Relevant harvest information could be gathered from other PV owners in that specific area. There are many PV forums.
If the focus is on own consumption, and if there is no storage and the feed-in tariff is much lower then the feed-out tariff, an optimal configuration is not to adjust all panels to the south, but to have the panels cover a wide angle from (south-) east to (south-) west according to the daily own power consumption mimic and the tariffs.
That way the power production will better match the demand and sets of panels like the most east and most west ones could be switched in parallel saving inverter costs.