Unless you live in zone 10 or higher, I wouldn't risk leaving aloe vera outside in winter. Might tolerate some very light frosts but it sure wont appreciate them!!

You would need a greenhouse that stayed above freezing if you cannot keep them indoors.

How did you end up with so many plants in only seven years ? I suppose you could give some away. The only other alternative I can think of is to combine several in one pot/container.

We live in Germany, in the Winter temperatures can reach minus ten Celsius so I'm guessing the Aloe Vera will have no chance in that?

I don't know how I've got so many really... I don't know anything about plants so I'm not even sure it is a lot of Aloe Vera or not for seven years!

Would a greenhouse be enough? Or do they need heating inside as well?

Aloe vera supposedly survives temps as low as 0 C. BUT any succulent shuld be kept drier as temps fall. If you have a gh, how cold does it get without being heated? I have unheated sunroom that gets to abt. -4 to -6 C or so, if it gets to lower than -20 C outside. So perhaps it would work? I don't grow Aloe vera, but have many different aloes that have to be indoors. I have 2 pots of A. maculata in that cold sunroom; they seem to be alive. They have not been watered for almost 3mo.

I would give away (or sell) most of the pups - but that is just me!

Yes, you're correct, they won't survive outside. They can handle cold (0-5C) if they're dry, and even a little freezing, but not much. This particular Aloe, as Aloes go, is not very fussy about its requirements (some Aloe species are very difficult to grow unless their native environment is duplicated), and it will grow well outside in the late spring to early fall. It doesn't need a greenhouse, per se, just a warm spot in the house that has some sun.

Maybe offer the extra plants to an elementary school?

BTW, Germany has a strong and vibrant history in cactus & succulent growing and clubbing. There are many Germans who made (and continue to make) significant contributions to the knowledge about these wonderful plants.

https://www.deutschekakteengesellschaft.de/

I have about 12 varieties of Aloe plants and all grow outside year-round, but NONE are Aloe vera. I do live in Zone 10 -- Florida -- so that makes a difference. I have a friend who is a big gardener and at his old house, which had a HUGE garden, he planted Aloe veras outside and just cut them for medicinal purposes as needed. By the time he sold it, he probably had about 20 big ones in the back yard. And of course, they grew new pups. But as several people have said, you need a WARM ZONE to do that in. Beyond that, my best suggestion is to give some away to friends and neighbors.