Analyzing WHAT others have done (plus some trial-and-error) has been an effective way for me to learn about solar. So let me give you a close-up look at the DIY off-grid power system in our Class C motorhome. Hopefully you’ll get some good ideas from it.
The solar system I installed works well because it’s customized to suit our needs and style of camping. There are no one-size-fits-all RV solar solutions. Your needs will be different than ours.
I recommend you learn as much as possible up front if you’re are planning to add solar to your RV. When the time comes to pull the trigger on a system of your own, then you’ll be ready to make informed decisions about what components are right for you.
Do You Have Questions About RV Solar?
Check out my FREE Guide to RV Solar Panels that answers many common questions. You can download the FREE solar guide here.
- Off-Grid System Components
- RV Solar Panels
Off-Grid System Components
The primary components of our off-grid system are typical of most off-grid systems.
- Battery Bank – 400 Amp Hour Lithium (LiFePO4) Deep Cycle Batteries (4 – 12 Volt Batteries)
- Power Inverter – 2000 Watt Samlex Pure Sine Inverter
- Battery Monitor – Simarine PICO Battery Monitoring System
- Solar Panels – 1000 Watts of Semi-Flexible Solar Panels on the roof and 230 Watts of portable solar panels (ground deployed as needed)
- Solar Charge Controllers – Victron MPPT Solar Charge Controllers
Our system differs from a basic system only by the quantities, sizes, models and interconnections between components. Not listed are the many secondary components like cables, connectors, fuses, and switches that tie everything together into a working system.
Here’s a diagram of our system that illustrates how the solar and battery charging components are connected.
How the Solar and Battery Charging Part Of The System Works
The large deep cycle battery bank is at the heart of the system and provides 12 volt DC power to our lights, sensors, and other DC powered equipment. It also powers our power inverter which provides household AC power throughout the RV.
You can see how I mounted and wired our four 12 volt lithium (LiFePO4) Battle Born batteries in parallel to achieve 400 amp hours of capacity in this video.
Before upgrading to Lithium batteries, I had four six volt AGM batteries wired in series/parallel to achieve 450 Amp Hours of capacity. This article will walk you through how to make those connections.
Our Simarine PICO Battery Monitoring System (BMS) measures the energy flowing in and out of our battery bank and informs us how much is available at any given time.
Solar panels on the roof collect energy during the day from the sun. That energy is sent to multiple Victron MPPT solar charge controllers which regulate it to safely and efficiently charge the batteries.
What a 24 Hour Cycle of Boondocking Is Like
On a typical evening of boondocking we may use 10-30 percent of battery capacity powering our electronics, watching movies and using our electric kitchen appliances. By noon the following day, the battery bank is usually recharged back to 100 percent from solar.
We hate wasting free solar energy once the batteries are fully charged. So while the sun is still shining we try to make use of the available solar power before nightfall. At sunset our fully charged batteries provide the power we need throughout the evening and night.
Each day the cycle repeats. On rainy days, our battery bank will take a deeper discharge but still absorb some solar energy. Lithium batteries now give us more reserve power. This allows us to discharge them all the way down to 10-20 percent of their capacity if necessary.
We’ve sized our lithium battery bank to provide us with several days of power (practicing power conservation) if solar power is limited.
Using an Inverter for Household AC Power
The role of our Samlex 2000 watt pure-sine inverter is to convert 12 volt DC power to 120 volt AC power. The AC power from the inverter simulates a shore power connection and powers all of the AC circuits and household receptacles in the RV.
The game changer was when my wife was able to use her blow dryer. Yes. I was a hero after that.
Installing a power inverter makes it feel like you are hooked up to power. Our large battery bank enables us power just about everything we would on a shore power hookup. We regularly use our microwave, induction burner and Keurig coffee maker. Running our air conditioner and hot water heater for limited periods of time is even possible after adding lithium batteries.
Throughout the day I switch our refrigerator over from gas to electric. It runs off of the inverter and batteries until night time when I’ll switch it back over to LP.
Here’s a diagram that shows how our inverter ties into our RV’s electrical system.
Important: Disconnect the Converter/Charger While Using The Inverter
The converter/charger needed to be disabled while running on inverter power. Here’s why.
Without disconnecting the converter/charger (which converts AC back to DC and charges the batteries from shore power) the batteries would be charging themselves through the inverter and converter/charger. This is not a safe scenario.
To solve this problem, the power to the converter/charger is wired to the shore power side of the automatic transfer switch (ATS). This setup only allows battery charging to occur when connected to shore power (not inverter power).
There are a few solutions to this problem which I cover in detail here in this article: How To Safely Install a Power Inverter.
Keep in mind that this is not an issue in larger RVs that have the inverter, charger, and transfer switch combined into one unit. These are typically called hybrid inverters.
How We Charge Batteries From the Alternator While Driving
The engine in our motor home also charges our deep cycle batteries when necessary. I installed a Renogy DC-to-DC charger between the alternator and battery bank to protect my alternator from excessive current draw and to ensure the batteries are charged properly.
In this video, I’ll walk you through how the alternator charging system works with my Battleborn lithium batteries.
Note: Alternator charging is my secondary means for recharging my battery bank since removing my onboard generator. Check out this video to see how and why I removed my generator.
Why a Battery Monitoring System Is Important
The primary reason for having solar in the first place is to charge our deep cycle batteries.
Without a battery monitoring system, I would have no idea how much power I am using in the RV or how much battery capacity is available. Every off-grid system should include a battery monitoring system (with or without solar). It should be the first thing you install.
I have the SIMARINE PICO Battery Monitor System in our RV which makes it very easy to monitor power consumption and state of charge of our battery bank. It clearly shows how much energy is going in and coming out of the batteries in real time. This is a very cool new addition to my system.
Here’s a picture of the PICO touch screen.
Battery monitors have evolved quite a bit lately. So here’s a list of the top RV Battery Monitors available in 2021 to help you select the right one. Bluetooth, WiFi and remote mobile access are some key features I look for now.
List Of Preferred RV Solar Equipment
RV Solar Panels
As I’ve expanded my system over the years, I left the Unisolar panels installed. There are three arrays that cover each section of my RV roof. Multiple arrays in parallel helps maximize efficiency.
SUNPOWER flexible solar panels are mounted on the front and rear of the roof. Each pair of 170 watt panels are wired in series and have their own dedicated Victron solar charge controller. Victron’s built-in charge controller synchronization capability has made my parallel controller setup very effective and efficient.
The Unisolar thin-film flexible solar panels were installed in 2012. At that time they were the only flexible solar panels available. There are two 64 watt panels and one 128 watt panel. The two smaller panels are connected in series and those are connected in parallel with the 128 watt panel.
Unisolar went bankrupt many years ago. It’s too bad. They had a great product. Nevertheless, the Unisolar panels I installed have continued to hold up and perform well after all these years. The only downside is that they take up more space.
You can see the difference in this photo (below). One of the rectangular monocrystalline SUNPOWER flexible panels can crank out the equivalent of roughly 70 percent of all three skinny UNISOLAR panels combined.
Unlike the monocrystalline solar panels though, I can safely walk on the UNISOLAR panels. That’s a big plus given the limited room to move around up there.
Many ask “Why are you still using semi-flexible solar panels?” I’m still a fan of flexible solar panels due to their light-weight and low-profile features. Plus they generate more power on average than comparable traditional glass panels. Looking at my RV, you wouldn’t know I had 1000 watts of solar up on the roof and I like that.
I’ll continue experimenting with flexible solar panels report back to you as they improve over time.
How We Mounted Flexible Solar Panels On The RV
I’m constantly experimenting with different techniques for mounting flexible solar panels. My latest approach does not require any drilling into your roof and includes a track system for easy mounting and removal of the solar panel.
You can see my latest mounting system in this video which, after several thousand miles of driving, is working quite well.
Junction / Combiner Box to Simplify Solar Panel Wiring
A junction box on the RV roof hides and protects all of the solar panel connections. All of the solar panels are wired directly to this junction box.
Unlike a typical solar combiner box used to connect solar panels in parallel, these terminal blocks also allow me to connect panels in series and split my panels into two separate solar arrays. I can also change my configuration in the future without having to move or run new cables.
I eliminated all of the cable “T” connectors and MC3 to MC4 adapters after installing the junction box (see video below). All all connections are now made inside the box.
Here’s a video to show how I built and wired the Solar Junction Box.
Multiple MPPT Solar Charge Controllers – Why?
There are multiple solar arrays on the roof. Each solar array is connected to its own dedicated Victron MPPT solar charge controller. A separate Victron 100/20 MPPT charge controller is for my portable solar panels that I setup on the ground when needed.
All solar charge controllers are wired in parallel and share the same charge profile for charging my lithium battery bank.
Here’s a video explaining how and why I installed my MPPT solar charge controllers in parallel to charge my battery bank.
How Everything Works Together – Full System Walkthrough
As you can see, there are many system components working together to provide power to our RV off-the-grid. Understanding HOW and WHY I configured our system this way will hopefully provide clarity as you analyze our setup.
Take a few minutes now and watch this video walkthrough of our entire system in operation. Keep in mind that I’ve upgraded to lithium batteries, added more solar and a DC-to-DC battery charger since making this video.