It’s modern colonialism to some extent, the USA does/did similar, you ingratiate the people to you so you can exploit the resources OR geography OR populace somehow.

It’s not always evil. It’s rarely ever altruistic.

One way this is done is “we’ll build the bridge to get to the other side of this thing if we’re granted mineral rights for the next LONG TIME” and upfront you get the bridge but the backside is you lost the resource. For the people who were never going to reap the reward of resource … but now they have a bridge … win/win?

This is a downside to these sorts of things. Again, not always evil though.

Teach a man to fish, and you feed him for a lifetime.

Convince a man to let you build a fishing pier with exclusive fishing rights in his pond in exchange for giving him a fish every week, and you've got a customer for life.

In reality, China doesn't need to be so crass as to demand exclusive rights. The mere fact that these are Chinese panels with Chinese hardware means Cuba is going to be dependent on China for as long as they aren't willing to throw out a massive chunk of their infrastructure. As long as this move comes with some change to the material situation that makes Cuba pay China back and then some, China gets richer from it.

Capitalist corporations and nations have done the same for centuries. European colonial empires kept advanced manufacturing in Europe so the colonies couldn't become independent without a massive reduction in industrial capacity. Because of this many former colonies are still economically dependent on Europe and/or the US. China is simply coming in and offering them a better deal.

African economy is underdeveloped. Billions invested to day means trillions down the road with people buying pointless shit like Americans do.