"Larry Jaques" wrote in message
...
On Sun, 05 Nov 2017 07:37:28 -0800, Larry Jaques
wrote:

On Sun, 5 Nov 2017 08:09:56 -0500, "Jim Wilkins"
wrote:

from a small system. My DPS5015 switching regulator can be used to
find and charge at the maximum power point but it won't track
changes
automatically.

Interesting, but sort of a moot point without automation. Or is it?
Finding the MPP of the system might be good for a boost, even
without
the tracking, but I haven't seen any studies on that. I'll look for
some more articles on MPP to see.

Nope. Conditions vary so much that a single snapshot of an MPP in
time wouldn't be of much use. It appears that the MPPT controller
changes the resistance of the circuit so it continues to output max
power at all times, from 1 to 1000 times per second. (one of 84
million 400 thousand snapshots a day.

https://www.teachengineering.org/les...pveff_lesson03
(I know, k12 site, but it had the info I sought.)

I made that measurement on my HF 45W panels with a large rheostat and
a DC Volt/Amp/Watt meter and found a range of several volts where the
efficiency was at least 95% of the peak.

Batteries charge with Amps, not Watts. Any charging voltage above the
12.6V that the battery gives back is only a lost entry fee. The graph
shows that the current continues to increase as the load (battery)
pulls the panel voltage further below the Maximum Power Point.

The DPS5015 displays output Volts, Amps and Watts and with another
wattmeter like the blue Aode in the input, the output can be adjusted
for the maximum charging current reading, then you can compare Watts
in and out to see efficiency.

-jsw