What Size Inverter Do I Need For My RV or Van Conversion?
With so many choices on the market, it can be challenging to determine which Inverter size you need for your RV or van. By the end of this short guide, you’ll know how to make an educated decision when purchasing an inverter.
What does an inverter do?
An inverter takes DC (direct current) from a Battery Bank, and converts it into AC (alternating current) to supply power to common household appliances (like TVs, microwaves, etc.)
Deciding which inverter is right for you only takes a few quick steps. Let’s get started!
Overview
- Taking inventory your 120v appliances
- Performing simultaneous load calculations
- Consider your battery bank – Inverter/Chargers
- Confirming inverter voltage
- Identifying 30a or 50a service
- Choosing an onboard or portable generator
- Using the RV Inverter Calculator
Taking inventory of 120V appliances in your RV or van
To determine which size inverter is right for your RV or van, we first need to take inventory of the 120v household appliances you plan to use.
Start by making a list of each 120v appliance you plan to use off grid. Be sure to also note the wattage of each appliance.
Wanting to power a split phase 120/240v service with an inverter? Hang tight, we’ll cover this later.
Performing simultaneous load calculations
Once you’ve listed all the appliances you plan to use, the next step is deciding which appliances you might want to use simultaneously.
For example, you may want to watch TV while brewing a pot of coffee or cooking dinner in an Instant Pot and charging your laptop all at the same time. These would be considered simultaneous loads.
So, we need to add up the wattage of each of these appliances to arrive at our Simultaneous Load Total.
If you have a 120v (residential-style) refrigerator, be sure to include this in your simultaneous calculations as well.
Check out our Inverter Calculator to easily determine your Simultaneous Load Total.
Consider your battery bank
Your battery bank will have specific requirements of your inverter, so at this step, we need to review a few details.
Battery bank voltage
Most inverters are designed to accommodate a specific battery voltage. At this step in your calculations (or using the RV Inverter Calculator), select the voltage of your battery bank: 12v, 24v, or 48v.
Do you also need a battery charger?
Many inverters have built-in battery chargers. These are referred to as inverter/chargers (or hybrid inverters), and are perfect for those who also want the ability to charge their battery bank from shore power (e.g. with an RV park power post, a household outlet, etc.) or from a generator.
When connected to shore power, 120v AC (or 230V AC, for many countries outside North America) will pass through the inverter and power all 120v loads. Further, if a surplus of power is available, any extra will go towards charging your battery bank.
Besides just having the ability to charge your batteries from these sources, inverter/chargers such as the Victron MultiPlus and Quattro series have some incredible additional features. These include “Power Assist,” or the ability to supplement (or assist) shore power with power from your battery bank to power loads that are larger than what the shore power or generator source may be able to handle alone.
Diving into the specifics of all the features for these inverter/chargers is beyond the scope of this guide. For more info, check out the datasheets and manuals for the MultiPlus and Quattro models.
Up front, an inverter/charger will be a larger investment than just buying an inverter alone. This said, the cost is well justified if charging your batteries from a shore power or generator source is a requirement.
Confirming inverter voltage
When it comes to Victron inverters, you’ll find many options available for both 120v and 230v. For the most part, if you’re planning to only use your inverter in North America, be sure to use a 120v model.
Identifying 30a or 50a service
Service refers to the power that your RV or van conversion is rated to accept. Most RVs in North America are rated for either 30 amps or 50 amps.
Many smaller travel trailers, class Bs, and van conversions are rated for 30a. Larger fifth wheels and Class A coaches are typically rated for 50a.
Note: this is just a general rule of thumb. Be sure to consult your user manual if you are unsure about your RV’s service rating.
Why knowing your 30a or 50a service status matters
This is an important question, mainly for one BIG reason:
A 30a service only requires single-phase 120v, while a 50a service requires 120v/240v split-phase in order to operate at full capacity.
So, if you have a 30a service, you’ll be fine with a single 120v inverter. This will supply power to your main breaker.
However, if you tried to use a single 120v inverter in a 50a service (with one exception – noted below), only half of your appliances and outlets would be live. This is because it would only be providing power to one main breaker (meaning one half of your AC panel).
For a 50a service, you have (2) main breakers, so you’ll either want (2) 120v inverters configured in split-phase, or (1) MultiPlus 2×120, an inverter/charger that will deliver (2) legs of 120v to power both main breakers and provide power throughout your RV.
Do you have an onboard or portable generator?
The differentiation in this section is between inverter/chargers with (1) AC input, such as the MultiPlus, and models with (2) AC inputs, like the Quattro. While the single input MultiPlus has the ability to seamlessly transfer between shore power and inverter, the Quattro has an extra AC input and transfer switch for applications that include onboard or stationary generators.
To keep things simple, there are really only three possibilities here.
- If you have a portable generator and plug this into your shore power inlet, you’ll be just fine with a MultiPlus.
- If you have an onboard generator with an Oem Transfer Switch already in place (which will be the case for any RV with a factory-installed onboard generator), you can use the OEM transfer switch with a MultiPlus. Or, you can remove the OEM transfer switch and go for a Quattro.
- If you’re planning on installing an onboard generator in an RV retrofit or camper conversion, the dual AC input Quattro inverter/charger would be a great option.
Using the RV Inverter Calculator
If you made it this far, congratulations! You can now use the power of knowledge to make an educated decision in your quest to acquire an inverter. If you’re still a little unclear, or want to double check your work, we encourage you to check out our free RV Inverter Calculator. Simply answer a few questions and you’ll get a personalized recommendation for the inverter that will work best for your particular needs.
With all of the available options, choosing the right inverter can feel overwhelming at first. We hope that this guide has empowered you to better understand the considerations you’ll want to make before investing in an inverter.
