As I said in another post, the powers of all the races have their own source of power, escanor's source is the sun, unlike the others sources of power, the sun may only give power to escanor that is why he is so strong, he is getting all that energy just for himself
Maybe the sun is not great entity as the others(the source of miasma or the source of angels power), it could be more like the sacred tree that could become a strong entity capable of sharing it power(not like demon or goddess entity or gods), the only diference is that the sun is far more powerful than the sacred tree(but not than the demon's or goddess)