In this final section of our 5-part series on solar, we will finish the installation of the system by installing the inside components.
In the first 4 sections we covered: What Is Solar And Do I Need It, What Parts Are Needed, How Much Solar Do I Need, and the Installation Of The Rooftop Components. If you have not read those articles, for clarity proposes, please refer back to those articles first.
Solar charge controller
The Victron 100/30 MPPT is the brain of the entire system. Its main function is to extract the maximum available power from the solar array by making them operate at the most efficient voltage (maximum power point). In other words, the charge controller checks the output voltage of the solar array and compares it to the battery voltage. It then adjusts it to get the maximum current or amps into battery.
The Victron 100/30 controller is Bluetooth capable. Meaning you can set, monitor, and control its functions from a smartphone. This also means that you do not need constant access to the controller. I chose to install mine under the front dinette seat hidden from view. The only thing required is a little free air space around it to prevent overheating.
Under normal operation, the Victron 100/30 charger is capable of providing up to 30 amps of charging current to the batteries. Therefore, you should “fuse” the circuit to prevent damage.
I placed a 40-amp DC breaker on the positive lead inline between the charger and the batteries to prevent overflow of current and protect the batteries. I chose a breaker with a 10-amp higher current tolerance than the controller, which will allow the Victron charger to operate at full capacity but trip if there is a problem.
I prefer the use of a D/C breaker in this case because they can simply be reset, but you could use a properly-sized fuse and fuse holder.
Now that we have a properly fused charger installed, we have to do something with all that power.
I installed four LifeLine AGM 6-volt batteries. This gives me a 440ah battery bank. Due to the weight and size of this battery bank, I was forced to relocate my batteries from the Airstream factory battery box mounted on the tongue of the trailer and install them inside the trailer.
I installed two batteries on the street side under the lounge and two on the curbside under the kitchen counter. Both install locations are located right in front of the axles. These two install locations were “dead space” within the trailer. Meaning we did not sacrifice any storage and it will provide the best balance and weight carrying capability.
Safety note: Do not install flooded lead-acid batteries inside your RV because they release hydrogen gas and oxygen which must be vented due to the risk of fire. Only sealed batteries such as AGM and Lithium batteries can be installed inside.
Each of the LifeLine batteries rests inside a NOCO battery tray that is secured to the Airstream’s floor to prevent them from moving during travel. The 6-volt battery pairs are wired in series. This creates two 12-volt banks rated at 220ah each. Each 12-volt bank was then wired together in parallel providing the 440ah total bank.
I used an online wire calculator and decided to use 2AWG wire for all my battery connections. I purchased a hydraulic crimping tool to make my own custom length battery cables. I believe having the ability to make your cables custom lengths allows for a cleaner and neater install, so purchasing a crimp tool is a good investment.
Battery monitor and shunt
Installation of a battery monitor is not required but is a great addition. It will allow you to monitor your battery bank’s state of charge to better keep up with how many Ah you have available to use. This will prevent you from damaging your batteries by over-discharging them.
Think of the battery monitor like a fuel gauge. We chose to install a Victron BMV battery monitor. The battery monitor measures power going in and out of the battery through something called a shunt.
The shunt must be installed with the negative battery lead running through it. In other words, the negative lead that comes from the battery bank MUST go to the shunt FIRST and then it can continue to the negative bus bar or frame ground distribution.
By running ALL the negative draws through the shunt you can ensure that the battery monitor is measuring all DC draws and providing you with accurate information. Once the shunt is installed inline with the batteries’ negative lead, the monitor is connected to the shunt via a Cat-5 data cable.
The monitor head unit will need to be installed in a location that is easily viewed for ease of use. I installed our Victron BMV in the wall beside the refrigerator because of its ease of viewing and ease of running the Cat-5 Data cable to that area.
Battery disconnect switch
I also installed a Blue Sea 3002 HD 4-position switch on the positive battery leads. This switch will allow me to disconnect the batteries from the system, run off bank #1, run off bank #2, or run off both banks at the same time. Options are always nice!
From the Blue Sea Disconnect Switch, the batteries’ positive lead is wired to the RV’s 12 distribution panel. This fuses and sends 12-volt power throughout the RV, powering lights, water pump, and various other DC powered equipment.
With the batteries in place and all the wires connected, our install is now complete! We have the solar panels mounted on the roof and connected through a rooftop mounted combiner box. We have 4 AWG wire ran from the combiner box to the Victron 100/30 solar controller with a panel disconnect switch installed inline.
The Victron 100/30 charger is connected to the batteries with a 40-amp DC breaker installed inline. Finally, the four Lifeline batteries are connected to the RV’s 12-volt distribution panel with negative battery leads running through the Victron BMV battery monitor’s shunt and the positive lead running through the Blue Sea battery disconnect switch.
You are now ready to enjoy the fruits of your labor and the satisfaction of a job well done. Now get out there and enjoy the great outdoors!
Feel free to reach out if you have questions and don’t forget to follow us @Airstream_Nuts_and_Bolts on Instagram for our most current travel and project information.
See our previous articles for reference: