On Tuesday, January 5, 2021 at 8:57:17 PM UTC-8, Eric Greenwell wrote:
2G wrote on 1/5/2021 6:52 PM:
On Tuesday, January 5, 2021 at 4:58:48 PM UTC-8, Eric Greenwell wrote:
Dan Marotta wrote on 1/5/2021 10:48 AM:
On 1/5/21 11:41 AM, Eric Greenwell wrote:
the ones for gliders are usually chosen to optimize charging of 12 volt batteries with PWM
charge controllers, and using an MPPT controller on those panels will gain little extra
charging.

I'd like to see a proof of that...

Which statement: glider panels chosen to optimize PWM, or MPPT controller won't help with that
type panel (ie, low voltage output)? In general, though, the big difference is PWM is more
efficient with low voltage panels (like 18 volts), and MPPT is more efficient with higher
voltages (at least 24 volts, 30 is better).

Do you have the specs for your Stemme panels?
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

That doesn't make sense: an MPPT controller IS a PWM power converter, it just optimizes the operating point.
https://www.researchgate.net/profile...controller.pdf

The advantages of a higher voltage panel a
1. Lower percentage losses in the MOSFET switch (not much of a factor).
2. Wider operating point to deal with less sunlight.

Tom
An MPPT charge controller includes a DC-DC converter (called a "buck" converter in the paper
you reference) to convert power at the MPP voltage to the battery voltage needed for charging.
A PWM charge controller, in the context of solar power systems charging batteries does not have
the DC-DC converter. It just switches the panel on and off to the battery - no power conversion.

Here's an example: My motorhome has two 100W panels in parallel, producing about 11 amps
charging in good conditions. If I were to put the panels in series while using the PWM
controller, the system would produce about 5 amps. If instead, I used an MPPT controller on
that same two panels in series, it could produce about 14 amps of charging.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

A dc-dc converter IS pulse-width modulated (PWM). A series switching MOSFET is turned on and off (pulse-width modulated) to regulate current in an inductor. Here is an excerpt of the article I referenced:

" Then depending upon power level it gives PWM input to buck converter which
decides whether the solar panel is to be connected to battery or not for charging."

Tom