While it may seem that your solar panels are always affixed to your roof permanently, the best ones permit repositioning of the angles. Fixed angle panels are just not that efficient.
One of the major benefits of solar energy is that it is renewable. The sun (generally) shines each and every day, and there is no reason to worry that drawing power from the sun will somehow render it unusable in the future. Using solar energy, therefore, is a safe and reliable way to power the Earth.