Be better to buy them , they are getting cheaper and more efficient as time goes on . I did take a class on photovoltaic systems ( required unfortunately ) , they are very simple , but you cant just throw them up willy nilly and expect to get good power out of them all year . There is a thing on the internet called PV Watts , it gives you the best direction for the area in which you live . Most systems in the US are what they call interactive systems , you are using both your solar cells and the power company , you have two meters . For completely off grid , is called a stand alone system , they are the most difficult to get balanced , you need an inverter , batteries , planning for the average number of no sun days in your area , etc .how you set them up is important also , depends on what you are trying to achieve . Series or/ and parallel makes a difference as well , in what you can get out of them .Some power companies here in the Southwest , where the sun is a curse , rather than a blessing , use solar to heat water for steam turbines .