Why 12V DC Systems Still Make the Most Sense for RV and Van Conversions
One of the most common questions we get from van builders and RVers is: Should I go 12V, 24V, or 48V for my house battery bank? The internet is full of influencers promoting 48V all-in-one (AIO) systems—combined solar MPPT, inverter, and charger units—claiming they’re more “efficient,” run cooler, and require smaller wire gauges.
Some of that is technically true.
But here’s the bigger truth: an RV is one of the least efficient living spaces you can design. It’s a one or two-bedroom apartment on wheels, wrapped in sheet metal and basic insulation that wouldn’t meet 1980s building codes. You’re burning diesel or gas to move thousands of pounds down the road, and trying to heat or cool an unsealed box that leaks thermal energy in every direction.
Trying to optimize for wire thickness or inverter efficiency in that context? It’s a bit like installing racing tires on a cement truck. You’re solving a problem that doesn’t really matter.
1. RVs Are Inherently Inefficient. Don’t Chase Marginal Gains.
Let’s be honest: in a vehicle that gets 8–12 MPG and leaks air through every panel seam, the idea that saving a few amps by switching to 48V is a game changer is misleading. Thermal losses, fuel inefficiency, and HVAC power draw far outweigh any marginal electrical gain. Your inverter might be 2% more efficient on 48V, but your rooftop AC is still chewing through 1,500W and your uninsulated walls are dumping that cold air into the desert heat.
2. Modularity Beats All-in-Ones in the Real World
A big issue with 48V AIO systems is that they are exactly that: all or nothing. If your solar charge input fails, your whole power system could be crippled. With a 12V modular system, you can isolate issues and keep the rest of your system running. A failed PWM solar controller? You can bypass it with a direct connection in a pinch. Need a new inverter? Pick one up at nearly any auto parts store.
Try finding a replacement 48V AIO inverter/charger with custom firmware in rural Idaho.
3. 12V Systems Are Safer and Easier to Work On
48V systems, especially on the solar input side, often run 100–150V DC. That’s well into hazardous voltage territory, especially for DIYers with basic tools and no protective gear. A wrong move on a 48V system can mean arc flashes or serious shock. With 12V, mistakes are usually survivable—and fixable.
4. Compatibility and Support
Most RV and van appliances—fridges, fans, lights, pumps—are built for 12V. If something breaks, replacements are easy to source and install. Mechanics, RV techs, and even roadside assistance crews understand 12V. Ask them to troubleshoot a 48V solar MPPT that’s part of an integrated touchscreen-driven AIO, and you’re on your own.
Bottom Line
Don’t let the hype over high-voltage systems distract you from what actually matters in an RV: simplicity, safety, and reliability. RV life is full of bumps—literally. Things break. Roads shake gear loose. When you’re 50 miles from the nearest town, the last thing you need is a fragile, high-voltage AIO that shuts everything down when one chip fails.
A well-built 12V modular system may not win the efficiency argument on paper—but it wins where it counts: in the real world, off-grid, when you’re your own electrician, mechanic, and power company.
In RVs, simplicity is efficiency. Stick with 12V.