We received our first light bill since we had to start running the AC. The husband and I had different thoughts about the amount of the bill, with one of us believing the bill was reasonable for the size house we have and one thinking it was totally ridiculous. So, that got me thinking... what does your light bill normally cost in the summer? Our bill for mid-April to mid-May is $109. In the heat of the summer, it is about $20 more. I don't have AC in my car and he doesn't have it in his truck, so the AC in the house feels fantastic! We keep it set around 76-78 unless it gets really stuffy.