Solar Panels

How Many Solar Panels Do I Need For My RV?

By:Michael Johns

Solar panels for RV

Solar panels are one of the best additions you can make to an RV or camper.

It gives you the ability to charge your batteries without access to mains power or even running your engine.

If you like to spend time parked up off-grid to kick back and relax, then solar is the way to go.

It means you won’t even have to go for a drive just to charge your batteries!

I loved the solar panels on my camper as it gave me complete freedom to disappear during the summer months.

Unfortunately, it can be tricky to find the right setup for your vehicles. If you browse product ranges you’ll see individual 30 watt panels, 1200 watt complete kits, and everything in between.

So how many solar panels do you really need on an RV? Well, let’s take a look at the factors to consider and a good size for your needs.

How Many Solar Panels Do I Need To Power My RV?

To understand how much solar power you need there’s two main points to consider.

  • Daily power consumption
  • Battery storage capacity

Knowing the requirements of these two factors will make it much easier to size your system correctly.

1. Daily Power Consumption

This is simply the amount of electricity you will use every day. It is the total amount of energy your appliances will use in a 24 hours period. Ideally, you will have enough solar power to produce this amount of electricity every day.

The electronics you run in your vehicle will directly affect your energy usage (duh…)

For example, if you just want to run LED lighting, charge phones, and laptops, then you won’t need a very big solar panel at all. A 100 watt panel will keep you going.

On the other hand, if you plan to run kitchen appliances like a refrigerator or microwave then you’ll require something more extensive. 

With a total number of daily watt-hours (Wh) you will easily be able to compare this to solar panel output. 

For example, you could expect a 100 watt solar panel to provide 400Wh of electricity during a sunny day. That means if you will use 800Wh per day you’ll need at least two 100 watt solar panels.

2. Solar Battery Size for RV

The second thing you need to consider is the storage capacity of your batteries. Remember, solar panels only work at their optimum during peak sunshine hours. The power output will reduce significantly during the morning and evening. Plus it will be zero at night. 

You will need to store energy in your batteries to use your system effectively. This means your solar panels must be sufficient to match your batteries.

If your solar panels are too big, you will generate more energy than you can store in a battery. This is a waste as you will spend more money than you need to on your solar panels.

Contrastingly, if your solar panels are too small you won’t be able to charge your batteries enough to keep you powered up!

Using the knowledge that a 100 watts of solar power generates 400Wh per day you can work out if you will have enough to fully charge your batteries. 

Storage capacity is usually marked on a deep-cycle battery in Ah (amp-hours) and Wh (watt-hours). As you can see here:

100Ah and 1200Wh battery for RV
100Ah and 1200Wh battery

To be honest, there is no right or wrong answer when it comes to sizing your solar panel system on an RV. 

It all comes down to your energy usage. 

An installation like 500 watts of solar panels and 300Ah battery capacity will work for the average camper.

Are RV Solar Panels Worth It?

I have never spoken to anyone who has regretted installing solar panels on an RV. 

That tells me one thing: They are definitely worth it!

After you get past the initial installation and cost, it is a free way to produce electricity anywhere you end up. All you need to do is park in the sun.

Adding to this, they are a set-and-forget solution. You don’t need to remember to plug in or switch on. Everything runs automatically. Even maintenance is a breeze, you just need to clean the panels if there’s dust or dirt building up.

The cost isn’t too bad either, especially if you already have batteries and a power inverter installed. You can pick up a 200 watt starter kit for less than $300 and add more capacity as you go.

How Many Watt-Hours (Wh) Does an RV Use?

In my experience, the average camper or RV uses between 2 – 4kWh a day. That’s 2000 – 4000Wh.

There’s a lot of different figures blasted around the internet. But the best way for you to find out is to conduct your own tests. You can simply use your RV normally for a day and see how much battery energy you get through. 

Once you have your total watt-hour usage you can divide this number by 4 to get your required solar panel wattage. For example, 2000Wh ÷ 4 = 500 watts.

How Many Amps-Hours (Ah) for an RV?

Another way to work out your energy usage is in amp-hours (Ah). This is a unit of total electrical current consumed in an hour.

It is useful to know as battery storage capacity is often rated in Ah. For example, you can get battery sizes of 50Ah, 100Ah, 200Ah, and so on.

In direct sunlight, you can expect a 100 watt solar panel to generate 5Ah. Or 30Ah in a day. That means you are able to charge a battery with 30Ah in a day with 100 watts.

So if you have 500 watts solar power that’s 150Ah of electricity produced a day to charge your batteries.

I would estimate the average RV uses 150Ah- 350Ah per day.

How Long Will You Be Off Grid?

You should factor in how long you will be spending off-grid and in a stationary position. If you are spending 1 day away from a mains hook up you won’t need such a big solar panel system. This is because you can hook up at a campsite.

On the other hand, if you want to spend multiple days off-grid without moving you’ll need something more substantial. Plus you should consider how much driving you’ll be doing as a split-charge relay will also charge you batteries from your vehicle engine.

I can’t answer these directly as it will be down to your habits. But you can use the energy usage factors above to help work this out.

RV going off-grid

Is MPPT Controller Worth It?

One other thing to increase your RV solar panel efficiency is the type of solar charge controller you use. This is the device that sits between your solar panels and batteries to manage the charging.

It serves two main purposes. The first is safe battery charging to ensure you don’t overcharge your batteries. (That would be very dangerous).

The second is to manage the charging efficiency. MPPT charge controllers can increase charging efficiency by up to 30% compared to PWM controllers.

So if you want to get the most out of your system then a more expensive MPPT controller is worth the investment.

Final Words on Solar Panels Size for RVs 

The amount of solar panels you need for your RV depends on how much energy you use each day.

If you’re spending extended time off-grid you’ll need enough electricity production to meet your consumption and keep your batteries charged.

You can do the maths to work out your energy usage. Or for a real number, you should run a test in your RV. Monitor how much battery capacity you generally use during a day. In addition, you should ask owners of similar sized vehicles for their advice.

Armed with the correct information you will be able to correctly size your solar array. I would suggest starting smaller and working your way up if you need more power.

It’s quite easy to hook up more solar panels as you go to avoid overspending.

For a rough guide, you could look at 500 watts of solar panels coupled with a 300Ah battery capacity to get you started. Plus read my guide to the Best Solar Panels for RVs.