An important advantage of crystalline solar cells is that they are more efficient, but the crystals take long to develop and that adds to their cost, making them more expensive. On the other hand amorphous silicon panels, devoid of crystalline structure, are economical to produce, though not as efficient. Some manufacturers of solar energy panels use a combination of both the types of cells to derive optimum output. The more efficient crystalline silicon variety is used to capture most of the energy in conjunction with the layers of amorphous variety that captures the leftover part, thus making optimum use of both the verities.