If we build what amount of solar power will we need as a family of 2 adults 3 children?

We are looking at solar power for our property vs electricity, we will have 2 adults 3 children who use the internet, down load music, a dad who taped things on foxtel, the land will be 24 acres and the house 23 squares, we will have a barn that will need running and also farm stuff, any ideas what amount i will need to look at getting?

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