Hi @LarryC, Supply charges are a part of the overall price of energy, and like usage charges they do vary over time. Supply charges cover the ongoing cost to constantly maintain the network (wires, towers, pipes and so on), passed on to us by your local energy distribution company, so they're not tied to any particular work that you see or don't see done around your home. It's always a good idea to take into account both the supply cost and usage cost as part of the big picture of your energy plan, to make sure you're getting the best deal for you.
There's more info available on our How Energy is Priced page.