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One of the objectives of this lifestyle is to get off the beaten path a bit more. Going off the grid. To do that we wanted to go solar.

The majority of RV’s stay in established campgrounds with “full hookups”. That is, power, water and sewer connections. It makes the RV much more like a house when you have all three. You can run air conditioners when it’s hot, microwaves for easy cooking and so on. For many people, this is camping and it’s fine for what it is. But we didn’t embark on this lifestyle to stay in a substitute for a suburban house. We wanted to stay out in places far from the crowds and much closer to nature than you find with the typical commercial campground. To do that means you give up the full hookups. The RV has fresh water and waste tanks and we can stay out for about a week before we need a re-fill on the water. Power on the other hand is a bit harder.

Most of the systems in an RV run off 12V battery power. Power hogs like air conditioners and microwaves generally need 120VAC or “shore power”. The fridge runs on propane when off grid and the furnace and water heater do as well. The water pump and all the lights run off 12V battery power. In newer RV’s all the lights are LED’s so they are very efficient. So far so good if you have enough battery capacity. So what does the average RV come installed with? You guessed it, not nearly enough. One, maybe two deep cycle “marine” batteries. If you have to run the furnace all night you’ll probably wake up to a cold RV and dead batteries.

So to spend any time out in the “boonies” you need more battery capacity. The second issue to address is you need a way to charge them back up. With shore power it’s easy. The “converter” installed in most RV’s is nothing but a battery charger and it keeps the batteries topped off continuously. Once off shore power you need another source. The first choice of many is a generator and that works well. We have a small Honda generator to serve that need. But running a generator every day for an extended period gets old. That’s what we had on the motor home and we wished for a better solution. Solar is becoming the practical answer for RV’ers that want to get off the grid. For us, it was the solution that made the most sense.

The following segments will get a little technical but stay with it. It’s not too bad. The image below shows most of the parts needed for a full system.

In order to go solar you need a place to store all that free energy from the sun. A battery is the logical choice. A lot of batteries if you want to survive some cloudy days. They are rated in amp-hours of capacity. So a 100 amp-hour battery can supply 100 amps for an hour before being totally discharged. Or 10 amps for 10 hours. But as I explain below, you don’t really get to use all that if you want your batteries to last.

Batteries come in several types. The typical car battery is a lead-acid “wet cell” technology. It’s been around for decades and works very well. It has a couple of drawbacks however. First it’s heavy. It’s made of lead. Second, even a deep cycle battery can only safely be discharged to 50%. Any more than that and the battery life will be shortened. Do it too many times and the battery will be ruined. So for a 100 amp-hour battery, only 50 amp-hours are usable. 6V golf cart batteries are a little more robust but the 50% discharge limit still applies. So a battery bank of lead-acid batteries was not our choice. Next best option is Absorbed Glass Matt technology or AGM for short. These are maintenance free and are still the choice for many off grid applications like on sailboats. Still very heavy but much more robust than a lead acid battery. But because of the weight, we didn’t choose them either. I wanted something better.

Lithium Iron Phosphate or LiFePO4 is a relatively new technology for deep cycle batteries that have a lot of benefits for off grid applications. First, you can discharge them down 80% and they bounce right back with a recharge. Second, they weigh significantly less than lead-acid or AGM batteries. Third, the new offerings out right now have integrated battery management systems built right into the battery case. It won’t let the battery discharge too far or too fast. It will also shut down if the battery is in an over or under temperature situation. The big drawback still for Lithium is the cost. A single 100 amp-hour battery is roughly four times the cost of an equivalent amount of usable amp-hours in a lead-acid battery. Despite the cost, this is what we chose. Over the lifetime of the batteries, the Lithiums are actually competitive since they last far longer than the lead acid batteries. Plus we saved a lot of added weight to the RV. The six batteries gives us 600 amp-hours of capacity and since we can use up to 80% of that, 480 amp-hours of useable capacity. 600 amp-hours of lead-acid batteries would only net 300 amp-hours for example. The brand we chose was Battle Born batteries out of Reno, NV. They’re made here in the USA. The folks there were super helpful with the system design and expediting parts when needed. They also supplied beefy 1/0 AWG cables to wire the batteries up with. I bought the Victron components mentioned below from them as well so they sell more than just the batteries. It’s a relatively new company and they are very customer focused. Really good folks to work with.

Solar panels have been around for a long time. The technology is pretty robust and many manufacturers will warrant them for 25 years. There are two types of panel technology out there, mono-crystalline and poly-crystalline. Both refer to the type of silicon wafers used to produce the panel elements. The mono type put out a little more energy than the poly given the same area but are also a bit more expensive. I decided to go with the mono-crystalline technology for its higher efficiency.

Panels come in many sizes but 100W panels are pretty common. I chose to go with that size and used panels from Renogy Solar. They are available from Amazon and were available with Prime shipping. I went with eight panels for a total of 800 Watts. The installed panels are shown in the image at the top and below.

Now that we have the batteries to store energy and solar panels to generate energy we need a way to get that energy in and take energy out properly. We need some controllers. The complete install is shown below. First up is the inverter/charger and is the large blue box on the left in the photo below. It charges the batteries when we’re hooked to shore power or when we hook up a generator. It’s an intelligent three stage charger that knows how to charge lithium batteries. You need that. I chose the Victron brand based on reviews and prior knowledge in the marine segment. The second function it performs is as an inverter. This takes energy out of the 12V DC battery and converts it into 120V AC that you need to run the microwave or countertop appliances like coffee pots, blenders, etc. I bought the 2000W version which means it can supply 15 amps of 120V AC or the equivalent of one household circuit. Enough for what we would use.

The second controller is the solar charge controller and is the second blue box next to the inverter. This box takes the current from the solar panels and converts it to the correct voltage to charge the batteries. They need a specific voltage for each of the three stages of charging: bulk, absorption, and float. This is also from Victron and is a MPPT controller. This stands for multiple power point technology which is the more advanced controller technology and is also more efficient than the PWM type controller.

Each solar panel puts out around 18.9 volts DC at 5.3 amps. I decided to wire them in a series-parallel combination. Two panels in series, parallel with two panels in series, etc for a total of eight panels. This gives me an operating voltage of 38 V DC which is more efficient for the MPPT controller. The combined current of four of the series combo’s is 4 x 5.3A = 21.2 amps at 38 Volts DC. The MPPT controller then steps the voltage down and the current up to what the batteries can use, around 14.4 volts. The current gets bumped up to 50+ amps DC at full sun.

The other components mounted to the back wall are disconnect switches to take the batteries and solar off line when needed for maintenance. There are also inline fuses to protect from an over current situation. On the far left is a device called a DC shunt that measures the current flow into and out of the batteries. It uses that along with the battery voltage to show the state of charge on a remote monitor panel.

One nice thing about the solar charge controller and the battery monitor is both are Bluetooth enabled so I can monitor everything from my iPhone.

As we mentioned in the previous post, we’re doing some configuring to the new rig. This is one of those and a big one. Also, as full time RV’ers, doing an install like this on the road can be a little more difficult. We’re living in the rig while I’m re-wiring things. We decided to do this while in South Dakota for our “annual” visit. Having access to the big box home improvement stores was key. As was having a campground that allowed us to make these fairly major changes.

This was a fairly complicated install. If you don’t have any experience designing and wiring a system like this, doing this as your first one would not be a good idea. Plus, some of the install deals with 120V AC circuits in the RV so unless you’re very experienced with that, get some qualified help. My intent was to de-mystify an install like this and to clarify some of the concepts. Even if you have someone else do the entire install, it helps to understand what they’re doing.

We don’t have enough time off grid with the system yet to know if this is the right capacity or not. I have room to expand if need be but I don’t think it will be necessary. We’ll be testing it pretty thoroughly in the near future as we head up into the Canadian Rockies for an extended period. Much of this will be off the grid. And after all, that’s why we did this install in the first place.

I have created a list of all the components used in the resources page. You can access that here.

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