50 amp dcdc charger with mppt voltage requirements

[kingsling]

In the product manual for the charger it states that "Solar charging will be triggered if the PV input voltage is higher than 15V for 10 seconds."
Does this infer that : if you have two identical solar panels wired in parallel, with a VMP of 18.5 volts for each panel, and if it was a cloudy day or you were in a shady area and the VMP was reduced to 14 volts, you would get no charge to the battery from your panels at all?

 

[rickst29]

That's correct, although panel voltage is far less effected by cloudy conditions than panel current. And, if one panel is in shade, but the other panel is under moderately good sunlight, you will be seeing nearly all of the current from the favored panel, due to the presence of blocking diodes within the shaded panel.

In parallel, you obtain the sum of individual current amounts at the Voltage of the lowest panel.
In Series, you obtain the sum of Voltages, at the current of the lowest panel.

Combinations of Series and Parallel together (being an alternative when an even number of panels is involved, greater or equal to 4 panels) combines both limitations, from the bottom "layer" upwards.

This 15V minimum limit is typical for MPPT chargers charging 12v batteries - MPPT only works (converting power provided at higher panel Voltage into more current for the batteries, being provided at lower voltage) when it has a significant Voltage differential to work from.

 

[kingsling]

In the product manual for the charger it states that "Solar charging will be triggered if the PV input voltage is higher than 15V for 10 seconds."
Does this infer that : if you have two identical solar panels wired in parallel, with a VMP of 18.5 volts for each panel, and if it was a cloudy day or you were in a shady area and the VMP was reduced to 14 volts, you would get no charge to the battery from your panels at all?

That's correct, although panel voltage is far less effected by cloudy conditions than panel current. And, if one panel is in shade, but the other panel is under moderately good sunlight, you will be seeing nearly all of the current from the favored panel, due to the presence of blocking diodes within the shaded panel.

In parallel, you obtain the sum of individual current amounts at the Voltage of the lowest panel.
In Series, you obtain the sum of Voltages, at the current of the lowest panel.

Combinations of Series and Parallel together (being an alternative when an even number of panels is involved, greater or equal to 4 panels) combines both limitations, from the bottom "layer" upwards.

This 15V minimum limit is typical for MPPT chargers charging 12v batteries - MPPT only works (converting power provided at higher panel Voltage into more current for the batteries, being provided at lower voltage) when it has a significant Voltage differential to work from.

Thanks for the response, the Renogy has a 25volt max and a 15volt min, maybe I should keep on looking??

 

[John Frum]

Thanks for the response, the Renogy has a 25volt max and a 15volt min, maybe I should keep on looking??

KISAE DMT1250 Abso 50A DC-DC Battery Charger | DonRowe.com

The KISAE DMT1250 DC to DC Battery Charger is a multi-stage, multi-input battery charger capable of charging different types of batteries commonly installed in boats, RV's, 4WD's and commercial vehicles.

www.donrowe.com

Another option.

 

[sunshine_eggo]

That's correct, although panel voltage is far less effected by cloudy conditions than panel current. And, if one panel is in shade, but the other panel is under moderately good sunlight, you will be seeing nearly all of the current from the favored panel, due to the presence of blocking diodes within the shaded panel.

Bypass. Panels do not have blocking diodes. Those are in the MPPT.

In parallel, you obtain the sum of individual current amounts at the Voltage of the lowest panel.

maximum power point. Overlapping ranges of Vmp to Voc do not necessarily result in the array operating at the lowest Vmp. It will likely be between the two Vmp favoring the more powerful string.

In Series, you obtain the sum of Voltages, at the current of the lowest panel.

Yep.

Combinations of Series and Parallel together (being an alternative when an even number of panels is involved, greater or equal to 4 panels) combines both limitations, from the bottom "layer" upwards.

With the exception of the "lowest voltage" claim.

This 15V minimum limit is typical for MPPT chargers charging 12v batteries

"typical" is more commonly either Voc +2V above battery or +5V above battery (Victron). Once triggered most MPPT will continue charging with any meaningful power to be delivered.

 

[Bvillebob]

I'll just add that I have that exact Kisae charge controller / dc charger installed in my camper van for the last year and it's doing a great job, I've been very happy with it.