I want to build a a back up system for power outages but then able to expand it later to be the main source of power. I can build my own panels but need to know what is the best efficient solar cells to buy and where? (monocrystalline N type?) I would like to build 2 to 4 425 watt solar panels for a start. Is AGM batteries the way to go or others? How much of a inverter to power the whole house and still be appropriate for starting out as back up? Battery Power control unit? I live near Portland Oregon so if there is a place to buy here for Diy'ers to save on shipping that would be great! My house is 1600sf and plenty of roof facing south. Initially, I want to be able to power the fridge, pellet stove blower, wifi, tv and maybe the washer and dryer (240v) Our heating is gas. Thanks for your advice.