I clearly recommend putting as many solar panels on the roof as possible. 700Wp is a very good starting value. This corresponds to an area of approx. 3.5m2. You can find it on every roof. Installed later, such a system costs about €6500.00. The 200Wp that you often get from the factory are simply not enough. In addition, they are significantly more expensive ex works.
This is why you need a large solar system:
In practice, 700Wp is about 500W at lunchtime and in summer. Spread over the day you can expect a yield of about 3kWh. With a 12V battery this corresponds to 250Ah per day. That's great and you get along very well with it. But of course you don't only travel in summer.
In October, the yield is already significantly lower. Here you only get half as much as in summer: approx. 1.5kWh per day or 125Ah. That is still sufficient. The gas heater consumes about 2A. Of course only for the circulation pump, not for heating. This consumption can be covered very well by the solar system.
From November to February, however, only 20% of the summer output is achieved. So just 25Ah a day. Basically, that's not enough and you can only just stop the self-discharge. You can get by with it for a weekend. Especially if you drive occasionally. But on a skiing holiday you have to be plugged in. But that's justifiable, because ski holidays tend to be short and if you spend the whole winter in Portugal, you get plenty of sun there.
As you can see from this calculation, one should not calculate for summer but for autumn. You won't get far with 200Wp on the roof.
Alternative 1 - The gas generator:
They're not bad at all! But unfortunately also loud. It's best not to turn it on at a campsite in the summer when everyone is outdoors, but there are still many occasions when it can be used. Wherever there is noise anyway. These things aren't particularly loud, but they can be annoying. They are definitely quieter than a petrol lawn mower.
The big advantage is that they are fed by the gas tank and an incredible amount of energy is stored there. The 3kWh that the solar system only generates throughout the day in summer can be generated by a generator in just one hour. However, only lithium batteries can be charged that quickly. A lead-acid battery must be charged slowly over several hours.
Alternative 2 - The fuel cell
These high-tech devices use methanol as an energy carrier and convert it into electricity. Physically, that's an amazing achievement. You can run them 24 hours a day and they produce around 75W continuously. So that's 150Ah in one day and enough to watch a few hours of TV every evening with great lighting. This also makes it easy to get through your skiing holiday. Because the season doesn't matter here. They don't make any noise, but the fans do make a noticeable noise. As long as they are mounted in the mezzanine or in the rear garage, that's fine.
In terms of price, it costs about the same as a large solar system at around €5500. The sun shines for free, but 5 liters of methanol cost €35 and that's enough for almost 3 days. So for a week's vacation you have to bring 10l with you. Unfortunately, you can't buy it everywhere and therefore usually have to order it. This is a disadvantage and not a permanent solution for the summer.
I would clearly recommend a large solar system. It runs passively and you don't have to worry about it. So you can park the vehicle for a month without having to worry about the batteries becoming deeply discharged.
If you have any questions or comments, please feel free to write them below.
What company builds something like this?
I can definitely recommend WCS in Goch. This is a family business that scores with a lot of passion and great quality. Mr. Tönnshof is the senior and has the electrics under control. His son-in-law Florian Vels takes care of the successor in the workshop. His grandson Philip takes care of customer service. Three generations work in one company at WCS. Here you can be pretty sure that you will always get a good and reliable solution. You can also buy Mobilades there, but the main focus is on the electronics. Whether solar, generators or fuel cells.