To determine the number of solar panels needed to run an off-grid water pump, you will need to consider the following factors: - The size of the water pump: Water pumps come in a range of sizes, with different flow rates and horsepower ratings. The larger the pump, the more electricity it will need to operate. - The amount of water that needs to be pumped: The more water that needs to be pumped, the more electricity will be required to power the pump. - The available sunlight in the area: The amount of sun available in the place where the system is located will affect the amount of electricity the solar panels can generate.