery terminals with at least 8 V or energized
solar panels connected.

 CAUTION: Risk of Electric Shock: When the photovoltaic array is exposed to light, it supplies a DC voltage to this equipment.

CAUTION: Internal Temperature Compensation: Risk of fire, ensure the length of wire between the controller and the batteries
is less than 3m.

6.    Turn on breakers or connect to batteries in the order of battery 1, battery 2, and PV. The controller will power up and the green
LED will start flashing. Remove the opaque material from the solar array.

The negative solar array and battery wiring must be connected directly to the controller for proper operation. Do not
connect the negative solar array or negative battery controller wiring to the chassis of the vehicle.

WARNING: This unit is not provided with a GFDI device. This charge controller must be used with an external GFDI device as
required by Article 690 of the National Electric Code for the installation location.

3.5 RV-C CONNECTION

The RV-C connector is a standard RV-C Molex connector with the following pinout.

Use this to connect the SC-DB-MPPT to the RV-C bus, and other RV-C devices, like the PowerTrak Display (sold separately).

4.1 POWER ON

The SC-DB-MPPT controller will automatically power on when it is connected to the battery or energized solar panels.
IMPORTANT: You must set the battery type on the SC-DB-MPPT before you begin to use the controller (follow steps in section
4.4.5). The default battery setting is for AGM batteries.

4.2 LED INDICATORS

The SC-DB-MPPT controller has three LED indicators that display the status of the controller.

4.3 INSTANCES

The DIP switches on the SC-DB-MPPT are for setting the controller instances. This is how devices are distinguished on the RV-C bus.
Refer to the table below or the instance ID label on the inside of the removable cover to set the instances. If you have multiple solar
controllers in your system, make sure they each have a unique instance ID.
INSTANCE ID DIP 1 DIP 2 DIP

4.4 POWERTRAK DISPLAY

The PowerTrak Display is the remote required for controlling the settings on the SC-DB-MPPT and viewing system details. The SCDB-
MPPT and the PowerTrak Display (sold separately) are compatible with the Dometic PowerTrak system. The PowerTrak system
technology ensures compatible devices work together to optimize power flow and efficiency. This section will outline connection
and basic operation of the PowerTrak Display. For more details, please use the QR code below to access the user manual for the
PowerTrak Display.

Scan the QR code to access the PowerTrak Display user manual.

4.4.1 DEVICE CONNECTION

The PowerTrak devices are connected via RV-C harnessing (sold separately). The wiring diagram below shows the connection details
for a system with a SC-DB-MPPT and a PowerTrak Display.

Other examples of PowerTrak compatible devices include the Advanced Inverter/Charger, and the Advanced Lithium Batteries. A
wiring diagram for an example system including these devices is shown below.

If your power system contains other RV-C compatible devices, you may require a different combination of RV-C harnesses. Please
refer to our RV-C Configurator through the QR code below to determine which cables are required for your system. Contact technical
support at 1-866-247-6527 if you are unsure about the RV-C requirements for your system.

4.4.2 DISPLAY POWER-UP

The PowerTrak Display is powered from the SC-DB-MPPT controller via the RV-C cable, and automatically turns on when connected to
the system. A message is displayed that a search for connected devices is in progress.

Confirm the SC-DB-MPPT is loaded on the screen, along with any other components that are in your system.

4.4.3 OPENING THE DISPLAY SETTINGS

4.4.4 SWITCHING THROUGH THE SETTINGS

4.4.5 SOLAR SETTINGS

1.    Press the “Solar Settings” button on the settings screen.
2.    Press the “B1 Battery Type” and “B2 Battery Type” buttons to set the battery type for the B1 (main) battery and B2 (trickle charge)
battery in your system.
3.    Press the “B1 Capacity” and “B2 Capacity” buttons to set the capacity of the B1 (main) battery and B2 (trickle charge) battery in
your system.
4.    Press the “Force Charge” button to change the charge state on the B1 (main) battery or B2 (trickle charge) battery in your system.
5.    If you selected “Custom” batteries for B1 and/or B2, solar settings pages 4-13 will be visible. The values on these pages must be
set if you have a custom battery bank set up. Refer to the battery manufacturers recommendations when setting these values.

4.5 USING THE CONNECT APP

4.5.1 CONNECTING THE POWERTRAK DISPLAY TO THE APP

1.    Use the + button to pair the PowerTrak Display with the app.

2.    A message will be displayed asking to place the devices to be paired close to each other for first time set up. Press the OK button.

3.    After pairing the connected devices are listed. If the PowerTrak Display is connected to the SC-DB-MPPT and has been paired with
the app correctly, the SC-DB-MPPT should be listed as a connected device. If necessary, press the refresh button in the bottom
left corner to reload the list.

4.5.2 ACCESSING THE SOLAR SETTINGS

1.    Press the CONNECT button that corresponds to the SC-DB-MPPT.
2.    The main status screen for the SC-DB-MPPT will be displayed. The history and details tabs can be pressed to display more details
about the controller.

How to Read this Section

Troubleshooting Problems is split into two sub-sections, grouped by symptoms involving key components. Components considered
irrelevant in a diagnosis are denoted ‘Not Applicable’ (N/A). A multimeter or voltmeter may be required for some procedures listed.
It is imperative all electrical precautions stated in the Warning Section and outlined in the Installation Section are followed. Even if it
appears the system is not functioning, it should be treated as a fully functioning system generating live power.

6.1 PROBLEMS WITH VOLTAGE

Voltage Reading: Inaccurate

Time of Day: Daytime/Nighttime

Possible Causes:

• Excessive voltage drop from batteries to controller due to loose connections, small wire gauge, too long of wire length, or a
combination of these.

How to tell:

1.    Check the voltage at the controller battery terminals with a voltmeter and compare with the voltage reading at the battery terminals.
2.    If there is a voltage discrepancy of more than 0.5 V, there is an excessive voltage drop.

Remedy:

Check all connections from the controller to the battery including checking for correct wire polarity. Check that all connections are clean,
tight, and secure. Shorten the distance from the controller to battery or obtain larger gauge wire.

6.2 PROBLEMS WITH CURRENT

Current Reading: Less than expected

Time of Day: Daytime, clear sunny skies

Possible Cause:

• Current is being limited as per normal operation due to over temperature, or charging stage.
• Incorrect series/parallel solar panel configuration and/or wiring connections and/or wire gauge (for multiple panel systems).
• Dirty or shaded panel or lack of sun.
• Blown diode in solar panel when two or more panels are connected in parallel.
How to tell:
1.    Battery voltage is at or very near the boost or float charge setting.
2.    The device temperature is to high.
3.    Check that the panels and batteries are configured correctly. Check all wiring connections.
4.    Panels look dirty, overhead object is shading panels or it is an overcast day in which a shadow cannot be cast.

5.    Disconnect one or both array wires from the controller. Take a voltage reading between the positive and negative array wire.
Compare to nameplate rating. If you have more than one solar panel, you will need to conduct this test between the positive
and negative terminals of each panel junction box with either the positive or the negative wires disconnected from the terminal.
Remedy:
1.    Reconnect in correct configuration. Tighten all connections. Check wire gauge and length of wire run. Refer to suggested minimum
wire gauge in section 3.
2.    Clean panels, clear obstruction or wait for conditions to clear.
3.    If the open circuit voltage of a non-connected solar panel is lower than the manufacturer’s specifications, the panel may be faulty.
Check for blown diodes in the solar panel junction box, which may be shorting the power output of the panel.

8.1 MOUNTING TEMPLATE