Electricity, Solar, Sustainability

12 Volt Electrical

We will have 2 separate 12v systems on-board; the engine circuit, and the living circuit. The 2 systems will be separate, with the ability to recharge the engine battery from the living, if needed. This is beneficial to our readers since this will be an independent system and could be used anywhere, not just in a Skoolie, just install as your application requires.

Solar Panels to the Solar Charge Controller

If you’re unsure about Solar Panels, check out our brief explanation, here. 12v DC electrical systems are NOT complex; at the most basic level, you have two sides, a positive (red) and a negative (black), just like a car battery.

We’ll start our planning at the rooftop solar panel combiner box, where all of the solar panels positive and negative lines combine, to power the solar charge controller.

Solar Panel Combiner Box
Solar Panel Combiner Box

You can see in the example on the right, all of the smaller #8 gauge negative leads (from individual solar panels) are connected to a larger all black #4 gauge wire.

On the positive side, you can see each panel has a circuit breaker before connecting to the larger #4 gauge positive wire. The circuit breakers are important! If an individual solar panel malfunctions, it will trip the circuit breaker instead of potentially taking out the whole system or starting a fire! It’s better to plan for the worst and end up with reduced power, over no power.

We will have 1600+ watts of solar panels and as such, we will need the larger #4 gauge wires to transmit electricity as efficiently as possible.The length of wire needed to join the combiner box to your solar charge controller will also effect the gauge of wire needed, therefore it is important to keep components as close as safely, and reasonably possible. You will need to determine which gauge of wire you need based upon the amount of Amps (Amperage) you are planning to transmit. I will find a link asap to explain voltage and amperage by distance in wires.

Solar Charge Controller to Battery Bank

We will probably use #2 gauge welding wire from the MPPT charger to the battery bank bus bars, and from the bus bars to the individual batteries. Some may think this is overkill, but a well designed system is less likely to fail, and provides easy maintenance when required.

Bus Bars.jpg

The battery bank will be connected together using Bus Bars. Bus Bars are simple, take 2, and place them on either side of the battery bank, 1 side is for all of the positive connections, and the other side is for all of the negative connections. This removes the need to have wires crisscross over each other. This is known as a parallel circuit, the voltage stays the same, but the capacity of the battery bank increases with each additional battery.

Connecting  your appliance to the bus bar, instead of an individual battery, will give you the full capacity of the battery bank, as well as balance the load on each cell. As such, the bus bars will also be used to supply power to the 12v fuse panel and our 120v Inverter.

Solar Power to Run Your Skoolie

Don’t wrack your brain for too long trying to figure out how we charge the batteries while using them. If the power coming in from the Solar Panels, is greater than the power required, the excess is used to charge the batteries.

  • If (Power In > Power Out) Than (Batteries Charge)
  • If (Power In < Power Out) Than (Batteries Drain)

From the Bus Bars, a positive and a negative wire will be connected to a 12v Fuse Box. 12v appliances such as water pumps, LED lighting, etc. will be powered through the 12v fuse box. All grouped components should have individual fuses; water pumps, fans, LEDs, etc. Fortunately this inexpensive 12V Fuse Panel provides space for 12 fuses, as well as common positive and negative poles to connect to the Bus Bar.

With 12 Spaces, we will have enough for necessities, with spares for expansion…

  • #1 Indoor LED Lighting (10 Amp Fuse)
  • #2 Outdoor LED Lighting (15 Amp Fuse)
  • #3 Fresh & Grey Water Pump (20 Amp Fuse)
  • #4 12v to 5v Converters, 3A each (15 Amp Fuse)

For our cell phones and tablets, I’ll install several female USB ports around the bus; powered by these 12v to 5v 3A Converters. For the laptop and tv, along with any other needs, we will be using a 2000w inverter hardwired to GFCI outlets strategically placed throughout our skoolie. The 2000w inverter will be connected directly to the battery bank bus bar due to the high power draw.

Be sure to check out how we achieve “Home Like” On-board 120V Electricity on our skoolie.

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