Solar Charge Controllers High Capacity

High End Solar Charge Control Systems 100-300 Amps

MPPT charge controllers are amperage limited and voltage tolerant.  Higher the voltage of the array and higher the battery bank voltage will allow more controller capacity.  The capacity of an 80 amp MPPT charge controller in a typical maximum 150 volt system works like this.

• A 12 volt battery bank is limited to about 1,500 watts of solar panels
• A 24 volt battery bank is limited to about 3,000 watts of solar panels
• A 48 volt battery bank is limited to about 4,500 watts of solar panels

If you have a large system that needs more energy, 80 amp charge controllers can be "stacked" or combined to provide more charge amperage.  Each controller needs its own array based on the above limits.  As many as 10 controllers can be used to charge the same large battery bank.

This is more cost effective and has the benefit of redundancy compared to the few very large charge controllers that can handle up to 300 amps from a single array.  300 amps using multiple 80 amp controllers will cost less than $3,000.  The largest charge controller we know about costs over $5,000.  If the $5,000 controller goes down you are out of business.  If one of the 80 amp controllers goes down, you still have 75% of your charge capability.

The best way to handle larger solar arrays being used to charge a big battery bank is to refine your array wiring to maximize the array voltage and minimize the array amps.

For example, 18 each 250 watt 60 cell modules wired three modules in series and 6 strings parallel will result in an array maximum power voltage of about 91 volts and about 36 amps.  I have seen my own arrays generate as many as 112 volts, usually on partly cloudy days where the "edge of cloud effect" increases the intensity of sunlight.  Solar panels increase in efficiency the colder they get.  If you are in an always warm climate you may be able to wire 4 panels in series, saving wire and circuit breakers or fuses.

This scenario above will work for charging a 48 volt battery bank using a Midnite Solar Classic 150 MPPT or anOutback Flexmax 80 amp controller.

Morningstar has recently introduced a 600 volt 60 amp Tristar MPPT charge controller which will allow 12 to 15 each 250 watt 60 cell modules to be wired in series in one string, saving array wiring expense and combiner and circuit breaker or array fuse expense.