A) i can sell the extra power that i produce back to the electricity company thats about 1000smth euro per year or 100-120 per month and thats a stable profit
This is the best option, resell that extra energy, and get those 100$ you claim to get.
With that money, you buy BITCOIN and get more coins than you can mine.
Regardless of your mining system, you should work with "safety" margins of 100-200w/h to ensure your equipment is always up and running.
Of course, if you are connected to the normal network, there is this margin. But, with your own production system, you have to have that kind of margin, to be able to ensure that it works.
This margin allows you not to overload your network or the equipment, as well as support the "peaks" that the equipment can generate at some point in operation.