I'm planning on to install a tankless water heater electric. I'm willing to pay for the tank at a quoted price, but what concerns me is the installation cost of such a unit..pumbing and electrical. My main has a 100 amp panel. There are 15,20, and 30 amp circuits. I have 1 for a 220 line. Does anyone know what it would cost to upgrade that panel to a 200 amp? This was the amount that i was informed to need for such an installation. Thanks