Storing potatoes the wrong way

I thought that by leaving my potatoes in my dark, cool basement would do well with them.  Apparently not.  I'm not entirely sure what the problem is, but these things seem to have grown all winter.  I tend to think that the issue in my basement was that it got too light down there.  There are some windows, but I didn't think that it got too light.  A few of the potatoes also looked a little bit greenish, which is what normally happens to potatoes when they are growing and get exposed to too much sunlight.  Regardless, the potatoes will not go entirely to waste, I can make some sort of potato soup.  This year my potatoes will be in pitch black however I achieve that.