Battery / Mppt charge controller question

[terracore]

If a solar array exceeds the rating of the charge controller by a few amps on those rare sunny days, does it fry the controller or does it mean the extra amps aren't used, or both?

[kalakoa]

Really depends on the specific controller and the battery voltage.

[Mikites]

Your going to have a hard time getting a straight answer from anyone, especially the manufacturer.. From a safety in engineering aspect the short circuit rating of the controller and array is more important than the wattage available.

One practice that is used in larger installations is to arrange the array in multiple orientations to limit the available current at any time while improving the output consistently from sun rise to set. Meaning, arrange half the array to collect more morning sun and the other for evening, at no point would the entire array be capable of the theoretical max output.

I’m just throwing out some suggestions, your exact system details need to be considered to make an action plan

[Bullwinkle]

fuse it

[randomq]

Tracer 4215BN MPPT manual says it can be overpaneled to somewhat less than 3x capacity, as long as you stay within the voltage limits. YMMV.

[terracore]

Thanks for your insight. I wonder what the "penalty" is for going over amperage, is it just lost solar opportunity?

[Mikites]

Typically yes, you would simply have more power available at the array than you can harvest. If your off grid this happens every full charge cycle anyway

Manufactures come up with max input ratings for a reason. Though strangely enough most will not disclose what they are and will only list the max output rating.. FYI the Outback flex 80 has a PV max short circuit input rating of 64A if that helps

[terracore]

Thanks everyone for guiding me in the right direction. I was able to find the specs online (not sure why they didn't include information with the unit) and the array can indeed be 3 times the output rating of the charge controller.

[randomq]

Maybe we have the same controller! I'm happy with mine, and notice that it's still for sale while others have come and gone.

At some point I will overpanel this one to deal with all these dark and rainy days. Kinda rough seeing 30 watts coming out of my 1000 watt array at high noon! For now we just avoid using the electric appliances and cook with propane.

[kalakoa]

more power available at the array than you can harvest

Diversion load is useful here. Most common is hot water; there are DC heater elements for retrofitting an electric water heater. If the inverter is big enough, you can also drive an electric water heater directly.

Pumping water up a hill can also be useful.

Not all storage need be in the form of electricity (batteries). Easiest if the controller has a "diversion control" output, otherwise use a voltage controlled switch (VCS-1AH or similar) tuned to the float voltage of your battery plant.