I am having a hard time following your logic ........
Might be from a day of fun in the sun boating
MPPT
Input - "Watts" no neeed to match the nominal battery voltage as with basic PWM contollers. Figure things in watts not amps or volts but the combination of the two WATTS
Output - Battery charging current using the traditional PWM methods nothing special there
As stated earlier
TriStar-MPPT-45
• maximum 45 amps continuous battery current
• 12, 24, 36, and 48 Volt dc systems (house battery voltage, 45 amps into a 24 volt battery bank 1,080 watts)
• maximum 150 Volt dc solar input voltage
• RS-232 and MeterBusTM communication ports
TriStar-MPPT-60
• maximum 60 amps continuous battery current
• 12, 24, 36, and 48 Volt dc systems
• maximum 150 Volt dc solar input voltage
• RS-232, EIA-485, MeterBusTM, and Ethernet communication ports
NO we are not saying a 45 amp controller is limited to 600watts with a 24 Volt battery (that limit is 1,200 watts), Yes we are saying (a quote from the MS specification sheet) that using a 12 Volt battery anything more than 600 watts of PV array is gaining you NOTHING and considered a poor design with zero built in headroom - the controiller limits it's output at 45 amps to the battery.
The array voltage has close to nothing to do with the battery charging current. Array voltage should match battery nominal voltage with your the basic PWM controller. Between the PV array and the battery charging current sits the "Buck Conversion stage"
Please explain how MPPT controllers "CLIP the amps"
This doc might be of some help
https://docs.google.com/file/d/0BxN-ydf9Fcj-YWhSVi10RFJxQ0E/edit?usp=sharing
