It's just ohm's law... 140A on the label of the welder does not mean there will be 140A flowing. It is just the maximum the welder can deliver. The welder supplies a certain voltage, the load (the charge controller in this case) will dictate how much amps there will be flowing. As long as it stays below the 140A the welder can deliver.

Victron say as long as the input voltage is under 100v, you can input as many watts as you want, but the controller will limit the ouput to 50amps on that model. They 'recommend' oversizing the panels by up to 130% to what's stated as the maxium pv input, but I think this is just for warranty purposes.

Thank you for this test and other people's comments, I have wanted to know just how much I could over panel by, and it looks like no limit Thanks Richard

I should add, if you run too "much panel" on a MPPT controller you may get shut offs during transient events, such as full sun coming out from behind a cloud, as the controller cannot change it's transfer ratio quick enough and an overcurrent or overvoltage event leads to a shut down. You can't run with too much series panel because the maximum panel voltage must stay within the voltage rating of the unit (100V) and that voltage is going to be generated under the higest insolation. You can run with "too much panel" in parallel, other than the usual issues of ensuring panels stay forwards biased etc

It's right in the title of the device - 50a on battery side -

An MPPT controller is just a non isolated BUCK DC DC converter. It uses an inductor and a power switch to voltage match between the panel voltage and the battery voltage. The power and current limitations come from the current density limit in the inductor and the thermal limit of the power switch primarily. Power out = Power in - losses. In this case, the inductor & switch cannot handle more than 50A continously and less than that if they get hot, as the unit derates as it heats up btw, lowering it's current transfer to prevent thermal runaway and failure. The maxium 50A output into the maximum battery voltage for the unit sets the absolute power limit, and the unit will simply "throttle" the solar input (by moving away from the maximum power point) to keep the current at the limiting value. In your test your welder is effectively a constant voltage source, and your battery another constant voltage sink (for the duration of this short test anyway), so the controller will simply ramp up the output voltage to a voltage above the battery voltage by an amount that drives the maximum allowed current into the battery but no more. If you look at your test, you'll see the output voltage was higher for the 25A output test than for the 10A test because of the resistance of your battery and leads. With the unit attached to your welder, all it did was to change it's voltage transfer ratio to push up the input voltage, meaning the current that was pulled from the welder falls. iirc, the 48v output MPPT from victron can go up to around 60V maximum, so at 50A that's an output power for a single unit of 50A x 60V which is 3000W. On a 12v nominal battery system, then output power is of course much less at the same output current, ie 50 x 12 = 600W. For maximum power transfer you want the highest possible battery voltage and ideally you want a transfer ratio as close as possible to the minimum step down ratio, but because this unit is only a buck converter architecture the input voltage from the panels must always be higher than the output battery voltage by a margin

You donot PUSH amps. Amps are drawn by the apparatus that is connected. With the Solar controller you are limited with the amount of VOLTS you supply to it.

I always thought the 50a was to the battery not pv side amps.. I don't think the controllers are based off pv side and the pv side is very high amps it's just limited by voltage. My issue is i got a 100/30 and using my 300w 70v solar blanket in summer in 2022 at midday i got 301w 72v but i then tested it on the same date a year later and only got 180w 56v..nothing has changed on the controller only thing i changed was added a second battery but all settings are fine..but i cant understand how it works when i test with multimeter at the panel i get 73v and 4.4a when i test on the pv nuts it goes to 56v 1.4a...like wth i checked the cables and all fine i even cooled the panel but same results..why a massive drop

you can connect more it norally will only take its througgh put power, but you should fuse the input incase of malfucntion or pv sweep, it can cause a fire

Nice, ... but the voltage input can't go over the 100V ... Right ... ???

wait what? did you mean to dump 140amps into the controller? says on the spec sheet no more than 60 amps in from your PV. Cool to know its working ok, but that might be just because its a well built unit - could crap itself eventually. I'm pumping 2400w into my victron 100/50 - no dramas. 4 strings of 300w pairs - 70v x 32amps.

the solar controller will only "drink" as much (voltage less than 100 volts @ given amps available) as it takes in order to make a voltage of 12/24/36/or 48 @ 50 amps You can have a billion amps of power @ 90 volts and the solar controller will only drink what it can consume. You cant "force" amps into it. Imagine plugging in a small fan into your wall outlet. There is way more available amps in the outlet than your fan can consume.