Hello
I want to use an available 48V input to augment the solar cell, when it's available. Can you give me an idea what relation the solar input has to the low voltage (battery gnd) output terminal please?
I've read elsewhere here that it's no good connecting the low-voltage solar input terminal to battery ground, but I'd like the official line on this.
The external 48V supply is from a SMPSU which has a floating output (only ground referenced by some small Y caps) which should be ok, but I ask as I have another battery-ground-common source available as well, however I can't justify going dc-dc with it just to isolate it from battery gnd.
Also, if I alternate between the panel and the 48V supply using a relay, there will be a brief solar input open circuit whilst the relay contacts travel. Will this cause the mppt to glitch do you think? Possible solutions include a small capacitor across the solar input terminals (0.22-0.47uF) to hold the input voltage for a mS or two ('dummy' panel) or instead, to common the low voltage connections of the 48V supply and panels, and diode sum their positive connections into the mppt solar input terminal. Both being high voltage sources (24V panel, 48V ext. supply, 12V battery) diode drops are irrelevant.
Your advice would be welcome.
