See post #23 and #32
You said it was Clear.
So i have to find the max power point manually with a rheostat for a configuration (ex: 1 panel 12v 350mA) and make automatic measurements during the day in that load point found.
Then repeat all for the second configuration to compare (ex: 30 panels in parallel)
Finally i can compare the efficiency of 2 configuration.
Maximum power point load is changing during the day because panel mpp current is changing. Only thing static(almost) is mpp voltage. So if you find maximum output load of x amps at noon and you apply that same load at late afternoon, your panel output collapse completely.
I have application where I want to get max juice out of the panel all day long. So I have variable load which is regulated based on panel output voltage. I'm monitoring only voltage, If voltage is lower than Vmpp I reduce load, if higher I raise load. Basically same what commercial MPPT charge controller does.
I still don't understand what you are you willing to do exactly, but if you want an easy way to experiment with your panels output, I can recommend some cheap variable voltage/current power suppply like this:
EDIT: I just looked at your panel specs, this converter is little bit small for your panel max output 120W.
This would work.
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In your application the regulation of current in dependence of voltage is made by hand or automatically (commercial mppt) during the day?
About XY6020L device i have to put panel voltage in input and setup voltage ref to Vmpp? Device regulate current in dependence of panel voltage varations.
Mine is automated.
I'm not proposing you to invest $30 for that power supply, if you don't need it for anything. But it's easy way to regulate load and observe how panel responses. And according to specs, you should be able to use it with 4-5 12V panels in series
You should put one panel in input, some load in output (for example 12V, >150W heating element or halogen lights)
Set output voltage to 10V (since xy is step down converter)
Set output to CC mode and start raising current up from 0, following output power on display, continue raising output current until output power doesn't raise anymore and starts going down. That's your max power point. Now if you set the display to show input voltage, you will find your real Vmpp
Might be completely useless for you, if you explain what's your target, I can give better suggestions.
I want to compare a configuration with 30 panels (0.35A, 12V) in parallel = 10.5A, 12V, 126W
with a configuration with a single panel 0.35A, 12V, 4.2W (https://www.amazon.it/NUZAMAS-pannello-sistema-Camping-caricabatterie/dp/B075LYJF67)
Panels in first configurations are in different conditions (dirty, aged, broken..)
For compare i need to measure power of each configuration every 15 min for all the day.
I think that mppt solution is the best one or i can measure current Icc without load with a INA260 or ACS724LLCTR-10AU
I suggested an automatic device 5 days ago in post #25 but you did not seem interested.
Are you looking for something cheap, using an arduino?
If it's just a test bench and you don't need to power anything from the panels, you only need to find panels real Vmpp and then measure Isc every 15min. From that you can estimate max power available at that moment.
are these devices automatic (like an mppt)?
Can you suggest someone to see the costs?
I'm using an esp32
Yes, but current sensors on the order of 10A are hard to find or take a long time to ship. Now I'm seeing an ina260 on aliexpress
Just remember, that you can compare two setups measuring Isc. But to measure Impp and max power you need carefully adjusted load.
yes, but i don't need max precision but a realistic comparison between the two setups
Is your device bought or made by yourself?
What is your budget?
Self made.
If your comparison is like setup1 has xx% output of setup2, Isc is all you need.
If you need to know max power (Vmpp and Impp) of a chinese undocumented panel, you need to measure it, otherwise you have too much uncertainty to estimate anything.
about 50 euro
essentially the first but i'm curious if I can build an mppt like you did
Sorry, nothing in that price range.
So do the essential first. After if you have time and budget, start experimenting further.
Thanks, of you'd share tour project i'll appreciate!