What does "over" mean? Is it connected with "change"?
You're correct in that "over" is connected to "change". Here they have the same meaning as the phrase "change over" which is used when we talk about a complete change from one system or method to another, and that is what is being discussed here. When the two are split like this the words or phrases that come after "changing" refers to the current and the words after "over" refer to the new. This sentence could also be reworded to have change and over next to each other and still convey the same meaning. Ex: Perhaps changing over the whole system to hydrogen. Ex: Most airlines have completed the change from paper tickets over to e-ticketing.