Originally Posted by Formosa Scott
Those were my thoughts when designing the system. I seriously doubt it will ever see 100%. What happens if it does on a 60a controller?
You will see 100%, or even over 100% under exceptional conditions. STC conditions under which the panel's are rated are bright but can be exceeded with direct light and reflected light from cloud.
Most (but not all) controllers will self protect if the current
is exceeded, but relying on this self protection mechanism is not wise in the long term.
In general I would suggest not exceeding the manufacturers recommended maximum wattage for the solar
panel array. Most controllers need derating for higher temperatures (this is hidden in the specifications). The maximum amp rating is a best case scenario.
The maximium solar
wattage (eg 800w for the Outback 60A) is more realistic, but even this is dependent on good ventilation and reasonable air temperatures which is not always possible on a yacht.
Feeding 915w of solar into a controller rated as a maximum input of 800w, as you are proposing, is a bit like occasionally over revving an engine
. It is likely to survive several years, but ultimately exceeding its design specifications will shorten its life. Given the relatively small increase in total cost going for the Outback 80 I think purchasing
the Outback 60 would be a mistake.