Interesting timing - I just finished a test of 30A MPPT & a 30A PWM close to their rated capacities - five 100 Watt panels in series for the MPPT & parallel for the PWM. The MPPT delivered 28.5 Amps to a 12V battery (battery voltage 13.5V) and the PWM delivered 30-31 Amps. This result is what I expected, but counter to what most people believe. There are several factors that determine the final current/power delivered to the batteries. I'll do my best to explain them below, but will not get into a pi**ing contest with those that argue.
Test conditions: SF Bay area, clear & sunny sky ambient temp 74F/24C. Sun nearly overhead. insolation 886 W/m2. Panel temperature 55-58C with a handheld IR temp gauge.
Equipment - five 100 Watt Newpowa panels, Interstate flooded cell battery partially discharged, Epever 30A/100V MPPT, 30A Bogart PWM, Fluke clamp-on & regular multimeters.
factors affecting a MPPT & PWM controllers' performance:
1) Temperature effect on the panel's voltage/power - Newpowa's derating factor is 0.5%/C. For my tests, this amounts (55-25)*0.5 or 15%. This alone hurts a MPPT controller's performance. A PWM controller is somewhat immune to this as long as the voltage at its input is higher than the battery voltage. A PWM sucks the Isc from a panel and Isc is typically 8-12% higher than the Imp. I suspect that in my tests, the bogart PWM could have delivered a little more, since its overcurrent LED was flashing.
2) Loss of DC-DC conversion efficiency. The 98% conversion efficiency typically quoted in product brochures is the peak efficiency.
At the rated max current, the efficiency drops off to 90-95%. Most significant contributor is the I2R power loss on the current switching MOSFETs & the inductor(s).
Additionally, the input to output voltage differential has a effect on the efficiency; higher the differential, lower the efficiency. Five panels in series takes the input voltage 70-80V range, with a corresponding efficiency hit. A MPPT is at its best efficiency when at the midpoint of its current specs (15A in this case) and about 2X input voltage (2 panels in series).
The Epever was taking in about 425-430 Watts & delivering 395Watts or about 8% loss.
I ran these tests for someone who was interested in it. I may repeat them with more variations (2S2p for the MPPT) LFP battery, etc. Did not have a chance to video them as I was working alone.
Moral of the story: PWM controller can do better than MPPT's under some conditions & vice-versa. Consider your personal case, instead of looking for a one size fits all response.
editing to attach a typical buck converter efficiency plot to illustrate the comment I make above.