Way back when, in the early days of solar energy technology, more than a few people in the scientific community were eager to point out that most of the energy we use is solar, either directly or, in most cases, indirectly.
Direct solar energy is the use of solar panels to do things like heat water or photovoltaic cells to generate electricity. Indirect solar energy is what is derived from burning wood, petroleum and coal, as well as wind energy. Wood is grown thanks to energy from the sun; fossil fuels fall into the same category, except the energy they captured is much older. Wind energy results from the weather, which is driven by the sun.
Strictly speaking, only nuclear energy and geothermal power aren't solar.
Direct solar energy, the kind derived directly from the sun from various kinds of energy capturing devices, is regarded as the most desirable from an ecological standpoint. So long as the sun shines, it should be able to provide plenty of power that can be stored to light bulbs at night, heat houses when it's cold and even cool them when it's hot, all without generating pollution or depleting finite resources.
Unfortunately, advocates for direct solar power historically have relied heavily on the altruistic advantages of the energy rather than focusing on making it more practical or affordable. The issue with energy, after all, is and always will be that the cheapest form will generally win out.
A case in point is the latest Harford Community College effort to take advantage of solar power not because it's the altruistic thing to do, but because it has the potential to save the school some money. A power company, Tecta Solar, is poised to reach an agreement with the college under which solar-electric panels will be put on the roofs of school buildings and the power generated sold to electric power companies. The college, for providing the space, will get a discount on electric bills down the line.
The altruistic value of the endeavor is a fringe benefit, though, it could be argued, an important fringe benefit.
All the same, it is worth pointing out that solar power, wind power and geothermal power are all available in one form or another in most places on earth. Getting them to replace fossil fuels will depend on some bright person or people putting together competitive, dependable technology packages and competing directly in the energy market, not trying to instill feelings of guilt to get people to do the ecologically friendly thing.