Solar controller advice

[44'cruisingcat]

I got the Flexmax 80 because it was only a little more expensive than the 60. Didn't need the 80 amp capacity at the time, or yet but it allows for future increases if they happen.

[44'cruisingcat]

Originally Posted by CAELESTIS

Consider the Midnite MPPT "The Kid", or the Classic. Midnite was formed by the founders of Outback(prior to sale and subsequent move of manufacturing to India).

You can tell they're styled by the same people! Weird! The flexmax looks like a combustion heater, the Classic looks like some kind of 1940's radio.

[noelex 77]

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.