The right solar system for your RV

Solar energy in the RV means more freedom and independence. And this is exactly what traveling with a RV is all about. Especially the wild, lonely and natural places, which invite you to rest, have no power supply – especially here the supply with solar energy is the best choice. Here we explain why, what costs arise and which components are required.

In addition to your own home, there are other useful areas of application for photovoltaics. For example, it is becoming increasingly popular to generate electricity yourself when travelling, using a specially designed solar system for RVs.

Traveling with your own RV is a dream – especially because of the independence. Exactly this aspect of freedom is of course further increased by your own power supply!

A gas balloon is enough for a long time and the water tank is easy to fill up in an emergency, you can simply bury the organic waste. But how and where does electricity come from? An accumulator operated with the help of the motor-generator is unprofitable and overloads the resources of the motor. Carrying a gas generator with you is also bad: It is noisy, stinks, requires refueling and is a fire hazard. The ideal variant is to charge your RV batteries with solar energy on the go. And that works with the help of photovoltaic systems for your RV. Regular electricity – ecological, clean, environmentally friendly and silent!

1. How expensive is a solar system for my RV?

A solar system for a RV or caravan is available for less than $500. The final price will of course depend on various factors.

On the one hand, what performance the photovoltaic system should bring.

Anything between 50 watts and several hundred watts is available.

Which additional components are required.

How will the solar system be installed – and above all, by whom.

Motorhome owners can sometimes do without an solar inverter and the solar battery, provided that the appropriate parts are already installed and the capacity of the existing battery is sufficient. If you want to expand your camper yourself or equip your caravan with a solar system, you definitely cannot avoid these products.

There are specialized providers who offer solar system sets including installation. Of course this has its price. Then again, you can find complete sets for camping solar systems on the Internet, which you can actually easily assemble yourself according to the instructions. If anything is unclear, one of the salespeople will be happy to help over the phone.

In order for this to be guaranteed, one should pay attention to the competence and quality of the seller when buying. If his solar systems are sold from Hong Kong, not only will it be difficult with the right of withdrawal and complaints, but competent support with the installation could also be difficult in case of doubt.

1.1. Where can I buy a solar system for my caravan?

An uncomplicated way is to buy a ready-made solar set. Solar panel, MPPT solar charge controllers and batteries are perfectly matched here and the necessary parts for attachment and assembly are also available. Here are some examples of such solar sets – you can find more in our shop (click here).

As with a “large” solar system, it is not just the price that counts, but also the quality and, if desired, the installation or service.

Just as we compare electricity prices online to find a cheap electricity provider and should also pay attention to ratings and opinions from previous customers, this also applies to the purchase of solar systems.

Even if the investment is significantly lower than for a large photovoltaic system for your own home: if you buy carefully and don’t save at the wrong end, you will be happy with your camping solar system for a long time.

2. What parts does the PV system need for the RV?

In order to install your own power supply on the RV you need:

12V solar panels

12V battery

Possibly solar mounting spoiler

Solar charge controller

Solar cable

The roof duct

Installation glue

Now let’s take a closer look at the individual components.

2.1. Which solar panels should you choose for the motorhome?

The solar module is the heart of the system. This is where the electricity is generated, which charges the batteries in the vehicle. There is:

Monocrystalline solar Solar panel

These Solar panel are ideal! They have the greatest efficiency compared to the area required.

So despite the small area, a large current yield.

Polycrystalline solar Solar panel

Are cheaper, but the area required is usually a little larger compared to the monocrystalline Solar panel.

In addition, they are not as resistant to aging.

CIS solar cells

These are said to charge the battery even in the shade and when the sky is overcast.

It is true that CIS Solar panel perform better in diffuse light or partial shading than a monocrystalline Pv module of the same peak performance.

But if you take the same area as a basis instead of the same peak power, monocrystalline Solar panel have an advantage. They would be a lot lighter and much cheaper to buy.

If you compare both types, you have about 20% more power with the monocrystalline solar module. With diffuse light, this makes up for the difference, with full sun you even have the full 20% more power and that with less weight and lower costs!

In addition to these three types, there is also the distinction:

Flexible solar panels

The right choice for slightly curved surfaces, or if you really want to save every gram of weight.

Flat design, classic glass/aluminium frame design

Otherwise, these Solar panel are the right choice. You can combine Solar panel with the same number of cells.

2.1.1. Should you use 12V or 220V Solar panel

You should use solar Solar panel with 12 volts to supply your RV or caravan and buy suitable equipment. Almost all technical devices are available in 12V versions.

Why 12 volts? Many of our everyday devices actually run on 12 or 24 volts. They have a built-in power supply, which transforms the 220V from the socket to the lower voltage. If you were to use 220 volt devices in the RV now, you would have to install an inverter, which converts the electricity to 220 volt AC voltage. The power pack installed in the connected 220V device then converts the current back to 24 or 12 volts.

However, this results in performance losses that can be avoided if everything is designed for 12 volts.

2.2. How do you attach the Solar panel to the RV?

For this there is the so-called solar spoiler, which is attached to the roof. The spoiler is usually glued or screwed. When gluing, you don’t need unnecessary holes and experience shows that the glue is reliable.

The solar Solar panel are then screwed to the spoiler – and can also be removed if that becomes necessary later.

Aluminum spoilers have the advantage that they do not weather + noble optics.

If you have chosen flexible solar Solar panel are glued directly to the roof.

Solar Solar panel are known to have the best efficiency, i.e. the best electricity yield, when the sun shines on them at an angle of 90 degrees. Since the sun moves throughout the day and also has different angles depending on the season, the solar Solar panel would always have to track the sun. They should be rotatable and tiltable. Ideally, they should also automatically follow the sun. With such a system, twice as much electricity can be generated, but at the same time it is expensive and often not worthwhile for such a small system on the roof.

The most commonly used solution is mounting brackets, which can be used to manually fold up the Solar panel on the roof so that they are better aligned with the sun. Disadvantage: You have to climb onto the roof every time. And the mounts are expensive. Federal solar tax credit may save you a lot of money.

2.3. What do I need to know about solar cables and roof ducts?

Experts advise connecting the Solar panel in series up to approx. 400Wp. Advantages: maximum effectiveness, no additional plugs required, easy connection.

When connected in series, the voltage in the cable increases, not the current. The 1x4mm² solar cable should be sufficient for a cable length of up to 10 meters between the controller and the solar module. However, you will usually find the appropriate instructions on how to proceed in the kit or solar set. Series vs parallel battery is also very important, you must know the rules when installing it, and you can ask an electrician to assist you if necessary.

The roof duct closes the hole for the solar cable on the roof. It is also glued and is weatherproof and (who would have thought it) waterproof! If you follow my connection suggestion, I recommend the double roof duct.

Keep cables as short as possible.

This avoids losses – especially where the highest currents flow (from battery to solar controller, battery to inverter, between solar controller Solar panel, between power-hungry consumers.

The lines can never be too thick, but too thin.

Nevertheless, thick cables are heavier and more expensive.

Therefore: Calculate cable cross-section

Example – cable from solar controller to battery:

The Steca PR3030 charger supplies a maximum of 20A. The cable to the battery is 1.8 m long. You want a maximum loss of 1%.

The formula is then: (30 x 0.0175 x 1.8 x 2) / (0.01 x 12) = 15.75.

So you need a cross-section of 15.75 mm2 – the next possible larger cable cross-section of 16mm would be suitable.

2.4. Which solar controller should you use?

However, the solar cable must not be connected directly to the battery, but is connected to the solar controller. The solar controller ensures that the consumer battery in the RV is optimally charged. It also protects against overcharging when the motorhome is not used for a long time. I strongly recommend MPPT solar controllers – because only with an MPPT charge controller can you use almost 100% of the available solar power. MPPT solar charge controllers bring 20-30% more solar charging current than cheaper PWM (shunt) solar charge controllers.

If possible, the solar trickle charger controller is now connected directly to the RV battery. Although vehicles with Schaudt EBL 99 and similar have a solar input, this reduces the solar yield again thanks to the too thin conductor tracks. With the EBL220 with integrated battery computer, the solar input is sufficiently dimensioned and I haven’t noticed anything disadvantageous so far.

Attention with Votronic MPPT charge controllers: They can only process a maximum of 50V solar voltage – so you can connect a maximum of 2x100Wp in series.

At Victron there are two numbers on the regulator. The first number indicates the maximum solar voltage. When connected in series, they add up the open-circuit voltage of the module and the sum must not exceed this value under any circumstances.

The second number indicates the maximum possible charging current of the controller to the battery. Multiply the battery voltage by the maximum charging current of the controller – get the possible solar power.

The Renogy series includes a Bluetooth module, which enables remote solar display on a smartphone or tablet.

The BlueSolar series is cheaper and does not have this function integrated – but an external Bluetooth dongle can be retrofitted here, then the controllers can do the same as the Renogy series.

3. How to calculate PV system for the RV?

The following 3 components must be correctly matched:

the solar panels

the solar controller

the batteries

Step 1 – consumers determine:

It is therefore important for every consumer:

the required voltage (volts)

the watt consumption

usage time per day

This results in the sum of the daily required power (Wh) and the electrical charge (Ah). The solar calculator is what you must know to calculate the number of solar panels you need based on your electricity needs.

In order to determine the size of the required solar battery, the question is how many days you want to be autonomous or how you can bridge bad weather without sun. If you take e.g. 3 days, then you calculate Ah x 3, i.e. 15.3 * 3 = 45.9 Ah.

Important: Pay attention to the discharge depth of the batteries. A complete so-called deep discharge damages the solar battery. Manufacturers therefore specify a depth of discharge (usually 50% to 90% of the stored amount of electricity).

By the way: Lithium batteries do not have to be charged to 100%, the service life is even better with a charge level of 20-80%. And you can charge them with any charging current (current up to 50% of the capacity) – without any disadvantages on the service life.

Step 2 – Selection of solar panels:

The Solar panel should supply enough power in one day to fully charge the batteries.

With approx. 15.3 Ah per day and three days of self-sufficiency, you get the mentioned 45.9 Ah that the system has to deliver per day to charge the batteries.

The important information for comparing the Solar panel are:

The maximum power Pmax in watts.

The voltage in volts.

The maximum current in amperes.

Step 3 – The Charge Controller:

The charge controller must match the battery. Maximum power and maximum current are important for the charge controller.

Depending on the current supplied by the Solar panel, the controller must be designed for this: e.g. 400 watt solar panel with 5.7 A … 2×5.7 = 11.4 amps and 200 watts module power.

3.1. Is a solar system for a RV even worth it?

That depends on your goals. With small solar systems you can reach a service life extension – but it must possible. but can be fully recharged at a socket every few days. But you can easily plan a solar system for the RV in such a way that you achieve complete self-sufficiency!

4. Small alternative for camping: foldable solar Solar panel

Do you also like to go camping? Best in the middle of nature?

Of course, the many advantages also have a few disadvantages. Cold beer or butter are desirable, but hardly possible without electricity. So that you always have enough electricity available here, you can use a small solar system with a battery – sometimes referred to as a solar case.

These systems are quick to set up, depending on the system, the Solar panel are simply unfolded and can even use the sun to generate energy behind the windshield of your vehicle (so safe from theft).

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