On the other hand there are two drawbacks. One of them is that it makes some noise, if the van was smaller and we slept right next to it we probably already sold it, but since we are in opposite places at night, that’s okay.
Another problem is that although it does not waste gas, it spends electricity, which means that you will need a second battery and a solar panel.
What we have noticed is that it is also difficult not to have a relay that allows the second battery to charge with the movement of the car, so that we have enough energy.
We were already going to install it, but in any case in the two weeks we traveled without the relay, we had a few days of clouds and the battery with the refrigerator turned on, lights, PC charging, mobile phones … tried hard to give reason to consumption what we were doing.
Note: In winter we are not having this type of energy problem, although we do not have the relay, because the refrigerator works much less so we hardly hear it and it spends much less energy. We have had days with rain, and with little sun and even then we managed to be self-sufficient only with the panel if 100W.