Switching between parallel and series connections (solar)

[Tom.G]

I would consider scrounging the high voltage electrolytic capacitors and diodes out of old switching computer power supplies.

I would recommend using Non-Inductive, Metallized FIlm capacitors rather than old Electrolytics.

Electrolytics fail with age by drying out, especially at elevated temperatures. They also have poor high frequency response, which they will see during switching transients.

Metal FIlm do not have that aging problem, they self-heal if they develop an internal short circuit, and the non-inductive ones have decent high frequency response to suppress the switching transients.

Cheers,
Tom

 

[Baluncore]

I would recommend using Non-Inductive, Metallized FIlm capacitors rather than old Electrolytics.

This is not running above 10 kHz in a switching supply. It may only be needed a couple of times each day.
The snubber does not need fast capacitors, it needs to ramp up voltage while current ramps down, and so prevent sparks. There is plenty of time and voltage headroom during the transient.
An electrolytic has distributed inductance and capacitance, a bit like a transmission line. If the inductance of the electrolytic was high, a parallel 10 nF ceramic could be connected in parallel, but that is what the first turn of foil in an electrolytic actually does.

Electrolytics fail with age by drying out, especially at elevated temperatures.

The capacitors in this snubber idle with no ripple current, so they will run cold.

I am advocating a cheap experimental solution that will work OK and do the job, rather than an expensive overkill on a military budget. Gold plating the electrodes and polishing electrons is not needed either.