It WORKS! 40 amps DC tripped a 20 amp AC breaker

[kalakoa]

MPPT controllers function by maximizing the amount of energy that goes to the batteries

Most MPPT controllers also detect battery voltage drop due to load, and respond by harvesting as much power as they can handle, so you can use the entire panel output.

[MattKarma]

The C-40 attempts to maintain charge at whichever voltage it's charging at. It doesn't see "load", it sees the voltage drop and attempts to maintain constant voltage (assuming excess power is coming in). Most panels are designed to operate with 24V controllers, higher voltage goes farther, and it's like "What ... do you live in your CAR?".

lol.

Some loss due to resistance 30 V vs 150V ... lower voltage is safer, for the distance ~ 25ft loss isn't very large.

There may be economics which support using MPPT for larger arrays. Definitely for grid tie.


***Still can't figure out how to spell 'car' correctly***

[kalakoa]

Most panels are designed to operate with 24V controllers

I have several 18V panels. These might work with a 12V controller. but at the expense of losing 30% of the wattage.

I have several 25V panels. These might work with a 24V controller, but the batteries would never reach float voltage.

Panels have since (mostly) standardized around a Vmp of 30V. Even so, a PWM controller can't make use of the entire output...

[terracore]

"I have several 18V panels. These might work with a 12V controller. but at the expense of losing 30% of the wattage."

You're talking about a PWM controller, correct? A MPPT controller should automatically down-adjust the voltage by increasing the amperage, therefore, no significant loss?

[kalakoa]

Correct: odd-voltage panels require MPPT to harvest their full output.

The design simplicity is just an extra added bonus.

[microage97]

By a real charge controller, like midnite solar 150. You will want to seiries (sp) the panels so the are almost the max of the charge controller. The controller will drop it to what ever the bank is, but will convert the voltage difference to AMPS.