You can choose one of two methods, passive or active. Using passive solar energy can be done by designing your home or any other building with "passive solar design" in mind. Meaning that the southern walls should have windows... the interior where those windows face should have a heat absorbing tile. So that in the absence of sunlight they give off heat. You can also install a solar water heater. This will use the heat from the sun to warm your water.... while some places this is enough it may not be hot enough in the colder or windy climates. Therefore an instant hot water system coupled with a solar water heater will help this and reduce your energy cost.
Or you can use the active part of solar with solar panel systems. These can be large or small panels or shingles for those that want to have a new roof.
Commercially, solar towers are used. An array of mirrors is set to focus on to the pinnacle of a tower and boil water. This steam is used in a similar fashion as a coal or nuclear plant only without the harmful by products. This is another form of passive solar energy in use. For more examples take a look at http://websolarsearch.com/Home+Solar+Power