The first thing you need to ask yourself is if you want your home to be “on the grid" or “off the grid." This means whether you be tied to the main energy grid that runs within your area or not. In most cases, you want to be on the grid so that if you do run into too many cloudy days you won't be without electricity. The cost to totally setup an “off the grid" system can be much higher, so for the purpose of this comparison I will be comparing solar panels that are tied to the national energy grid.
Solar power is the preferred way of producing your own energy; however, it is usually combined with wind turbines where possible. Solar is primarily best used in the summers where there are a lot of bright sunny days. The major problem with solar is if it's cloudy, although you can still produce energy, the amount of energy generated will be nowhere close to the amount you would produce on a bright sunny day.
We’ll assume that on an average day solar panels generate their maximum power for a 5 hour time span. A typical home's energy use per day is approximately 600 watts, including powering things like your refrigerator, lights, computer, TV, stereo, and other average household items. Over 24 hours, you would need 600 watts * 24 hours within a day= 14,400 watt hours per day.
We know that a solar panel can generate 70 milliwatts per square inch. Multilply this by the 5 hours of gathering maximum rays from the sun = 350 milliwatt hours per day. Based on these calculations you will need 41,000 square inches of solar panels for your house. Which means your solar panel would need to measure about 285 square feet.
Example: What size system is needed to produce 20kwh/day?
20kwh/5h = 4kilowatts
4kw x 1.43 (This is to account for energy loss due to friction heat etc)= 5.7kw
5.7kw system would be required to produce 20kwh/day assuming 5 peak sun hours
Now the average household as you saw above is only using about 15 KWh/day. By installing 20 kwh/day system it will help prevent you from not producing enough electricity.