How to Wire a Danfoss BD35

Disconnect your solar panel's electrical terminals from the panel itself so that you don't have any power running to the terminals. Never work on a live electrical circuit.

Set the Danfoss BD35 compressor at the location where it will be permanently installed to provide cooling. Measure the distance of the run from the compressor to the solar panel electrical connections. The length of the wire and the voltage supplied will determine the gauge of the wire you should use. For 10- to 12-volt power, runs shorter than 13 feet can use 12 gauge wire; use 10 gauge wire for runs between 14 and 20 feet; and use 8 gauge wire for runs up to 33 feet. If you are running voltage higher than 12 volts, you can use 12 gauge wire up to 26 feet; 10 gauge wire up to 39 feet; and 8 gauge wire to 66 feet. Do not exceed the maximum length of the wiring -- 33 feet for 12 volts and 66 feet for 24 volts and higher.

Cut two wires, one red and one black, to the length required to run from your solar panel electrical poles to the BD35 model compressor. Depending on the connection type for your solar panel, you may need different connectors and tools to make the connection with your solar panel. Connect the black wire to the solar panel negative terminal.

Connect the fuse circuit to the positive terminal on the solar panel. Do not insert the fuse yet. Connect the red wire you cut to the other end of the fuse circuit. If you're running at a lower voltage you need a higher amperage fuse. The 12-volt systems need the 15 A fuse; 24-volt and higher systems take the 7.5 A fuse.

Strip the unconnected ends of the red and black wires to expose a quarter inch of conductive material. Slide a female spade connector on each wire and then crimp it in place with the crimping tool. Wrap the wire and crimped connection with electrical tape.

Plug the electronic unit into the compressor using the wiring harness attached to the unit. Slide the unit into the mounting bracket on the side of the compressor so that the terminal labels face you and are right-side up. Snap the hole, which is to the right of the terminal labels, over the screw on the compressor mounting bracket to secure the unit in place.

Connect the black wire to the negative terminal at the top of the electronic unit and the red wire to the positive terminal just below that.

Connect optional components. A thermostat connects to the C and T terminals. A fan can connect to the + and F terminals. The fan must be rated for the voltage produced by your solar panel system. If you also want an LED light to show the operation of the compressor, connect a 10 mA LED to the + and D terminals. You will need to join the fan and LED connections to the + terminal for this setup.

Insert the fuse in the fuse circuit and reconnect the solar panel to the electrical panel. You will need to connect the compressor to the cooling system, as per the manufacturer's instructions, to complete the installation.