If you are interested in boondocking or running your RV fridge off grid, it is important to make sure you have what you need to keep your batteries charged up. So how much solar do you really need to run an RV fridge? We are full-time RVers who have been traveling full time in our fifth wheel since 2022 and spend about 50% off grid. Given the amount of time we spend boondocking and dry camping and our power consumption, we invested in a sizable solar system for our RV. With 1700 watts of solar panels on our fifth wheel and 600 amp hours of lithium batteries, we are able to run any appliance we’d like, including our residential refrigerator and air conditioner. In this article, we help you discover how much solar is right for you based on your RV setup and what you need to keep your fridge running and your food safe!
The Basics of Solar Power
In order to know how much solar power or what kind of solar setup you might need in your RV to run your RV fridge or other appliances, it is important to first look at the basics of how solar power works and the formulas and calculations you can use to determine what components you might need.
If you’re already familiar with the basics of solar power, jump here for calculations and recommendations for running your RV or residential fridge on solar power.
What is Solar Power?
Solar power is exactly how it sounds; harvesting energy from the sun and storing it in batteries to use immediately or at a later time (over night).
You’ll typically have an inverter for your RV that turns the power in your battery bank from a lower voltage (12, 24, 48) to 120 volts to power household appliances.
To know how much solar you need to power an RV fridge and any other appliances you’re interested in, first you need to understand a bit about electricity, which we dive into next!
Watts, Volts, and Amps
To figure out how much solar you need to run an RV fridge, you first need to understand watts, volts, and amps.
To grasp the basics, try thinking of electricity as water flowing through a pipe. Watts (W) represent the power or energy used, which you can think of as the overall volume or amount of water moving through the pipe. Volts (V) measure the electrical pressure, which you can think of as the water pressure, and amps (A) indicate the rate of electrical flow, or how fast the water in the pipe is moving.
- Watts (W): Watts represent the amount of electrical power consumed or produced by an appliance. In our case, it signifies the energy required to run an RV fridge. Typically, an RV fridge consumes around 100-300 watts of power when running. This value can vary depending on the size, efficiency, and specific features of your fridge.
- Volts (V): Volts refer to the electrical pressure that determines how forcefully electricity flows through the system. Most RVs operate on a 12-volt system, meaning the electrical appliances inside, including the fridge, are designed to work with 12 volts of power. It’s important to note that some larger RV fridges may require 24 volts or more, which might necessitate additional equipment. A residential refrigerator uses 120 volts and requires an inverter.
- Amps (A): Amps measure the rate at which electricity flows in a circuit. To calculate amps, you can divide the watts by the volts. For example, if your fridge uses 120 watts and operates at 12 volts, the current draw would be 10 amps (120W ÷ 12V = 10A).
You’ll often hear someone say they have “400 amp hours” of batteries. If they have 12v batteries, that would mean they could have a 400 amp draw at 12 volts on their batteries for 1 hour to bring them down to completely empty. Many batteries will cut off prior to being completely empty, but you get the idea.
Formulas & Calculations
You can use the formula below to understand how volts, amps, and watts interact.
- Volts x Amps = Watts
- We have 600 amp hours of 12 volt batteries. 12 volts X 600 amps = 7,200 watt-hours of batteries
In terms of available energy, this would be exactly the same as 300 amp hours of 24 volt batteries. Both are 7,200 watt hours.
As we dive deeper, it is easiest to think in terms of watts and watt-hours.
Depending on YOUR specific RV, volts and amps can vary from another person’s RV, but watts can be thought of as a comparable metric of power regardless of how many volts or amps are being consumed.
AC Power vs. DC Power
Alternating current, or AC for short, is the type of electricity you’ll find in your home. When you plug something into an outlet in your house, that is AC power coming from the outlet. Alternating current does just that. The flow of electricity changes direction frequently. All the powerlines that you see when driving around will be AC electricity as it is more efficient to carry over long distances than direct current (DC) power.
With the exception of driers and a few other specialty electric items (welders, etc.), electric items found in a typical North American house will use 120 volt AC electricity. At a campground, you’ll usually see 50, 30, and 20 amp service (power) at the pedestal. This is because some RVs use 50 amp while others use 30 amp. You’ll see 20 amp power for extension cords or other miscellaneous appliances.
You’ll also hear AC power referred to as “shore power” in the RV community. When someone mentions shore power, they mean plugging their RV into a power pedestal at a campsite, or even “moochdocking” and plugging into an extension cord from a house outlet!
Direct current, or DC for short, is used in applications that are not connected to the power grid. Things like RVs, cars, boats, etc. all use DC power as they don’t always have access to AC. Direct current is also aptly named. It sends electricity in a constant direction.
DC voltages are typically lower (common voltages for RVs are 12v, 24v, and 48v) which means higher amperage. We’ll talk more about amps in a bit. If you get electrocuted by direct current electricity, it doesn’t “let go” like AC power will, which is all the more reason to be extremely cautious when dealing with electricity.
What Else Can Solar Power?
This is somewhat of a trick question. In every off-grid solar setup I’ve seen or built, solar doesn’t directly power anything.
Solar charges the batteries, and the batteries provide all power.
To understand what else solar can power, you need to know if there is an inverter. If you aren’t familiar with the function of an inverter, take a minute to read our article on what an RV inverter does.
If there isn’t an inverter available, then you’ll only be able to power items that run on DC power. This includes an RV fridge, lighting, water pump, fans, TV, etc.
If you do have an inverter, then you’ll be able to power just about anything you would ever want or need off-grid. This would include a microwave, residential refrigerator, dishwasher, electric water heater. The list goes on.
As long as you have enough solar to replenish the power you draw from your batteries, you’ll be living the good life!
RV Solar System Setup Basic Components
Now that we have discussed a bit about how solar power works and what all the terms mean, let’s take a deeper dive into the components you will need to install to run the fridge in your RV off solar energy.
First, you need a reasonably sized battery bank to store power overnight or when a cloudy day or two comes along.
Below are the main types of batteries. I’ve also included a chart that recommends a minimum battery bank size to power your RV fridge and other appliances.
- Lithium Iron Phosphate Batteries: Also known as LiFePO4 batteries, these are lightweight, compact, and have a higher energy density compared to lead acid batteries. They provide a consistent voltage output and maintain their performance throughout the discharge cycle. They are also maintenance-free, require no watering, and can be discharged to a lower state of charge without risking damage. Additionally, they have a higher tolerance for temperature variations and can handle high charging and discharging rates more effectively.
- Lead Acid Batteries: The traditional and widely used battery technology. They are available in two main types: flooded lead acid and sealed lead acid (AGM and gel) and are relatively affordable compared to lithium batteries.
- Flooded lead acid batteries require regular maintenance, including water replenishment
- Sealed lead acid batteries are maintenance-free.
- Lead Acid Batteries can handle deep discharges and high current demands, making them suitable for off-grid applications. They are also readily available and can be charged using standard RV charging systems. However, they are heavier, have lower energy density, and shorter lifespan compared to lithium phosphate batteries.
If you are planning to buy lead acid batteries, I’d recommend buying deep cycle batteries, which are designed to provide a steady and sustained amount of power over an extended period.
As a rule of thumb, lithium batteries can be discharged down to about 20% while lead acid batteries can be discharged down to about 50%.
With that in mind, here are minimum battery bank recommendations.
|Lithium||4,800 watt-hours||2,400 watt hours|
|Lead Acid||7,200 watt-hours||3,600 watt hours|
We are full time RVers and power a residential fridge. We recently increased our battery bank to 7,200 watt-hours of lithium due to the heavy power draw of our fridge. Keep in mind that if you have a generator and don’t mind using it, you can get away with less battery capacity and a smaller solar array. This allows you to stay within your budget as well.
Don’t let the expense of a solar system keep you from enjoying the beauty of boondocking…there are other options and a portable inverter generator (we love our Generac 3300i) can also do the job!
Solar Charge Controller
Solar charge controllers are a vital part of powering an RV off-grid. These essential devices ensure the optimal charging and protection of your batteries. Next, let’s explore their function, different types, and how they fit into the larger system.
The primary function of a solar charge controller is to regulate the flow of electricity from the solar panels to the batteries. It acts as a gatekeeper, preventing overcharging of the batteries. By maintaining a controlled charging process, solar charge controllers help extend the lifespan of the batteries and ensure efficient energy storage.
Types of Solar Charge Controllers
- PWM (Pulse Width Modulation): PWM charge controllers are the traditional and cost-effective option. They work by rapidly switching the solar panel’s output on and off, regulating the voltage supplied to the batteries. While PWM controllers are efficient for smaller solar setups, they are less effective at extracting maximum power from solar panels when compared to more advanced options.
- MPPT (Maximum Power Point Tracking): MPPT charge controllers are the advanced and more efficient choice. They utilize sophisticated algorithms to track the maximum power point of the solar panels, continuously adjusting the voltage to ensure optimal charging. MPPT controllers can significantly increase the power output of solar panels, especially in situations where the panel voltage is higher than the battery voltage.
By selecting the appropriate solar charge controller type based on your RV’s power requirements and solar panel configuration, you can maximize the energy harvest, improve battery life, and ensure a reliable off-grid power supply for your adventures.
We use a Victron MPPT charge controller and it has served us very well!
Solar panels are one of the more important parts of an RV solar system. Without them, it is difficult to generate any solar power! All jokes aside, solar panels allow you to harness the sun’s energy.
From experience, I’d recommend having between a 2:1 and 3:1 ratio of solar watts to 12v amp hours of batteries.
We have 600 amp-hours of batteries, so between 1200 and 1800 watts of solar power is enough power for most use cases.
If you want to think about your batteries in watt-hours, I’d say 200 watts of solar for every 1,000 watt-hours of batteries is a comfortable level.
We have 7,200 watt-hours of batteries. That would mean we should have 1,440 watts of solar panels. In reality, we have 1,700 watts of solar panels to provide a little buffer on cloudy days.
An inverter is a device that converts direct current (DC) power from the batteries in your RV into alternating current (AC) power to run household appliances. It allows you to power devices that require AC power while you’re not connected to the grid. If you want to power your RV fridge in “AC” mode when you are not connected to shore power, you will need an inverter.
An inverter charger, on the other hand, combines the functionality of an inverter and a battery charger into a single device.
It not only converts DC power to AC power but also has the ability to charge your RV’s batteries from an external power source, such as a generator or shore power. This feature is especially useful in off-grid scenarios where you may have limited access to electricity and need to recharge your batteries efficiently.
We have a Victron Multiplus II 2,400 watt inverter charger. It has been extremely reliable and provided the power that we need.
If you spend a reasonable amount of time off-grid and want to run more than just your RV fridge, I wouldn’t get anything smaller than the 2,400 watt inverter that we have.
How Much Solar Do You Need To Run An RV Fridge?
I’ll start with the classic answer… it depends!
The amount of solar power required to run an RV fridge depends on several important factors, including the size and efficiency of the fridge, your daily energy consumption, and the solar conditions in your location.
This includes things like direct sunlight, any potential air pollution, and the angle at which the sun is hitting your solar array (it’s much lower in the winter).
What Even Is An RV Fridge?
An RV fridge, also known as an absorption refrigerator, is specifically designed for use in an RV. These fridges operate using a combination of heat, ammonia, and hydrogen to cool the interior. They are available in various sizes and configurations, often offering a freezer compartment alongside the main refrigerator space, but larger RVs will have an RV fridge with a separate freezer.
RV fridges can run on propane gas, electricity, or both, providing flexibility especially if you plan to spend time off-grid.
Pros and Cons of an RV fridge
RV fridges are specifically designed with energy efficiency in mind. They consume less power, making them suitable for off-grid camping or situations with limited electrical supply.
They also offer the ability to operate on propane (LPG), allowing for greater flexibility, especially in boondocking scenarios where electricity may not be readily available.
RV fridges are built to withstand the vibrations and movements experienced during travel, ensuring that your food stays cool and fresh while on the road.
RV fridges aren’t perfect, though.
They generally have smaller storage capacities compared to residential fridges. This may require more frequent grocery shopping or creative storage solutions for longer trips. Generally, you’ll also find that RV fridges take longer to cool down compared to residential fridges, particularly when first starting up or after defrosting.
We’ve had both residential and RV fridges, and find that a residential fridge keeps food cooler, especially frozen food. I’m a sucker for hard ice cream!
Here’s how to go about estimating your solar requirements for your RV fridge:
Running Your Fridge on Electric
Whether you are running your fridge using AC or DC, this approach applies just the same.
To determine the power consumption of your fridge, check the manufacturer’s label, the user manual, or Google for energy consumption.
Multiply the fridge’s power consumption by the number of hours it runs in a day.
- For example, if your fridge consumes 150 watts and runs for 10 hours, the daily energy consumption would be 1,500 watt-hours (150W x 10 hours = 1,500Wh).
If you can’t find the power usage anywhere, getting energy consumption for a similar fridge should do just fine. This will likely range from 100-250 watts. Residential refrigerators can require anywhere from 150-450 watts.
Running Your Fridge on Propane
If you are running your fridge using propane, the electricity consumption will be extremely low!
When running on propane, the electricity is mainly required to power the control panel, interior lighting, and any auxiliary fans or components.
The power consumption of a propane fridge is typically less than 25 watts.
Doing The Math
Take into account the efficiency of your solar system components, including solar panels, charge controller, and inverter.
Solar panel efficiency can range from 80%-85%. Consider losses due to factors like shading, wiring, and temperature. It’s advisable to factor in a buffer of around 20% to account for these losses.
Next you want to determine the solar capacity.
Divide the daily energy consumption by the efficiency-adjusted solar system output to determine the solar panel capacity needed.
- For example, if your daily energy consumption is 1,500 watt-hours and you have a solar system with 80% efficiency, you would need solar panels capable of producing approximately 1,875 watt-hours (1,500Wh ÷ 0.8 = 1,875Wh) of energy per day.
If you had 8 good hours of sunlight per day, this would equate to about 240 watts of solar panels.
Don’t forget about battery capacity.
To ensure continuous power supply, you’ll also need to factor in your battery capacity. Determine the size of the battery bank understanding that you won’t always have sunny days.
Consider the depth of discharge (DoD) to maintain battery health and longevity. A commonly used DoD for lead-acid batteries is 50%, while lithium batteries can handle deeper discharges down to 20%.
Lastly, remember that this is just for your RV fridge. I’d recommend factoring in any other power you’d like to use throughout the day when making decisions about the size of your RV solar system.
When determining the ideal size of the fridge for your RV, next we dive into a few factors to consider.
How to Determine Your Energy Needs & Ideal Fridge Size
- Trip length: If you frequently take extended trips or you’re full-time RVing, a larger fridge might be preferable to accommodate a greater quantity of food and beverages.
- Storage Capacity: Evaluate your storage needs based on the number of people using the RV and their dietary preferences. How much fresh produce, beverages, and other perishable items do you typically carry? RV fridges often have smaller storage capacities compared to residential fridges, so prioritize essential items.
- Power Supply and Energy Efficiency: Assess your RV’s power supply capabilities and the energy efficiency of different fridge models. Larger fridges often consume more power, so ensure your RV’s electrical system can handle the energy requirements. Consider energy-efficient models with high ENERGY STAR ratings to minimize power consumption and extend battery life.
- Usage Preferences: Determine your specific usage preferences and needs. If you frequently cook in the RV and require additional freezer space, consider a fridge with a larger freezer compartment. Alternatively, if you prioritize a smaller footprint or have limited power resources, a compact or energy-efficient fridge might be more suitable.
Why Would You Want A Solar Package on Your RV?
If you can simply run your fridge off propane or use a generator, why would you bother with the expense of a solar setup? When it comes to RV travel, embracing solar power can be a game-changer and it certainly has been in our case!
Let’s dive into the reasons why solar power is a must-have for your off-grid adventures.
- Renewable Energy Source: Harnessing the power of the sun allows you to tap into a clean and renewable energy source. By utilizing solar panels, you can reduce your reliance on fossil fuels (gasoline, diesel, propane) and contribute to a greener planet. Solar energy is abundant, readily available, and completely free once you’ve made the initial investment in your solar system.
- Dry camping and Boondocking for FREE: With solar power, you can venture off the beaten path and experience the freedom of dry camping and boondocking without worrying about electrical hookups or campground fees. Solar panels convert sunlight into electricity, providing you with a self-sufficient power source to run essential appliances and charge your devices while enjoying remote and scenic locations.
READ MORE ABOUT OFF-GRID CAMPING IN OUR COMPLETE GUIDE TO RV BOONDOCKING
- Large RV Refrigerator While Off-Grid: One common challenge of off-grid RV living is maintaining a reliable power supply for a large refrigerator. Solar power eliminates this concern. With an appropriately sized solar system and battery bank, you can power energy-hungry appliances like refrigerators without compromising on space or functionality. Enjoy residential-size fridges, fresh food, and chilled drinks on your off-grid adventures without the limitations of traditional power sources. We love that our large fridge allows us to stock on groceries before heading out on more remote adventures.
- Power Even During a Power Outage: Solar power provides a reliable backup option during unforeseen power outages. While others may be left in the dark, your RV can remain operational with a well-designed solar system. Whether you’re camping in remote areas or facing disruptions in traditional electrical supply, having solar power ensures uninterrupted comfort and peace of mind.
The decision to equip your RV with solar power goes beyond being environmentally friendly. It unlocks a world of freedom, sustainability, and independence.
Fulfilling Travel Tips
Diving into the world of off-grid RVing and boodocking can be exciting, overwhelming, daunting and confusing… often all at the same time!
To help you navigate the watts, amps, and volts of it all, here are a few of our other guides to help you prepare for the adventure and freedom of dry camping and RVing to beautiful destinations:
- Can you run an RV AC on solar power?
- RV Boondocking For Beginners: How To Live Well in Wild Places
- 51 Best Boondocking Tips
- What Does An Inverter Do? A Complete RV Power Guide
- RV Tips 101: Education Guide For Beginners
- Ultimate RV Maintenance Checklist
- Best RV Travel App For Planning, GPS, and Camping
- Starlink Roam For Remote RV Internet
And here are some stunning places to camp for free while you bask in the bliss of your fridge running on solar while camping off-grid:
- Beautiful Free Camping in Telluride At Last Dollar Road
- Nomad View Dispersed Camping Near Badlands National Park
- RV Camping on The Beach At Lake Powell
- Best BLM & Free Camping in the U.S.