Ah! The $64,000 question. The truth is that it depends on your circumstances and probably the opinion of the designer you speak to. Electricians Plus use Monochrystalline panels as they tend to give better performance in warmer areas. Monochrystalline panels are easily recognized from there Polychrystalline brothers by a 'uniform' appearance of the cells. they are usually black in colour. See the diagram at right.