When a Victron 100/30 charge controller says it is rated for 440 watts at 12 v or 880 watts at 24v is it referring to the solar input voltage or the system output voltage?
To maybe clairify
Can I only run 4- 100 watt 12v panels?
Or, can I run run 8- 100 watt wired 2S4P?
If the latter is correct, wouldn't a Victron 75/10 work for this 30v/250 watt panel for $110
Yes thought I already made it clear, ideal value is one 75/15 per 250W panel, 1:1 ratio.
Unless somehow 100/30 were close to the same price, or you don't mind wasting the extra money. Forget about adding more panels later, stick to 1:1 ratio.
Between power and current, the **primary** rating is Amps, and that is maximum Amps **output**, multiplied times battery charging Voltage is how approximate max output Watts is derived.
By definition, input power **has** to be greater than input, and in fact, unless you go **way** over on watts input - which Victron does give plenty of "overpanelling" headroom - you will only very very rarely see the SC ever get to rated output in real life.
So with a 12V system, that 30A rating means "around 440W" depends on charge voltage.
The rated (theoretical) watts of the panels could be 500 easily, even 600W, and that overpanelling **greatly** increases the **average** Ah charging output per day per controller.
The only time the panel's higher output gets "wasted" is in rare peak conditions, when your bank is likely to have been fully replenished long before sunset anyway.
The Watts output from the same Amps, doubles going from a 12 to 24V bank.
Hope this helps.
