Small Solar System Provides BIG Power!

Don’t have much space on your RV roof for solar, but have big power needs? It’s not about how many solar panels you can fit up top, it’s about building in flexibility to charge up your off-grid batteries in multiple ways.  We’ve lived with nearly 100% off-grid power as we’ve traveled full-time for over 13 years in our vintage camper – from California to Newfoundland and Alaska to Florida!  It’s a wonderful life where we can live, work, and play, from anywhere we want to be.  We’ve traveled throughout all 49 US states connected by road and, as of this summer, we finally made it to our final Canadian province (Newfoundland & Labrador) to which you can tow your home on wheels.  Sixty-one states, provinces, and territories in total, all in a 1957 solar powered travel trailer.  Follow us on social media to join in the fun…we aren’t stopping anytime yet!

Here are the 3 ways we keep our off-grid batteries charged up:

1. Solar Power (while camping / driving)

2. Engine Power (while driving)

3. Grid Power (very occasionally)
   
   

1. Solar Power: Where it All Begins!
We have 2 x 100W Renogy flexible solar panels on the roof of the camper.  They are lightweight, low profile, and perfect for our RV situation.  In addition, we have a Renogy 400W lightweight portable panel which is a workhorse and folds up quickly to store away when not in use.  We have a selector switch which controls which solar panel array is charging our inside battery system, because a 200W array won’t play well with a 400W into the same charge controller.  But we have a big flexible workaround to deal with this problem that we’ll discuss a bit later.

The 400W lightweight portable panel is a lifesaver during various times of year when 1) we want to park our camper in the shade and still pull in solar power out on a 30 foot extension cord, or 2) when the solar angle is low during the late fall through early spring and we need more solar collection surface area.  

Watch our RV Solar Tour in action to see how we make it all work with a modest system for under $3500!

2. DC to DC Charging Makes the Best Use of Your Vehicle’s Power

Now, let’s look at our second power generation source using Direct Current (DC) from our towing vehicle while we’re driving.  In the back of our truck, we have a 50A DC to DC Charger that efficiently charges up the 100Ah LiFePO4 DuoHeat battery which powers our 12V ICECO Fridge Freezer.

This 50A DC to DC Charger with MPPT can also handle a solar panel input. So, when we’ve been parked in the same place for more than a few days, we can keep this battery topped up with our 400W portable panel without having to start the truck engine.  Once our 100Ah DuoHeat battery is fully charged, the 50A DC to DC charger will trickle charge our vehicle’s starting battery, so we never be left out in the boondocks with no way to crank the engine up.  

And…here’s a simple trick!  A $10 battery switch and some extra cables gets us a whole lot more flexibility with our off-grid system.  We can switch the DC to DC charger to charge our house batteries in our camper, rather than the fridge battery in our truck, whenever we’re hooked up and driving.  In just a few hours, our house batteries can be recharged and ready to go. This is particularly helpful in the late autumn, winter and early spring when our fridge doesn’t run as much. This is also the same time of year with lower solar gain, so it’s great to have this option to move energy around to where we need it, when we need it.  With a couple of Renogy ONE Core monitors, we can easily see which part of our system needs to be charged up.

Here’s one more trick to this puzzle that we just love!  If we plug the 400W portable panel into the DC to DC Charger with MPPT and have our 2 x 100Ah LiFePO4 PRO batteries (camper battery bank with self-heating function) selected, we can transform our 200W solar system into a 600W solar array – and this charges up our system in no time flat!

Earlier, we mentioned that we cannot have both solar arrays going into the same charge controller at the same time.  But in this arrangement we have 2 charge controllers going to the same battery bank, which is a great way to combine different solar array wattages.  Yes, it’s that simple!

Here’s our solar system diagram which illustrates the whole scheme – note that the truck and camper sides of the system are connected via a quick connect / disconnect Anderson plug. 

3. Charge While Connected to Shore Power

While we rarely need it, we occasionally find ourselves wanting a little bit of a power boost, especially if we aren’t planning on driving for a couple of days and Mother Nature has been dumping rain or snow on us.  During extended bouts of wet weather, it’s great to have the option to plug in and get charged up.  

Most RV’s come with a converter which charges house batteries with an Alternating Current (AC) power source, but our camper was constructed in 1957 before converters were really a thing.  We could have installed a converter, but since we rarely use this charging method, we chose a small 20A AC to DC charger that is compatible with our Lithium Iron Phosphate batteries.  It simply plugs into our outlets connected to shore power and clips directly onto the battery terminals.  It charges up our 2 x 100Ah LiFePO4 PRO batteries in just a few hours from around a 30% SOC to a full 100%.

Another option for AC charging when converting a vehicle that doesn’t already have a built-in converter is an inverter charger.  Check out our video installation on this school bus conversion, aka “Skoolie” for details!

It’s rare that we even need this option – maybe 1-2 times in the winter or during really terrible weather – but it’s always great to have this as a backup just in case because we have never carried a gas powered generator, and never will.  

So go ahead and flex your system to make sure you’re taking advantage of every charging option that you might need.  To size a system that’s right for you, check out our updated 2025 Solar Sizing Worksheet, that will walk you through every step of the way.  Now, get out there with confidence…and options!

☝Remember to use our link AND promo code CANLIFE at checkout to save a bundle on Renogy components!  And, of course, holler back with questions.  We love to help!

This blog contains affiliate links. When you use our links and promo code to make a purchase at renogy.com, you get a sweet discount and we get a small commission. In addition to volunteering our time, we donate a portion of our affiliate proceeds to non-profit organizations that support youth education/development, sustainability, health, environmental education, and access to outdoor adventure. Discover more about us and how we've been traveling with solar power since 2012 -- all over the North American continent.