When living off-grid in a bus, truck, van, RV, or any converted vehicle, the electrical system is one of the most important systems in your conversion.  What type do you choose? How many batteries do you need, and what kind?  If you plan to use solar to power your appliances, you need to know how many panels will be necessary to maintain and replenish your battery bank. 

You must also determine what charge controllers to use and select a brand. With all the false information on the internet, you have to decide what’s true and what is just internet misguidance. 

I’ve had many people bring me buses they converted and ask me to “fix” them because they watched some YouTuber who doesn’t know what they are doing. Many people out there think they know how to do a conversion and charge people to do the work, but they have very limited experience in the correct way to do it. 

So, let’s break this down. First, I’m not paid by any company to endorse their brand. I use the brands because I have tested them and know they work in my conversions. We just finished bus build number 217 as I’m writing this article. I have quite a bit of experience converting both OTR (over-the-road) buses and school buses.  

We use as much 12 VDC as possible. We use DC electric refrigerators, LED lights, and DC-propane appliances. Our stove/oven combinations use propane with a 12 VDC ignition source, and our water heaters use a combination of 12 VDC and propane. 

Our in-house-built pellet/wood hybrid heating stoves, use a 12 VDC auger to feed the pellets, and we use 12 VDC fans and pumps for the hydraulic systems. 

Our clothes washer and hydronic dryer use 120 VAC for the agitation and tumbler. They can wash a load of eight pairs of jeans with as little as 500 Watts of electricity. 

The clothes dryer uses 120 VAC to turn the tumbler and hydronic heat to dry the clothes. It draws only 100 Watts. If hydronic heat isn't available, the dryer can also use propane. The microwave, if the coach has one, is also 120 VAC.  

Using as much 12 VDC as possible keeps the power loss of converting DC to AC as minimal as possible. A good example is running a 120-volt AC refrigerator with an inverter that draws 7 Amps of AC at 120 Volts. It will draw 49 DC Amps from the battery with a Xantrex 458 inverter. The inverter's DC draw will vary depending on the brand and its voltage, but the refrigerator we use runs on 12 VDC power and draws only 5.5 Amps.

You save 43.5 Amps per hour using 12 VDC over inverting DC to AC power. Some may argue that using a 48 VDC inverter is more efficient and uses fewer DC Amps but still more than double what the DC refrigerator draws. 

So, by not having to convert from DC to AC except for a couple of heavy loads, you can really stretch out your power needs. In one conversion, we call “Big Dog,” we have 1800 Watts of solar power, 1000 Watts of wind power, and a 550 Watts hydro generator. On most full sunny mornings, our batteries increase from 12.1 VDC morning voltage up to 14.1 VDC within two hours. 

There are several advantages of lithium batteries.  They can discharge down to 20% of their capacity, whereas lead acid batteries can only go down to 50%.  Many lithium batteries are guaranteed to still have 80% of their charge after ten years of normal use, whereas lead acid batteries usually last only about half that time, and only if they are well maintained.  Lithium batteries are less than half the weight of lead acid batteries and can be mounted inside the living compartment. You can also do this with AGM batteries, but you cannot do this with lead-acid batteries due to the off-gassing.   

The other advantage is that lithium batteries can be mounted in any orientation in the bus: right-side up, lying on their side, or upside down. Many people like those features and are willing to pay the price, which is a personal preference. The one drawback to lithium batteries is that they do not like the cold, so many people up north locate them inside the bus in a warm environment or they now have lithium batteries that have a heating element. 

When we design a bus, we determine the customer’s electrical system needs in total Amps and then add 40% for cloudy and windless days. This gives us a baseline from which to work. For the DC side, we use an AC/DC master panel with monitoring capabilities and circuit protection.  

We have a DC-to-DC charger to tie the coach batteries into the house system for charging. When the coaches’ start batteries get down to a preset voltage, the solar system will charge them back to a preset voltage and then disconnect from the coach batteries. We do the same thing for the generator start battery. We like to use USB chargers all through the bus to keep the lifesaving personal devices charged. 

Here are some interesting facts about the Big Dog bus: When we spent the entire winter in Wickenburg, Arizona, we used only around 1000 Watts of power in 24 hours—that’s it. That was with all living systems, including TV, satellite, refrigeration, lighting, appliances, and the water system. The batteries never dropped below 12.0 V between wind and solar; they stayed charged no matter how much we used the system. To keep your system efficient, we use as much 12 VDC as possible. 

One thing you can do to maximize your energy usage with solar is to clean your solar panels often. To make this easier, we install a sprinkler system on the roofs of our buses. We use a quick connect on a faucet to plug a water hose into, and then you can rinse the panels with water from the onboard water system as needed to keep them operating at maximum capacity.

This makes cleaning panels very easy as you don’t have to climb a ladder with cleaning supplies in your hands, where the roof or the ladder can be slippery and, hence, dangerous when wet, as everything is already on the roof. We have an anti-freeze valve, this valve automatically dumps the water and shuts off the flow when the water pressure is released on the water line that feeds the roof-mounted faucet, just in case the temperature gets down to freezing at night. This is so you don’t have to constantly watch the ever-changing weather.

The bottom line is that with the current components available and with solar panels and Lithium batteries much more prevalent now, you can run any RV or converted vehicle appliances totally on electric. Unless the sun stops shining completely two or three days in a row, you should never need to plug into shore power or run a generator. Unless you like parking under trees, and there is a solution to that as well: portable solar panels, which some folks use.