To get the size of the array you need, you'll want to take the equivalent full sun hours figures, and run an average for a year (or for the period of the year you want the solar array to supplement things).  For people using solar energy in rural environments, or trying to live more 'off the grid', investing in a diesel or propane generator to help cover on peak load usage is also worth doing; for more urban residential users, electricity from the utility company is going to be cheaper than a generator.

The other half of the equation is figuring out what you're going to be using electricity for.  Your utility company can provide you with your last year's worth of electrical bills, and you can look over your appliances for more information.  (You will need to note your AC and DC usages separately.  We'll get into AC and DC a bit later).

Start by finding the number of hours each device will be on in a given day; each appliance will also list how many Watts it uses; this will be in the manual or on a tag in the rear of the device.  Devices that run off of batteries will usually have an AC to DC converter unit as part of their set up – a cell phone charger is a good example.

Now, compare the conversion efficiency of the solar arrays of your choice (typically expressed in "watts per sun hour" per panel), multiplied by the number of panels, and see how that compares to the total Watts needed to run your devices.

The output of your solar array is dependent on light intensity and the amount of exposure to the sun, not on how hot it is. On a cold, bright winter day your panels perform just as well as in summer.