Sizing a solar string means matching how many panels you wire in series and parallel to what your MPPT charge controller can safely handle. Get it wrong and you either under-produce or destroy the controller.
Panels in series add voltage. The critical limit is the controller's maximum PV input voltage. Cold panels produce higher voltage — the panel's open-circuit voltage (Voc) rises as temperature drops. Standard practice applies a 1.15 cold-weather multiplier to Voc before comparing to the controller limit.
Parallel strings add current. The combined current must stay within the controller's input current rating, with the usual 1.25 safety factor for continuous operation.
A panel with Voc 49.5 V, Vmp 41.5 V, on a 150 V controller:
Always confirm exact figures against the panel datasheet and controller manual — both vary by model and site conditions.
Preliminary design information only — final systems must be verified by a licensed electrical contractor.