To many panels for charge controller

[WindriderNM]

I am getting ready to install a solar system. I have a lot more panels and I need to charge the batteries. I have an 80 amp charge controller. I would like to use the extra power during the day to run a swamp cooler, washing machine, and tools. If I have more then 80 amps going into the controller will it fry? If so I was thinking of putting a diode between the extra  panels and the controller to battery cable this point would also go to the inverter. I have a 240 amp 40 V diode. The panels are 24 V.

[bob golding]

use two controllers and split the panels into two sets. that is what i am planning to do with my system.

[Bruce S]

Mostly I would go with what Bob says.
BUT if you're the adventurous type , you could use a diversion controller (GHURD style) you could set it to begin siphoning off the extra to run the swamp cooler. There are older pots showing lots of different routes. HK even built his SMD via the info from GHURD.
Just a thought.
BUT!! To be safe the dual controller method would be best as you could fry the single controller with too much power hitting it.
 

[OperaHouse]

I had a similar problem with my system for a couple years.  I had three Morningstar 10A controllers and more panel capacity than they could handle.  I used the excess capacity of my UNO fridge controller to turn on and off a FET connected to the extra panels.  Any time battery voltage dropped below 14.2 volts the FET would turn on.  This decision was made about every quarter second to prevent turn on/off heating.  The FET assembly was cut from an old UPS and easily handles 30A with no heating.  Easy to build and costs only about $10.

[jack11]

I've been wondering the same thing, potentially damaging the charge controller when too much PV array power is connected to it.

The Morninstar people tell me that their ts-mppt-60-150 controller is self-regulating as far as the amount of current it takes from the array (assuming the max array voltage does not exceeded 150V for all conditions). There is no reference to the max array Isc in their manual. So, I guess you can hook up as much PV power to it as you want, without damaging the unit. I think they regulate the amount of incoming power by the heatsink temp derating. They limit the battery current if the temp gets too high, which should also limit the amount of incoming current from the PV array.

On the other hand, Schneider Electric has a hard device-damage limit of 60A on the array Isc going into their mppt-60-150 controller stated in their manual (of course they also limit array Voc to 150V). They also do the heatsink temp derating, but want you to externally limit the incoming PV power regardless???

Is anyone familiar with this charge controller PV power self-regulation vs. hard limit tradeoff, and can comment on this?

[hydrosun]

You idea of bypassing the controller would work if you have enough dump load to use all the excess power. If the voltage rises the controller will begin to shut off that solar array. I have some of my panels direct to batteries with dump loads keeping the voltage down.
Chris

[birdhouse]

yes, i've also watched a video from a tech at morningstar.  he speaks of how the ts-60 mppt 150 can handle more amps than 60, however it will only push 60A into the batts.  he doesn't say exactly how much more.  it seems as though there should be a limit?   

it's a nice feature if you want to over size your array for cloudy days, especially if 60A is plenty for the sunny days. 

adam

http://www.youtube.com/watch?v=5H_B7PmA2wE

it's somewhere in that hour plus video. 

[jack11]

this is a good video. I think they programmed 80A as default into my ts-mppt-60s, but if you change the settings in any way then they only let you put in up to 60A for max battery current.

the oversizing of the array wattage is good for cloudy days, as well as for keeping spare panels working for you. I've been thinking about switching the excess strings in/out using a relay driven by an auxilliary output that can trigger from a low value of PV current (indicating cloudy conditions). This way the 60A Isc limit is not exceeded, and the control is automatic to switch out the excess panels when the clouds go away. The Schneider Electric controller has the programmable aux output, Morningstar does not.

[john8750]

I would think the only problem would be wasting power after the battery is fully charged.
 As long as the CC can handle the full load battery charge, use a fuse, should not hurt controller.
I like the idea of the mosfet switch controlled by a comparator circuit. Would set it for above 13.3 or so. I also would not run anything other than say a resistive load without a battery connected. No motors or CFL's.
These are my thoughts, may not be science!

John Smith