Why does my solar panel not seem to work even though only one small part of it is covered up/in the shade?

A solar panel is actually just a casing that holds multiple small solar cells. These are the blue or dark-blue squares inside the solar panel that are actually absorbing the light and producing the energy. Each individual cell has its own voltage and amperage that are normally both very small. By combining these small cells together, the voltage and amperage can be combined into the larger output which is what the entire solar panel is rated for. Connecting cells in series combines the voltage of each string of cells into one larger output voltage, and combining cell strings in parallel combines the amperage of each string. Cells combined in series are often visible by the metal strip running in a straight line down a few of these squares. When cells are combined in series, the voltage adds up but the amperage does not. Instead, the string takes the lowest amperage from the set. This is why covering up one small corner of a solar panel can cover one cell in series and drop the amperage of that particular cell to 0, which makes the entire string take that low 0 amperage value. This may drop the power that the panel produces below the operating level of the appliance which is why it turns off from a small bit of shade on the panel. To avoid this, make sure your solar panels are always placed in a bright, sunny area that is free of obstruction and shading from trees or any taller objects as the sun moves across the sky.