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Solar Controller & Breaker Box

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Solar Power has put Vandwelling within reach of ordinary people. So, with full-time RVing in mind, I have begun with the installation of some solar components.

DISCLAIMER: I’m not an expert at this and this is not a How-To guide. 12V can KILL you; consult an expert first.

The very basic power source in an RV has always been the trusted lead-acid battery. That suddenly allowed you to have some (very) basic amenities, such as lights, but still required regular if not daily visits to a campground or other place where one could recharge it. With the advent of comfort while camping, the appetite for more power grew and Solar became a mainstay in Rving.

Flexible Solar Panels
The solar part of the electrical setup in my Ford Transit consists of three flexible solar panels (LinkSolar GFL-135) with a total of 405 watts. With an average of 200 watts in solar power, most Vandwellers have enough for the basics and some extra luxury; 400 watts allows me to have and use a small fridge, a heater, lights, an induction cooktop and many electronic devices. There are many variables in calculating my power usage, and if it turns out, that more power is needed, I can easily add a couple of ‘mobile’ panels, which I can store under my mattress.

Combiner Box
Dependent on your system, you may decide to use a combiner box, to create a single positive and a negative wire, that go to the solar controller. This can be done on the outside roof or in the interior of the van.
I connect the solar panels with MC4 branch connectors to each other and use a heavier gauge (#8 AWG) MC4 cable to get to the interior.


Breaker Box
Both wires enter the vehicle through a cable gland: a small box that covers the hole where the wires enter and that protects against leakage. From here, the two wires first go to a circuit breaker and then continue to the solar controller. From the controller the wires go to a second circuit breaker in the same breaker box, before continuing to the busbars and batteries. The two circuit breakers (and possibly one more for additional solar panels) protect the wiring and allow me to work safely on the controller and/or panels by disconnecting the power.

Voltage Drop
12V Wiring tends to drop the voltage, even over short distances. Besides keeping the distances between components as short as possible, using the right size (or gauge) wire is of utmost importance. From the first circuit breaker to the controller and the busbars, I increase the wire size from 8AWG to 6AWG. Then to 2AWG from the bus bars to the batteries.

Solar Controller
I use a MPPT controller (EPSolar 3215BN) instead of a PWM controller, as it gives a much ‘cleaner’ signal and doesn’t restrict me on the type of appliance, that I can use. It also uses the extra voltage, to push more amperage into the batteries.

This setup ends at the two busbars. From here, a line goes to the batteries and to a separate fuse box, from which all the individual lights, charge points and appliances are powered.

Next step is the installation of the flexible solar panels on the roof.

* LinkSolar is a sponsor of this website and has graciously made available some tools and equipment, to make this installation a better experience.

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