Step-down converter instead a solar controller?

[ZEUS-FL]

I just purchased 3 Ecoflow 400W portable solar panels. I have 16 EVE 105ah in series (48V System) with a 200A BK BMS on it. To charge the batteries I use a a power supply normally that is feed by DC voltage from 12V-53V input and able to provide up to 2000W. Anyway. Since I do not have a solar controller yet, can I use a Buck converter step-down that that i have able to convert from 12-90V to 10-88V 40A 1800W ? will that be a problem? The plan is connect 2 panels in parallel and 1 in series to not pass the 90V since each panel I believe is up to 41V. having that setup will damage the panel? I am planning on buy a Victron Energy SmartSolar MPPT 150V 45A for this setup. So.. The buck converter will work?

 

[chrisski]

You could, but there is a risk at how much you trust buck converter. If that failed, You’d really need to trust the BMS.

With the trust in the buck converter, you’re also trusting it has a clean waveform. My issue would be as it approached the charge stage that it’s not pulsing rapidly above 3.65 volts per cell. I don’t know what the trigger time is for a BMS.

I used a buck converter to charge a new iPhone off a solar panel correctly, but after 1 trip doing that, the iPhone is too costly for me to risk keeping that up.

 

[efficientPV]

Buck converters usually expect a low impedance DC input and a connection to something that has significant capacitive input. Some mgf warn not to use them on inverters. This is because the capacitors on the board are only enough to make it stable. I would suggest adding extra capacitors to the input and output. People toss out numbers like 41V willy nilly and I don't know what that means, is that Voc? I use buck converters powered by panels.

 

[ZEUS-FL]

Very valuable both comments, Thank you !!!

 

[meetyg]

Using buck converter probably won't work well, because panels have a "sweet spot" (called maximum power point), which is a factor of voltage and current.
So if it works, you are probably loosing some significant power.

Also, you mention 2 panels in parallel, the. series with the third panel. Here you are losing power too. If you had a 4th panel, that would work out better, in 2s2p.

 

[ZEUS-FL]

This is how I end up.

 

[Sergio95050]

This is how I end up.

The "sails" will fly when wind will blow ...how you prepare for that ?