using solar panels for electricity

If my average daily electricity use is 24 kWh, what size of solar panels that I have to install?
It depends on where you live and if it will be connected to the mains. Some areas receive more solar insolation (sunlight) than the other or even brand solar panels can make a big difference. If you are in a relatively sunny, like AZ or SoCal then probably only have a 3 to 4 kW cover most of their electricity consumption. NREL has a great calculator called PVWatts that can help you determine how large the system needs to be. Find your city home on a map and then enter the size of system you're considering and tell you how much energy they produce in an average year. If you are outside the network, you have to pay more attention to production during the winter months and have a battery bank to cover the evening and on cloudy days.
How Dye Solar Panels Make Electricity from the Sun