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Large Mobile Solar Power System

Tuesday, 26 February 2013 00:00 Written by 

After the success of our $150 Small Solar Power Solution, we wanted to take it to the next level. The small solar power solution was intended for emergencies; running small LED lights, power small 12 volt appliances, and for charging batteries and devices. Our main goals were to educate our users by identifying the required solar components, and demonstrate how assemble a budget, yet practical, solar power system. Going into the first project we understood the small solar power system’s limitations, and also understood our user base would like to see a larger system. Our next project, The Large Mobile Solar Power System, will demonstrate how to build a more capable system, which can meet moderate daily power requirements during extended power outages. While, our example system is not capable of running every power-hungry device in your home, it is great for running the “necessary” equipment during a grid down situation. Please download our handout: LMSPS (05-003-13)

The Large Mobile Solar Power System (LMSPS)

When we started designing the LMSPS, we wanted to offer a solution that was portable, modular, and can be scaled to accommodate different user requirements. While we call it a mobile “solar power” system, it must also accommodate wind and hydro. With these objectives identified, we put a lot of thought into our large mobile system. The LMSPS can be assembled and disassembled easily, can be transported in most vehicles, and the individual components can be lifted by the average adult. The LMSPS leverages the lesson learned from the initial project [Small Solar Power Solution], and ensures accessories and wiring methods are compatible with the Small Solar Power Solution.

The LMSPS provides the framework for an extremely modular solar power solution that can be expanded to meet most “survival” power requirements. I love watching YouTube videos of different prepper’s alternative energy systems; 2000 watts of solar, a dozen deep cycle batteries, and multiple charge controllers all neatly organized in their garage. While I am envious of their accomplishments, I still wondered what they would do during a SHTF situation; worst case scenario they had to flee their home. The system would be useless in their garage, while they were in a National Park several hundred miles away. Hopefully, this is all for naught, but the what-ifs always causes concerns.

To identify the system’s components, we had to come up with a practical scenario. It would be great to have a residential solar power system during a Bug Out situation, but that is not practical if you are leaving at a moment’s notice and are restricted by weight (vehicle payload).  So, the LMSPS had to be large enough to accommodate moderate power requirements, but must also fit inside of a vehicle or truck bed, or be mounted inside a recreational vehicle (RV) or trailer. Our minimal component guidelines include: 200 AH of battery storage capacity, 200 watts of solar panels, and a 1500 watt inverter.

There are several good companies out there that offer portable solar power solutions, and on paper and demonstration videos, it appears some of these systems are well made and would meet our minimum component guidelines. However, the prices are extremely high, and there can be a long build period or waiting list. To defend the company’s pricing, the systems may contain proprietary equipment, and the design and manufacturing processes are both expensive (they should be compensated for their investment). Besides pricing, one of our biggest issues with pre-fabricated systems is that are extremely heavy, and would require multiple individuals to move the system. We are not downplaying any company’s products; there are pros and cons to building your own system, and the LMSPS is by no means a budget system.

If you have not already, we recommend purchasing Bug-Out Prototype; please read our review. Surefire Woodsman’s system is hard mounted inside a trailer. While our concepts are the same, a mobile alternative energy system, our system is not hard mounted inside an enclosure. Either situation will work; you need to decide which works best for you.

Before we get into our components, let’s first discuss our key objectives.

Portability – Selecting the Container

To ensure our system was portable, we needed to find the correct container/s for the components. We are using the word container to identify the box/enclosure/rack that our components would be mounted inside. When designing the system, weight was our first major problem. The average weight for a single 100 Amp Hour (AH) Deep Cycle battery is 70 lbs. Two batteries, if wired in parallel would bring the battery capacity to 200 AH (our project goal), and the weight to 140 lbs. 70 lbs is a lot of weight; most males could safely move a 70 lbs container unassisted, but could not safely move or carry a container weighing 140 lbs unassisted.

Sure, you could use a dolly and/or small crane to move your system or set it into the back of your vehicle, but what if you did not have these moving/lifting devices. What if you were the only capable individual of lifting the weight? What if you were alone?  We played the what-if game a lot when designing this system, to ensure it met our portability goals. Our solution: find a container to house a single battery.

Since our batteries were to fit into a single container, we wanted to use the same container for the entire system. We wanted the option of stacking the containers on top of each other. While the system could be disassembled quickly for travel, and moved container by container, we also wanted to have the option to move it using a dolly, if one was available. The container had to be large enough to safely house a battery, but also large enough to hold the inverter and charge controller. The inverter is what caused a challenge here. Most large inverters [1500 watts and greater] are large; the dimensions are dependent on the product. To achieve our stacking objective, the same type of container that housed the battery, would also house an inverter. Additionally, the container/s would have to be rugged enough to withstand the weight; the bottom container would need to support a minimum of 100lbs (4 container stack – 2 battery, 1 inverter, 1 charger controller).

Not knowing where we might use the system, we next focused on environmental considerations. If we were Bugging In, the system would be safe inside of our home. Again, we played the what-if game: what-if we were Bugging Out, camping, tail gating, or transporting the system when it was raining. A tarp or plastic wrap could be used to cover the system, but we wanted the container to be water resistant, without the need to cover it. So our container had to rugged (support the weight) and had to be water resistant.

Our Container Selection: Stanley Bostitch 23” Structural Foam Toolbox. Yes, a normal-large toolbox. The 23” Bostitch toolbox is extremely rugged, is large enough to house a single 100AH battery (we did have to modify slightly), is able to support the weight requirements, and is weather and dust resistant. We were able to pick them up for $20 apiece from our local Lowes. While the toolbox is capable of holding a 70lbs battery, do not lift it using only the handle. If you need a larger toolbox, the Bostitch line includes a 29” model as well. If selecting this container, ensure your batteries will fit inside (send an email to admin@prepperlink for inside dimensions).

Achieving Modularity – The Wiring Dilemma

With our container selected, we focused on the wiring the system. To take advantage of the weather resistant toolbox, our goal was to wire most of the components internally, while having a simple box to box wiring solution externally. Challenges during this phase included the solar panels to charge controller, the battery temperature cable (which runs between the charge controller and the first battery), and the inverter AC outlet. We had to compromise a little container integrity to achieve the tasks.

First, we adopted a 12 volt system architecture, instead of a 24 volt system. This was due to the option of using one battery, instead of wiring two batteries in series. This moderates weight requirements (only one required battery), and to limit complications (if one battery inoperable, you can still use the other). Additionally, the system can be connected directly to your vehicle's battery. 

To connect the containers together, the positive and negative power cables, we wanted to mount to the cables outside of the toolbox. To achieve this, we used battery cable firewall feed-thru panel terminal connectors. These terminal connectors extend the battery terminal to the outside of the box. This allows quick connect and disconnect options.

To wire the solar panels to the charge controller, we contacted AM Solar, and they recommended using their solar power combiner box. AM Solar is one of the leading solar providers to the RV industry, and they are extremely helpful (Prepper Link is no way affiliated with AM Solar). We mounted the combiner box, to the top of the charge controller toolbox.

To wire the battery temperature cable from the charge controller to the first battery, we installed two access ports, and used grommet cable wire hole plastic covers. We also used a grommet to provide the access hole for the AC extension cord. We recommend purchasing the grommets in person, after you have all of your components so that you can accurately measure the hole size needed for running your cables.  

We have included two wiring diagrams; Box to Box and Control Box. 

Key Component List

While your components may differ, our system is comprised of three different tool boxes. 

  • Control Box – The control box is the heart of the system, and houses the charge controller, shunt, power post, and inverter on/off switch. There is also one 12 volt DC outlet.
  • Inverter / DC Box – Houses the inverter, inverter fuse, and DC fuse panel. Additionally, it has three 12 volt DC outlets and an AC extension cord.
  • Battery Box – The battery box can accommodate a large battery; although you will need to ensure your batteries can fit inside your container.


Control Box

Stanley Bostitch 23” Structural Foam Toolbox (The link is to Amazon, but compare the price at your local hardware store)

Junction Box, 6” x 6” x 4” – Used to mount the Charge Controller, secured by Velcro to toolbox.

Junction Box, 8” x 8” x 4” – Used to mount the remote, shunt, On/Off Disconnect Switch, and Power Post. Secured by Velcro.

2 x Black Terminal Connector – Used to connect wire boxes together (1 connects to Battery Box/es, 1 connects to Inverter/DC Box). If you are not monitoring your power consumption using a shunt, you can get by with only one terminal connector.

2 x Red Terminal Connector – Used to connect wire boxes together (1 connects to Battery Box/es, 1 connects to Inverter/DC Box). Our inverter draws power even when powered off. To counter this, we ran a switch to control on/off positions. However, you do not want your batteries run on the same line. Both are mandatory if your inverter consumes power even with off.

Charge Controller – The charge controller is the heart of the system. It regulates charge to the battery.

Charge Controller Remote and Shunt – The remote allows you to see your power input/output as well as advanced configurations for your Blue Sky charge controller. The shunt is connected to the negative power cable, and measures power consumption.

Power Post – This is the center of your wiring system.

On/Off Disconnect Switch, must be connected to a positive cable. We use it to between the power post to the Inverter/DC box.

AM Solar Combiner Box – can accommodate other alternative energy inputs (wind, hydro)

Non-Fused Disconnect – Used to cut power from the solar, wind, hydro inputs to conduct maintenance on the system.

12 Volt Outlet – We wanted to have a DC power source, even if the Inverter/DC box was not connected. Purchase from eBay.


Inverter / DC Box

Stanley Bostitch 23” Structural Foam Toolbox (The link is to Amazon, but compare the price at your local hardware store)

1 x Black Terminal Connector – Connects directly to the control box, on the secondary negative terminal, which is connected to the shunt.

1 x Red Terminal Connector – Connects directly to the control box, on the secondary positive terminal, which is connected to the On/Off Disconnect Switch.

Go Power 1500 Watt Pure Sine Wave Inverter – We also recommend purchasing the on/off remote switch.

Go Power Amp Fuse – Standard application with inverters.

Go Power Inverter Remote ­– Allows the inverter to be turned on/off remotely. Mounted to the outside of the box.

DC Blade Fuse Box – Connects to the 12 volt outlets. Provides 12 independent connections.


Battery Box (List is for each individual box)

Stanley Bostitch 23” Structural Foam Toolbox (The link is to Amazon, but compare the price at your local hardware store)

1 x Black Terminal Connector – Connects directly to the control box, on the primary negative terminal, which is connected to the Power Post

1 x Red Terminal Connector – Connects directly to the control box, on the primary positive terminal, which is connected to the Power Post.

100 AH Battery – This battery will fit inside the toolbox, however slight modification to the toolbox top support will be needed (Dremel tool recommended).



2 x Kyocera 135 Watt Solar Panels – Total of 270 Watts. We installed two heavy duty hinges and a handle for easier movement. Eventually, we will adopt the system identified in the Bug-Out Prototype video.


  • A Dremel tool, or equivalent, is highly recommended. For this system, a few of the components will need to be cut/trimmed. The following only applies to the above listed items; your components, if different, may not be compatible.
  • Inverter – Part of the support frame will need to be cut to ensure it seats correctly inside the toolbox. This is a heavy gauge metal; I used a Dremel Tool with metal cutting disk.
  • Battery Box – Two supports will need to be removed on each battery box lid. The supports come into contact with the battery terminals, and will not allow the box to be shut. Simple fix, and it does not compromise the integrity of the tool box.
  • Battery Box – I used expanding foam to make a tight fit inside of the toolbox. You can pick this up at any hardware store. 

Wiring Sizes

  • We used 4 Gauge wire to connect the terminals together (box to box connections), the Power Posts to secondary terminal connectors, and the Power Posts to the Shunt.
  • On the charge controller, we used eight gauge wire (which was recommended by AM Solar) to connect the Disconnect Box to the Charge Controller, and the Charge Controller to the Power Posts.
  • All 12 Volt outlets were wired with 16 Gauge wire.
  • To connect to the solar panel/s, we used a 10 Gauge 2 Pole Connector.
  • Don’t forget to purchase terminal connectors for your wire sizes (we used 4, 8, and 16 gauges).   You can also purchase pre-fabricated battery cables.


This instructional was intended as an overview, so if you have any questions, please let us know. Our Large Mobile Solar Power System is extremely modular, and can be used for various tasks. Being modular, you can start off with the control box, and add the additional boxes over time. Or, you can connect to an existing battery bank to charge batteries (maybe your car battery). Our example system utilizes two batteries; however you can add more.

We have included a wiring diagram that identifies how the major components are connected. Keep in mind that our wiring technique may differ from others, but it works and maximizes the capabilities of our Charge Controller Remote and matches our modular box approach. If you are not using a remote, or have a different version, or will hard mount your system inside a vehicle, trailer, or RV, your wiring method may differ. Lastly, we also recommend purchasing the Bug-Out Prototype DVD from Surefire Woodsman, so that you can see a mounted mobile solution.

Again, please let us know if you have any questions.  Don't forget to download our handout: LMSPS (05-003-13).

Last modified on Tuesday, 12 March 2013 18:11
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