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Free 300-Watt Solar System Plans (RVs and Campers)

Click here to download the 300 Watt Solar System Diagram

This system will produce around 130 amps per day maximum. That’s enough energy to run a Maxxairfan, a small DC Refridgerator, LED lights, Cellphones, Laptops, and a water pump for the kitchen. During very sunny weather you can even do most of your cooking with solar energy.

You can expect to pay anywhere from $500 to $1000 for this size solar system without the cost of batteries and tools. Your exact cost will depend on where you source your equipment.

Project Components

Solar Array


Everything Else

Installation Overview

Most mobile solar systems can be divided into three basic parts.

  • Part A: The Battery Bank, for energy storage.
  • Part B: The main component panel consists of the charge controller, fuse distribution, and a power inverter.
  • Part C: The rooftop solar array.

We’ll build each of these parts separately and connect them together at the end of the project.

Skills required to build a solar system

You should be comfortable with basic hand tools and crimping wires. But you don’t have to be an expert or have previous experience with electricity.

Read this entire article first before beginning the project. If you feel uncomfortable performing any of these steps, just stop, contact a professional or feel free to send us a detailed email and we will personally assist you to the best of our abilities.

Building the Battery Bank

Where to mount your batteries

They need to be installed somewhere secure, where they won’t freeze or overheat. A cabinet or box that allows good airflow, and prevents anything from damaging them is your best bet.

Your inverter should be mounted close to the batteries. If you’re using lead-acid batteries, do not mount the inverter above the batteries. Lead-acid batteries can produce flammable gas when they are overcharged. This gas can be ignited by the inverter.

Sizing your Battery Bank

Your Battery Bank size is dependent on the size of your Inverter if you choose to have an inverter. Because power Inverters draw so much energy at one time, they require a large power source. The larger your inverter, the larger your battery bank needs to be.

We’ve made a handy chart with inverter and cable sizes. But always read the Inverter manufacturers guidelines on wire, fuse, and battery sizes.

We always recommend LiFePo4 Batteries for mobile solar systems. They’re effectively 1/3 the weight and twice the capacity of traditional batteries. Not to mention they have a much longer lifespan and can easily be resold once you no longer need them.

How to wire your Batteries

For this build, you’ll wire your batteries in parallel, which means you’ll connect each positive terminal together, and each negative terminal together. This will keep their voltage at 12Volts. In this configuration, you can wire as many batteries together as you like, unless otherwise specified by the battery manufacturer.

Battery Diagram

Component Panel Assembly

In this step, you’ll build what is essentially the electrical panel. It will contain as many individual electrical components as you can reasonably install on it.

Building this section separately allows you to install components comfortably in your house, and then take the entire thing to your van or RV for installation. Should you ever need to service an item, you can remove the entire panel and perform the work easily.

Komponentenboard Beispiel Solarsystem

Lay your main components out on the board first without attaching them to the board.

Attach the larger wires to the individual components. This way you’ll be able to see if the wires are able to bend at the proper angles. Once you’re satisfied with the basic layout, secure everything to the board.

Install the board in a well-ventilated spot in your van.

Installing Rooftop Solar Array

The final step is to install the solar array.  You might have noticed that we’re using multiple smaller solar panels instead of one larger panel, there’s a good reason for that.

If we wire multiple solar panels together in series we will raise their Voltage. Higher Voltage Systems are more efficient and produce energy for longer amounts of time. We’ve written an article that explains this in more detail.

We recommend bolting your panels to a roof rack or using a solar panel installation kit. This is the most secure method. You won’t be worrying about them flying off and hurting someone.

We do not recommend gluing panels to the roof of a vehicle. We know many people have done this successfully, but you’ll have to search elsewhere for installation advice.

Connecting Everything Together

Once all three stages of your build are complete, you can begin to connect them together in this order.

Step 1

Make sure the main battery switch is in the open (disconnected) position before proceeding. Take the two main cables from your battery bank and connect them to the busbars of your component panel. Once they are connected securely, you can turn the Battery Switch to the closed (connected) position, this will connect the batteries to the circuit.

Step 2

Make sure that your solar panel switch is in the open (disconnected) before moving forward.
Connect the main solar array wires to the solar main switch. Before you turn the solar switch, make sure your batteries are connected, and the battery switch is closed (connected). You should never connect solar panels to a system without batteries, otherwise collected energy has nowhere to be stored.

Step 3

Turn the solar switch to the closed(on) position. If everything is connected properly and the sun is shining, you should be collecting solar energy.

At this step, you’ll want to test your system thoroughly. Run your inverter with different devices while monitoring the components. While you test components be sure to check that wires are not becoming excessively hot.

Looking for an easier option?

A Solar Generator might be exactly what you need. These All-In-One devices require no tools or assembly. Here are a few options that cover small, medium, and large energy requirements.

Jackery Explorer 160 Small budget-friendly Power devices like phones and laptops. Learn more…
Anker 535 Medium-sized option. Power devices, fans, electric coolers, drones, and more. Learn more…
Anker 757 Large-sized option Power almost anything you would at home. Learn more…

Browse our other 12-Volt Systems

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