If you’ve been researching inverter options for your RV, boat, or off-grid system, you’ve likely come across the term split phase inverter. But what exactly does that mean, and do you really need one? For most RV and marine applications, the answer is no—but there are some situations where split phase makes sense. Let’s break it down.
Split phase power is the standard method of residential electricity delivery in North America. The system starts with a transformer on the utility pole or ground that reduces high-voltage distribution power down to household levels. That transformer has a 240-volt coil with a center tap, which “splits” the system into two equal 120V halves. The center point becomes the neutral, while the two outer ends serve as the “hot” wires.
This arrangement allows homes to power both everyday 120V circuits and higher-demand 240V appliances such as ovens, dryers, well pumps, and EV chargers.
By contrast, many other countries supply a single 230V line-to-neutral connection without the split to all appliances.
Both systems have their pros and cons, but they are not directly interchangeable.
Single phase power is the simplest form of AC electricity delivery. It uses just one alternating voltage waveform, supplied by a single “hot” conductor and a neutral. The voltage rises and falls in a smooth sine wave—typically 120V in North America or 230V in many other countries.
Both single phase and split phase systems use alternating current (AC), but the way the voltage is delivered is different.
Each leg of a split-phase system is still single phase. There’s no such thing as “two-phase” in this context. The benefit of split phase is simply that you get two single-phase supplies that can also be paired to provide 240V.
In short:
In residential homes, split phase is common because of the need to power large appliances. But even in a house, most outlets and devices only use 120V. The 240V side is reserved for high-demand appliances.
When you plug your RV or boat into an electrical pedestal, you’re plugging into a split-phase power system. However, your RV or boat will use it differently depending on its power design:
However, most RVs don’t actually use the full 240V capacity. Instead, the two 120V legs are split across different circuits to allow more power-hungry devices—like multiple air conditioners—to run simultaneously.
Very few RVs or boats have true 240V appliances installed.
A split phase inverter mimics the 120V/240V phases provided off the pedestal when you’re off-grid. It’s an inverter that takes DC battery power and produces two 120V AC outputs that are 180° out of phase, plus a neutral.
Most RV and boat inverters provide only one 120V AC output.
Just like the grid’s center-tapped transformer, a split-phase setup gives you both:
That means your RV or boat can mimic the same power scheme as a North American home electrical panel, making it compatible with household appliances that expect 240V.
For most RV and marine systems, a regular (single-phase) 120V inverter is more than enough. Nearly all onboard equipment—air conditioners, outlets, chargers, and galley appliances—can run on standard 120V power.
Even if your rig has a 50-amp shore power connection, you don’t automatically need split phase. In that setup, the two legs can be in phase and simply provide more current capacity at 120V. A properly sized 120V inverter (or two working in parallel) can cover this without creating a true split-phase system.
You only need a split phase inverter if you plan to power appliances or systems that specifically require 240V line-to-line, such as:
In these cases, a split-phase inverter is the only way to provide 240V power when running off your battery bank and solar array. Without one, the appliance would only work when connected to shore power.
It’s also worth noting that sometimes you don’t need to make the entire RV or boat split phase. For example, a customer of ours uses a single 230V inverter programmed to 240V 60Hz just to power a car charger. In that setup, the rest of the RV stays 120V, while the one appliance gets the 240V it needs.
If you do need split phase, there are a few ways to get there:
Some inverters, such as some Sol-Ark inverters, can provide true 120/240V split-phase power from a single device. These are generally higher voltage inverters operating at 24V or 48V.
The advantage here is simplicity—only one inverter is needed. However, load balancing can still cause problems. If too much power is pulled from one leg, the inverter may shut down the entire system before you ever reach the maximum rated power. This is especially important to consider in RVs, where air conditioners and other heavy loads might stack on a single side.
With products like the Victron MultiPlus or Quattro, you can program two inverters to operate in split phase. See our split phase programming guide for details.
It’s important to note that not all inverters can simply be wired together for split phase—they must be designed to communicate and be programmed correctly. Attempting to hook two inverters together without proper setup will damage them.
One limitation of paired inverters is that each 120V leg is still limited by the maximum output of a single inverter. For example, if each inverter can output 3,000W, then each leg is capped at 3,000W. This means the system could trip offline even before you hit the combined total power rating, a common frustration for RV owners trying to run multiple air conditioners.
We’ll cover ways around this in the autotransformer section below.
An autotransformer can play a critical role in making split phase systems more flexible and reliable. These devices can usually be configured to accept different inputs—120V, 230V, or 240V without a neutral—and provide a center-tap neutral, essentially mimicking the way utility transformers work.
Autotransformers can be added to split-phase inverter systems to improve operation or even create split-phase from single phase 120V inverters.
Autotransformers also help with load balancing by allowing more power to be pushed to one leg when needed, while still pulling evenly across both sides of the inverter. This means inverters configured for split phase (either a single split-phase unit or paired inverters) can more easily handle high-demand appliances on a single 120V leg without tripping offline.
In RV and marine systems, this flexibility is often the difference between frustration and smooth operation.
As a recap, running split phase isn’t always simple. Here are a few things to keep in mind:
One of our customers, the Getaway Couple, installed a full off-grid system in their RV with six Battle Born Batteries, eight solar panels, and two Victron MultiPlus inverters configured in split-phase. This setup allowed them to comfortably power all their onboard systems while boondocking, including multiple air conditioners, with full redundancy in case of an inverter issue.
Most of our off-grid home customers also choose to use a split-phase setup as it mimics standard residential power coming from the utility.
For most RV and marine systems, you don’t need a split phase inverter. A single-phase 120V system is simpler, more efficient, and fully capable of running everyday appliances. But if you plan to power a true 240V appliance—like a dryer, stovetop, large electric motor, or EV charger—then a split-phase inverter (or a dedicated 240V inverter for that appliance) is essential.
Not sure what’s right for your setup? Our technical team is here to help you design the ideal power system. Contact us today to discuss your needs.
What is a split phase inverter?
An inverter that outputs 120/240V split phase power, mimicking North American residential power.
How does split phase differ from single phase?
Single phase provides one line-to-neutral voltage (120V or 230V). Split phase delivers two 120V legs that can combine to provide 240V.
Do I need a split phase inverter for solar power?
No—solar panels feed into your battery system. The inverter determines the type of AC output.
Can I run a 240V appliance on a single-phase inverter?
Not directly. You’d need either a split phase inverter or a dedicated 240V inverter for that appliance.
What’s the difference between split-phase and three-phase?
Split phase is still single phase (two legs 180° apart). Three-phase has three waveforms spaced 120° apart, used mostly in industrial power.
Can I pair two inverters to make split phase?
Yes. Many Victron inverters can be paired to provide 120/240V split phase output.
We know that building or upgrading an electrical system can be overwhelming, so we’re here to help. Our Reno, Nevada-based sales and customer service team is standing by at (855) 292-2831 to take your questions!
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