There are no one-size-fits-all RV solar solutions
The solar system I installed works well because it’s customized to suit our needs and style of camping. If you are planning to add solar power to your RV, I recommend you learn as much as possible up front. When the time comes to take your RV off-the-grid, you’ll be ready to make informed decisions.
Analyzing WHAT others have done, and understanding WHY, is an effective way to learn. So let’s take a look at the off-grid power system on our RV and see if it gives you any ideas.
Off-Grid System Components
The primary components of our off-grid system are typical of what you’ll see in most off-grid systems. The difference between our system and others is the sizes, models, and interconnections between these components:
- 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 – 600 Watts of Semi-Flexible Solar Panels on the roof and 200 Watts of portable solar panels (on the ground connected as needed)
- Solar Charge Controllers – Victron MPPT Solar Charge Controllers
Of course there are many secondary components like cables, connectors, fuses, and switches that tie everything together into a working system. Here’s a detailed 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 12V DC power to our lights, sensors, and other DC powered equipment.
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 6-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 and on the ground collect energy during the day from the sun and send it to the Victron MPPT solar charge controllers which charge the batteries as needed.
What a 24 Hour Cycle of Boondocking Is Like
On a typical evening of boondocking we may use 10-20 percent of battery capacity (30 percent if running a gas furnace). By noon the following day, the battery bank is usually recharged back to 100 percent from solar.
During the rest of the daylight hours we can power the necessary items in the RV (TV, computers, small appliances, gas furnace (if necessary), lights, etc) primarily from solar without drawing much from our battery bank. At sunset our batteries should still be at full charge and ready to power our RV 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.
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.
Installing a power inverter makes it feel like you are hooked up to power. We can run just about everything except our electric heaters, A/C unit and electric hot water heater. Our large battery bank enables us to heat up food in the microwave and make coffee in our Keurig coffee maker. We can even run our gas/electric refrigerator on electric mode for a few hours a day using only power generated by the solar panels. This helps to minimize my propane usage especially while driving.
The game changer was when my wife was able to use her blow dryer. Yes. I was a hero after that.
Here’s a diagram that shows how our inverter ties into our RV’s electrical system.
Important: Disconnect Converter/Charger While Using The Inverter
There was a potential problem I needed to solve — the need to turn off the RV’s converter/charger unit when powered by the inverter. 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. As a workaround, I would manually disconnect the converter when my inverter was running.
Luckily my RV has a circuit breaker which allowed me to manually shut-off power to the converter/charger. All I had to do was remember to do that each time I powered up the inverter.
I later installed an automatic converter shutoff switch which gets triggered when the inverter powers up. Now it’s a no-brainer and is very much appreciated by my wife. All she needs to do is turn on the inverter for AC power. The rest is automatic. No more messing with the breaker on the power panel.
Confused? Here’s a video that explains it all.
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.
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 see the status of our battery bank. Here’s a picture of the battery screen where we can quickly see how much battery capacity we have available and the energy consumption at that time. This is a very cool new addition to my system.
Battery monitors have evolved quite a bit lately. So here’s a list of the top RV Battery Monitors available in 2018-2019 to help you select the right one. Bluetooth, WiFi and remote mobile access are some key features I look for now.
Here is our full solar equipment list
RV Solar Panels
I have two types of flexible solar panels installed on the roof of my RV, Unisolar thin-film solar panels and semi-flexible monocrystalline solar panels. As I’ve expanded my system over the years, I left the Unisolar panels installed. Each panel type has its own array. The Unisolar panel specifications differ from the mono-crystalline semi-flexible panels. So it was necessary for each array to have a dedicated MPPT solar charge controller programmed specifically for that solar panel type.
The Unisolar 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.
The Unisolar panels are still going strong despite the fact that the company went bankrupt many years ago. It’s too bad. They had a great product. I decided not to replace them because, get this, they still out perform the newer monocrystalline semi-flexible solar panels in indirect, low light, and cloudy situations. The only downside is that they take up more space.
The second array includes three semi-flexible solar panels wired in series. I’m now using SUNPOWER semi-flexible panels having tried several other brands with mixed results.
Semi-flexible solar panels are still pretty new to the market, so nobody really knows how long they will last. One of my old HQST panels failed recently after 3 years of use. In July/Aug of 2019 I replaced the 300 watts of HQST panels with 400 watts of SUNPOWER flexible panels.
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 over 600 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 To Mount Flexible Solar Panels On The RV
I’m constantly experimenting with different techniques for mounting flexible solar panels. My latest approach allows for easy removal of the solar panel, provides an air gap for cooling, and does not require any drilling into your RV roof.
You can see my latest mounting system in this video which, after 3000 miles of driving, is working quite well.
Junction Box to Simplify Solar Panel Wiring
I created a junction box on my RV roof to hide and protect all of my 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.
Why Multiple MPPT Solar Charge Controllers?
I have two separate solar arrays up on the roof (one for each type of solar panel). Each solar array is connected to its own dedicated Victron 100/30 MPPT solar charge controller. A third Victron 75/15 MPPT charge controller is for my portable solar panels that I setup on the ground when needed.
All three 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
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.
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I hope this overview provides some insight into what’s possible with an off-grid RV solar system. Here are some other articles that you may be interested in. If you have questions about our setup please leave them below and I’ll do my best to answer. Cheers!