What is the biggest disadvantage of solar electricity, or at least, why is it not used much more than it currently is?

How expensive it is is the answer

"The Solar electricity source of energy comes from the sun’s rays. It is more often in the form of a panel known as the solar panel. It has a photovoltaic system that generates and supplies energy in commercial and residential areas. Even though numerous countries are using this type of electricity to save electric-induced power, it is not used for a number of reasons. One is that 1 panel with a size of 6 by 10 solar cells is expensive. There are countries who cannot afford to buy them. Two, it requires a larger area to place the panel. Three, the efficiency is low. The smaller the panel is, the lower its efficiency and therefore produces lesser power to generate a specific area."