In Iberia it might depend on who was prepared to invest in the infrastructure. In certain districts of the Frontera, even as it shifted south, there would be an band of country where raiding meant it wasn't worth the investment in infrastructure, or even the crops, hence the focus on sheep ranching.
Im northern Europe it was pioneering monasteries, often of the Cistercian order, who invested in water mills. Perhaps the religious orders took a similar lead in Christian Iberia.
The famous windmills that survive are in La Mancha which wasn't 'reconquered' (other verbs are available) until the late C11th. Being a notoriously dry region, reliance on windpower may have been more essential than in the reasonably well-watered south.
On the Arab side, I am not sure what the landholding arrangements were. Some water powered mills would have dated from Roman timess, but the systems still had to be maintained.
Certainly, windpower is very popular in southern Spain today! The valley where Sir James Douglas met his end is hemmed in with torbinas like flashing spearpoints.
Apologies, forgot this was an C18th thread