Loud, I'm supposing that what you want for practical use is the ability to predict about what you are going to get from your solar array under your conditions, whether you are north or south at the time. There are bunches of variables unique to your setup. Perhaps the most practical approach would be an ammeter and a logbook, so you can record
power generated under specific conditons (latitude, sunny, at anchor
, month, etc.) at various times of the day. Within a year you would have enough data points to know the effect of a cloudy day or season or whatever interests you on power production, perhaps even as a percentage of your best case conditions.
Consider the possibility that using high tech ways of solving simple problems might create more barriers to your understanding your boat's solar system than they solve.