How Many Solar Panels Do I Need For My RV?

By Kami Turky

Last Updated:

Do you have an RV? Are you thinking of taking it on the road this summer?

If so, you need to think about solar power!

Investing in a solar system for your RV won’t just help you save money and reduce your carbon footprint, it will also allow you to boondock in locations that might otherwise be inaccessible.

So, how many solar panels do you need for your RV?

The average RV requires 4-7 200W solar panels to stay powered up while on the road.

Of course, this depends on a number of factors.

And in this step by step guide, I’ll show you exactly how to calculate how much solar power you need for your RV.

So, let’s dive in!

Key Takeaways

  • The average RV consumes 5-20kWh per day.
  • To design a solar system you must first know the amount of sun irradiation your panels will receive also known as peak sun hours.
  • You should expect 4-6 peak sun hours per day.
  • The average RV will need a 1kW solar system to cover its energy needs.
  • You must factor in power losses that happen due to heat, shading, inverter efficiency, etc. These losses could make up 10-30% of the total power generated.
  • With power loss in mind, the average RV solar system should be about 1.2kW to cover its energy needs.
  • You need a bigger battery to store all the energy generated by your solar panels during the day.
  • The average RV needs a 24V 300Ah lead acid battery (50% DoD) or a 24V 200Ah lithium battery (80% DoD).
  • The average RV requires a 50A charge controller to regulate the battery charge and prevent overcharging.
  • The average RV needs a 2500W inverter.

How to Design a Solar System for Your RV [Step by Step]

1. Calculate Your Energy Consumption

Every RV is different, so the first step in designing a solar energy system for your vehicle is to calculate your power needs.

This is the most important step, as it will inform how large your solar system needs to be in order to power all of your devices and appliances.

So how do you go about calculating your power needs?

There are 2 ways to do this:

The first and easiest way is to use a power meter.

A power or energy meter is a device that keeps track of how much electricity your RV uses.

Just connect a small power meter to your RV’s electrical system and monitor its reading over the course of several days or weeks.

This will give you an accurate estimate of how much power your RV uses per day.

The second way is to list out all of the devices and appliances that you plan on using in your RV and determine how much power they consume using this formula:

Appliance Daily Energy Usage (Wh) = Appliance Power Rating (W) x Number of Hours Used Per Day (h)

Go through each of the devices you plan on using in your RV and make a table that lists the appliance, power rating, and the number of hours used per day.

Once you have your list, add up all of the numbers to get a total daily energy usage.

Note: Appliances with compressors, such as refrigerators, freezers, and air conditioners, don’t run 24/7.

They have something called duty cycles, which means they work for a certain amount of time and then rest.

For example, many refrigerators have a duty cycle of 35% – which means that they only run for 21 minutes out of every hour!

If this is the case, you will need to factor duty cycles into your calculations by multiplying the appliance’s power rating by the appliance’s duty cycle percentage.

So if this fridge is 40W, then its energy consumption per day is 336Wh (40 x 0.35 x 24), not 960Wh.

For our example, let’s say that your RV uses 5kWh (5,000W) per day.

2. Find out How Many Peak Sun Hours You Get per Day

Solar panels work by converting sunlight into electricity.

So the more sunlight your solar panel receives, the more electricity you’ll produce from the solar system, and the smaller the solar array needed to power your RV.

Sadly, sunlight isn’t equally distributed across every part of the world.

Some places, like the Southwest US and areas in Australia, receive much more sunlight than other parts of the world, so you’ll need to take this into consideration when designing your solar system.

We calculate the amount of sun irradiation using something called peak sun hours.

Peak sun hours refer to the number of hours per day that the sunlight intensity averages 1000W/m².

There isn’t much to do here, except to navigate over to a peak sun hour calculator and enter your location (state, city, or zip code).

This calculator will then go through weather data from your location and determine the average number of hours per day that you get peak sun.

For our example, let’s assume we are boondocking in California and we get an average of 5.31 peak sun hours per day.

3. Calculate the Theoretical Solar System Size

Now that you have a good idea of your daily power consumption and how much sunlight you get per day, you can use some simple math to determine how large of a solar array you will need in order to power all of your devices.

Theoretical Solar System Size (W) = Daily Energy Consumption (Wh) / The Number of Daily Peak Sun Hours (h)

Since our daily energy usage is 5,000Wh and our peak sun hours are 5.31h, the theoretical solar system size we need is 941.6W or 0.95kW.

4. Factor in Your System Power Losses

A solar array is an electrical system, and as is the case with any electrical system, there will be some power losses.

These losses come from a number of different places.

For example, if it’s too hot outside, the resistance in your solar panels will increase, resulting in a loss of power as some of the electricity is turned into heat.

Another common source of losses is shade and dust.

If a part of your solar panel is covered in dust or is shaded by a tree branch, it won’t be able to produce as much electricity.

The mismatch between the voltage of your solar system (~18V) and your batteries (~12V) will also result in energy losses.

Finally, inverters can also incur some power losses.

The best inverters on the market have conversion rates of ~98%, meaning that you’ll lose 2% of all of the electricity you generate, this may not seem like much, but these numbers will add up quickly.

In fact, a residential solar system might have a 23% or greater power loss!

So, how do you account for these power losses?

I’d add about 15% to your theoretical solar system size.

Real Solar System Size (W) = Theoretical Solar System Size (W) x [1 + System Losses]

So for our example, our real solar system size should be about 1082W or 1.1kW (941.6 x [1+0.15])

5. Calculate How Many Solar Panels for Your RV

Solar panels are rated in watts (W).

This rating tells you how much power your panel will generate for every hour of 1,000W/m² sun irradiation it receives (every peak sun hour).

So if you have 2 panels one that is rated at 100W and another that is rated at 300W, the 100W panel will produce 100Wh, while the 300W will produce 300Wh of electricity for every peak sun hour they receive.

To calculate how many solar panels you need, simply divide your real solar system size by the power per panel.

How Many Solar Panels (n) = Real Solar System Size (W) / Solar Panel Wattage Rating (W)

Let’s assume we’ll use 200W solar panels.

Therefore, our 1.1kW RV systems will require about 5-6 200W solar panels to power all of our devices.

6. Calculate the Solar Battery Size

Ok, so you’ve determined how many solar panels you need, but what about your RV’s battery?

The system will produce all of this electricity during the day, so you need a large battery to store all of that power for use at night.

The average RV battery is about 80Ah, which is really not enough for a system that big.

So, what size RV battery do you need?

Here’s how to calculate it:

Battery Capacity (Ah) = Daily Energy Consumption (Wh) / Battery’s Nominal Voltage (V)

For our example, our battery voltage is 24V, so our battery size should be 5,000Wh / 24V = 208Ah.

Now, there is an extremely important factor that you need to think about: your battery’s Depth of Discharge (DoD), which is the amount of electric charge that you can safely withdraw from your battery without damaging it.

Typically lead acid batteries have a DoD of 50%, while lithium batteries have a DoD of 75-80%.

In other words, a 100Ah lead acid battery can only store 50Ah, while a 100Ah lithium battery can only store ~80Ah.

Real Solar Battery Size (Ah) = Amount of Charge You Wish to Store (Ah) / Battery DoD

Since we plan on using a lithium battery with a 75% DoD, our solar battery size should be about 208Ah / 0.75 = 277Ah.

7. Calculate Charge Controller Size

We don’t want to overcharge our battery, otherwise, we’ll damage it.

That’s why we need a charge controller to monitor the voltage levels of our system and to only allow a specific amount of energy to flow into our battery.

You can easily calculate the charge controller needed using this calculator.

8. Calculate the Inverter Size

Inverters are used to convert the DC electricity generated by our solar panels into AC electricity that can power all of our RV devices (fridge, TV, etc).

The size of the inverter you need is determined by the continuous power rating, which is the maximum amount of power that the inverter can produce consistently.

You want your inverter to be able to power all of your devices at the same time (max load), so if you have a 40W fridge, 60W laptop, 20W LEDs, and a 200W TV running at the same, you’ll need an inverter rated at no less than 320W in order to power all of these devices at once.

You also need to factor in the inverter conversion efficiency.

As mentioned in the power losses section, inverters don’t convert energy perfectly, so you need to account for that power loss when calculating the inverter size needed.

Inverters are typically around 85-90% efficient, so you need to keep that in mind.

Inverter Size (W) = All Appliances Running at the Same Time (W) / Inverter Efficiency

So, assuming our RV requires 400W at the same time and our inverter is 90% efficient, then our inverter size should be 400W / 0.9 = 444W.

RV System Design (Worked Example)

Let’s say we want to design a system for this RV:

  • Energy Consumption: 7kWh/day (7,000Wh)
  • Location: Arizona (5.62 peak sun hours/day)
  • Power Loss: ~10%
  • Solar Panel Wattage: 320W
  • Battery Voltage: 48V
  • Battery Type: Lead Acid (50% DoD)
  • Max Load: 500W
  • Inverter Efficiency: 80%

Ok, the first thing we would do is figure out our system’s theoretical size.

Theoretical Solar System Size (W) = Daily Energy Consumption (Wh) / The Number of Daily Peak Sun Hours (h)

This means that we need a 1,245W or 1.25kW solar system (7,000/5.62).

Next, we need to factor in the power losses, which are 10% of the energy produced in this example.

Real Solar System Size (W) = Theoretical Solar System Size (W) x 1.10

So, our real solar system size is 1,369W or 1.37kW (1,245 x 1.10).

Now that we have the system size, let’s calculate how many solar panels we need for our RV.

How Many Solar Panels (n) = Real Solar System Size (W) / Solar Panel Wattage Rating (W)

With a 1,369W solar system and 320W solar panels, we would need 4-5 solar panels (1,369/320).

Next, we would calculate our battery size.

Battery Capacity (Ah) = Daily Energy Consumption (Wh) / Battery’s Nominal Voltage (V)

From this, we can conclude that our battery needs to have a capacity of 145.8Ah (7,000/48).

And since we have a 50% DoD lead acid battery, then we need a 290Ah battery.

For our charge controller, we used our calculator and it appears that we need a 33.3A charge controller, so we’ll get a 50A one just to be safe.

Charge Controller Size

Finally, the inverter.

Inverter Size (W) = All Appliances Running at the Same Time (W) / Inverter Efficiency

Since our max load is 500W and the inverter efficiency is only 80%, then we need a 625W inverter (500/0.80).

FAQs

Will a 100 Watt Solar Panel Keep My RV Battery Charged?

A 100 watt solar panel will provide about 33Ah and since most RV batteries are 80Ah, then you’ll need 3 100W solar panels to keep your RV battery charged.

Is It Better to Run Solar Panels in Series or Parallel for RV?

It’s better to run solar panels in parallel for RV, especially if your solar panels don’t have a bypass diode to minimize shading losses.

However, whether to run solar panels in series or parallel also depends on your solar system’s voltage, which is determined by the battery bank voltage and inverter/charge controller ratings.

How Many Batteries Do You Need for a System in RV?

A system for RV will require 3 100Ah lead acid batteries or 2 100Ah lithium batteries.

Can an RV Run Completely on Solar?

Yes, an RV can run completely on solar if it has the right size system and battery capacity.

Is It Worth Getting Solar on an RV?

Getting solar for your RV isn’t only a cost-effective way to power your appliances, but it also allows you to boondock or camp off the grid for longer.

Plus, it’s great for the environment!

So, yes, solar is definitely worth getting for your RV!

Does Solar Charge RV Battery?

Yes, a system will charge your RV battery. However, it’s important to ensure that your system is sized correctly and matched with the correct battery type for optimal charging.

How Much Does It Cost to Hook up Solar to an RV?

Simple RV solar systems can cost you anywhere between $600 and $5,000, depending on the size of the system.

Conclusion

As promised, we’ve covered everything you need to know about how much solar power do I need for my RV.

We showed you how to calculate the best system size for your needs and what size battery, charge controller, and inverter you need to get off-grid.

We hope that you found this article helpful and if you have any additional questions, feel free to let us know in the comments below!

Kami Turky

Kami is a solar engineer with nearly a decade of experience in researching, testing, and reviewing various solar products.He has also provided technical consultation to several organizations on the best ways to incorporate solar energy into their operations.When he’s not busy helping others find the best solar solutions, Kami enjoys spending time outdoors, hiking, camping, and exploring the natural wonders of his home state.

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2 thoughts on “How Many Solar Panels Do I Need For My RV?”

  1. Sir, please help me. I bought a 12v battery from Walmart ,hoping to use , with another one to power a smaller apartment size frig using a solar panel to keep it charged. This was before I read anything on your website (I’ve also subscribed to your newsletter , by the way) about sizing all this shigiti, an am wondering if I should take it back and go for the lithium one sized by your MIT calculations. It says Group Size 24MS, 625 MCA if that makes any sense to you. Sir, if you decide to answer, please don’t mention how stupid I am. My ego is already fragile enough.

    Reply

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