Rule of thumb is that in good conditions you can estimate solar panel power output as the rated output for four hours each clear day. Figure six hours a day if the panels are adjusted to track the sun.

Practical usable power from battery banks is typically a third of their rated charged capacity in amp/hours. A bit more if you use batteries with friendlier charging/discharge curves, a MPPT charging system, use twelve volt output directly or a high efficiency inverter. But seldom do you get more than half without shortening the life of the battery bank.

That isn't the final word, and such rough estimates won't replace a detailed engineering study, but it is remarkable how many times such a quick and dirty estimate is within a few percentage points of some very expensive professional analysis.