CDT Solar

This installation guide is for experienced installers or dealers. It addresses the assembly of our standard CDT Solar RV panel connected to a 12-volt battery system. It does not list all possible variations of available solar panels.

Parts supplied: solar panel, 4 mounting braces with bolts

Parts needed: additional #10 wiring, battery connector, and fastener to RV roof or sealant

Required parts: Charge controller,

Recommended part:  Install a fuse between the controller and the battery to prevent electrical surge.

Tip:  The simplest connection point to the battery may be the porch light on/off switch.

Step 1:  Installing the charge controller (not included)

A solar charge controller is required.  It will prevent over-charging the battery and protects against cross-wiring of the panel. It also indicates the charging and battery status to prevent battery being drained.

Check your RV manual to see if a charge controller is already included in the electrical system.  If your RV does not include a built-in controller, two sizes charge controllers are available from CDT Solar.

CDT-C4  $25      4 Amp charge controller (#35004)– for up to 60W solar panels 12V.

CDT-C10 $50   10 Amp charge controller (#35010)– for up to 150W solar panels 12-24V.

Solar panel that is not 12/24V needs a MPPT controller.

Find a location to mount the controller as close to the battery as possible. Make sure the monitoring system and operation can be viewed easily.   Please read the full installation manual included with the controller (not included).

    Sizing chart for battery and solar panel with a controller:  

Solar Panel         5W   10W   20W            50W     100W   175W
Battery size(Ah)  20+   40+   80+            100+
Application       Battery maintenance         Over-night camping
Controller              -----------  4 Amp  --------- 10 Amp -- MPPT

Step 2:  Run the wiring (not included)

Estimate the length and size of wire needed for this installation.  
Wires must be run from the solar panel to the regulator and then to the battery.  
Do not connect the wires to the controller or the batteries yet.
Identify the polarity of the wires located on the battery and solar module (positive and negative) and use colored wires or tags to mark the wire ends.  
Contacting the leads of the regulator in reverse polarity, however brief, will blow the panel fuse/diode and may damage the controller.

Routing Power Cable through the Fridge Vent - Locate the refrigerator vent on the roof of the RV. Remove vent cover to gain access to the duct opening.  

Step 3:  Mount solar panel

4 mounting braces / brackets are included with the solar panel; Assemble the mounting brace securely to 4 corner of the solar panel.   See figure above for 5/10/20W panels.  (Please contact CDT solar if you would like to buy additional Z-brackest for added security.)

Note: The panel can also be mounted to the RV rooftop by using high strength sealant or glue instead of fasteners.

Fasten the mounting brace to the RV roof with proper size fasteners (not included).

Place the panel in a location that meets the following criteria:
• Select a location where the mounting surface is at least 1/2" thick and strong   enough to support mounting hardware, the solar panel and wind loads.
• Minimize the distance between the location of the solar module and the location where the power cable will enter the vehicle to connect to the battery.
• Place the panel for the lowest wind resistance on vehicles.
• Avoid internal wiring when selecting the spots for drilling the four mounting holes.
• Ensure obstacles, such as air conditioners, will not shade the solar module.
• Place module so that you have room to expand the current system if needed.
• Use the appropriate sealant as recommended by your RV Dealer to ensure a watertight installation.
•  Provide strain relief of the wiring to solar panel to avoid disconnection.

Step 4:  Connect the wiring to the battery and solar panel following these steps - Observe correct polarity at all times!

a. Connect the wiring to the solar panel, Red wire is positive (+); Black wire is negative (-)
b. Connect the wiring to the controller
c. Recommended: Connect the wiring to the fuse.  
    Size of the fuse amperage should be equal to the controller.  
    This will protect the battery and controller from short circuiting each other.
d. Connect the wiring to the battery.
e. Re-connect the battery terminals
f. Remove the paper covering the solar panel.  The panel should start charging the battery now and the controller will indicate the status of the solar panel and battery.


Calculate the daily minimum current loss of your RV battery by following these steps.

Step 1 -  Add all the “vampire” power usage of the appliances in your RV.   Including: microwave, smoke detector, clock, radio, TV, VCR, etc.      Enter the amount ->                                                                               x 24 hours
                                          =  Minimum Daily Current Draw   

Step 2 - Assume the battery will lose 1% of its charge each day.                    Enter the amount ->  
                                                                                                Step 3 - Add the numbers from Step 1 and 2      
                                            = Minimum Daily Current Loss   


Estimated daily current generated by a flat mounted solar panel in winter:

                    Current (Ah)                For Battery Size (Amps)
Wattage    Chicago*    LA                    Chicago*    LA

5W              0.5            1.0                     25            50
10W            1.0            2.0                     50            100
20W            2.0            4.0                    100            200