Some folks would really like to get off the grid: that is, away from monthly bills and municipal regulations. They would like to do as they wish without worry that something they do will offend someone, or needing to pay some corporation for something they must have.
In other words, they want to be free.
What would it take for a person to shake free of the electric utility? So far as pertains to doing so via solar panels, I have found the following.
The two major forms of solar voltaic cells are mono and poly crystalline. They are normally six by six (six inches square). The mono crystalline are sightly more efficient, but both deliver about four watts (4W) in the form of eight (8) amperes at one half (0.5) volt. The cells are combined in series and then pass through some form of protective electronic regulation to charge a battery. If you will continue to use conventional appliance and lighting, then you would also use an inverter to convert the battery power to 120 volts RMS alternating current.
So, how many solar cells would be required to power a house?
Given an average home, the electrical service would be 120VAC at a maximum of 100 amperes, or 12KW (12,000 watts). To get 12KW from solar cells, you would need 12,000W / 4 watts per cell or 3,000 cells. If each cell is the normal 6″ x 6″ form factor, then roughly four cells fit in one square foot surface area, such as a roof or outside wall. So you would need 3,000 / 4 or 750 square feet. This would be an area about 21.5 feet by 35 feet or maybe 25 by 30.
So a typical residential roof could hold enough solar cells to power a typical residential building and have power left over most days because we almost never are using more than 30-40 amperes unless cooking on an electric stove, running an electric furnace, or something like that. This is good because the cells probably will not be operating all the time at peak output either.
The final question is how much would solar cells cost to do this? With Germany having been doing so much solar construction lately there seems to be an availability of surplus cells. There are people who are totally out of touch, as with anything, but prices on eBay, Amazon, and around the net show people seem to be paying between $1 and $2 for a perfect solar cell, with an average around $1.30. Poly is slightly cheaper than mono. Sometimes I saw “free shipping” and sometimes a rather salty shipping fee. You do want to be sure the cells arrive unbroken, because they are quite brittle and break very easily. So to buy 3,000 cells would cost somewhere from $3,000 to $4,000 probably around $3,900. You would then also need tabbing wire and some kind of glass and frames to hold them.
So you could probably do your house in cells for under $4,000. Batteries and electronics would come next.