Let me assume it was this comment you didn't understand:
Originally Posted by
keepitsimplestupid
I was assuming a 120/240V system. He can also go grid tie, but in that case you don't have power when the electricity fails.
The system would have to be way too big. An AC system has a 40-60 amp fuse. (40*220) is the number of watts the AC system may need to start. An electric furnace might be 15 KW.
Those kinds of loads are best placed on fossel fuel like propane or natural gas. This reduces the electrical requirements. Solar hot water and or solar heat collection systems are more efficeint.
At this point, I'm assuming this isn't a cabin in the wilderness in which you want to live off-grid. You have to make livestyle changes to do that.
The easiest and best method to REDUCE your consumption of electricity is to not use batteries, but rather dump electricity they you are not using back into the powerline thus making your meter run backwards.
With this system, the line must have power from the utility. Once the utilies side is zero, the system MUST disconnect to protect the lineman working on the lines.
You can have both system, grid tie and non grid tie and the charge controller looks at the inputs and figures out what to do.
Inputs can be generator, solar, wind, utility.
Outputs can be batteries and utility.
So it's like the first priority is to keep your batteries charged.
If the batteries are charged then divert excess power (wind/solar) to utility.
2nd priority is to always have power.
Have utility power - use it
Lost utility power - switch to wind, solar excess to batteries
Loose battery power - switch to generator
I don't have all the cases, but you get the idea, I hope.
The nornal solar systems they are installing here are about 8 KW. One person I know has an 18 KW system.
The utility would really like everyone to be using demand metering. It could be based on the largest amout of power you used in a 15 minute interval in a month.