"Freedom" the RV Goes Solar - Phase I

Shortly after purchasing "Freedom", we decided we wanted the ability to do some boondocking on occasion. After doing a little research, we realized we would like (or should I say need) to add solar to her in order to be able to spend some time "off the grid".

If you've looked into adding solar to your RV, you probably already know that it can be expensive! After some quick calculations, we determined that it could cost anywhere from $5,000 to $15,000, depending on how far we wanted to go with it. We developed a plan and settled in on something in the $8,000 range, but that would still be too much for us to afford all at once. To make it more affordable for us, we decided to break the project down into a few phases. This would allow us to implement the different pieces at different times based on when it was affordable.

We were already having issues with the onboard converter/charger, so we decided to start with the purchase and installation of the inverter/charger and the necessary equipment to connect it and get it functional.

Because we are DIY kind of people, we will be performing all of the labor ourselves. Mark has a BS in Electrical Engineering but is new to solar systems, so some research will be necessary.

The Plan

After doing a lot of online research, Mark drafted up a schematic for what we wanted to install. This schematic doesn't show all of the details, but does show the major components of the system.

We decided to break the project down into the following phases.

Phase I: Inverter/Charger and Battery Monitoring
Phase II: Solar Panels and Charge Controllers
Phase III: Lithium LiFePO4 Batteries
Phase IV: System Monitoring
Phase V: Alternator Charging

Watch for future posts about Phases 2 thru 5.

Phase I: Equipment Needed

We wanted to go with something capable of servicing both sides of our existing 50 amp service so that we would have the ability to use any of the onboard appliances, no matter which 120 volt leg they were connected to. The Victron MultiPlus-II 2x 120V was the best fit for this application.

We also wanted to add battery monitoring during this phase, but decided not to implement full system monitoring until a later phase. So, we decided on the Victron BMV-712 for this phase.

It was also necessary to purchase the Victron MK3-USB Interface in order to change settings on the MultiPlus-II.

List of the major equipment necessary for Phase I:

Phase I: Equipment Installation

In order to install the equipment, we needed to find a location in the RV that would accommodate all of the electronics needed. With inside storage space in an RV always being in short supply, we decided not to use any of the inside cabinets or closets, as those would be needed for other things during our travels. Also, since we had already packed our outdoor necessities and filled most of the basement storage, we didn't want to designate any of that storage space for solar equipment. However, we realized that there is quite a bit of "wasted space" in our RV that is not normally accessible for use. We located a hidden space under the nightstand next to the bed and decided that would be the best location to install most of the equipment. This space was also located directly above the house battery compartment, so it would make it easy to run cables from the batteries to the equipment.

The first step was to make some modifications to the existing house battery compartment to accommodate the future Lithium LiFePO4 batteries, install bus bars in order to connect all the batteries together, and install the 400 Amp fuse and battery disconnect. The original battery compartment configuration had space for four of the typical 12 volt lead acid batteries (about 7" x 12" for each battery), but we wanted to make room for up to four of the larger lithium batteries (about 11" x 21" each). We could fit two lithium batteries of this size in the existing house battery space, so we needed space for two more. Since this battery compartment was as tall as the other basement storage compartments, we decided to add a shelf above the bottom batteries to hold the additional two batteries. The custom made bus bars, 400 amp fuse and battery disconnects were installed on each side wall of the compartment next to the added shelf. We also added new 4/0 AWG cables from the batteries to the bus bars.

The next step was to make a few modifications to the hidden space under the night stand next to the bed. In order to make room for the equipment, it was necessary to move an existing heater vent and duct to a new location. The vent was relocated to the side of the bed and the duct was extended to reach the new location.

We added a shelf in the hidden space to give us more surface area to mount the equipment. The inverter/charge was mounted on the shelf and the Lynx Distributor was mounted on the side wall of the compartment. The shelf was placed on a slight incline to help with airflow through the inverter/charger. New 4/0 AWG cables were added to connect the battery bus bars to the Lynx Distributor as well as to connect the inverter/charger to the Lynx Distributor. The shunt was installed on the side wall under the Lynx Distributor and new 4/0 AWG cables connect it to the Lynx Distributor as well as the negative battery bus bar in the house battery compartment. A new 4/0 AWG cable also connects the frame ground to the Lynx Distributor.

The panel that covers the hidden space was modified to make it easier to remove for accessing the compartment. We added a piece of 1/4" plywood to the back of the existing thin panel in order to make it more sturdy so it would not need to be nailed into place. We then added Velcro to the backside of the panel and stuck it into place, thus allowing us to easily remove it when necessary.

The BMV-712 was mounted in the panel so that we could monitor battery voltage. We also added a cabinet fan in the location where the heater vent was previously located. This allowed us to cover the hole that was left from relocating the vent, as well as add some circulation to help ensure the equipment inside the compartment does not overheat. We also installed a temperature controller to activate the fan when needed, so that it doesn't need to run all of the time.

Notes on Existing Inverter

We decided to leave the existing inverter in place and connected, but installed a secondary battery disconnect so that we could turn off DC power to it. This would allow us to use it during an emergency if necessary (i.e. Victron Inverter/Charger has issues), but typically, the switch will be off and it will be disconnected.

Stay tuned for future "going solar" posts!!!

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