Gebrauchte PV Module mit Multimeter testen prüfen

now here in my video how I proceed. The first thing I do is a sight check and I look at the module here very closely, also here, whether water has already penetrated, i.e. whether there is already rust or other things, whether there is something like that, then also whether the glass layer is broken, whether there are jumps on it, etc. Now I look very closely, I look at this, this, this, up here too, whether the edges also fit, has it fallen down somewhere, just take a look at the edges here and of course also how strong the corresponding pollution is. Here with this module, for example, you can see spiderman app, as it is so beautifully called, so here everything is crumpled and you can already see that there are slight water deposits in it and you can also see that the edge is already off, so you can see the state of care, then as it has been treated, there are green spores somewhere, i.e. moss deposits if you see something like that. This is the first thing I look at when I check the visibility of such modules. So we measure the idle voltage, how do we do that? We set our voltmeter to voltage, equal voltage and measure the corresponding idle voltage. We see here, we have 30 volts here, now we can compare what is on the technical dashboard. 30 volts open circuit voltage, fits. The next thing we want to measure now is the short-circuit current of 7 amps. To do this, we have to go to DC current with our ammeter and also plug it in accordingly. Once on common here, once on 15 amps. So, we have plugged in here and we measure 6.4 amps here. Yes, well, the alignment may not be ideal here, but that should be pretty good now. We have to get to the short-circuit current, 7 amps, and now here 6.6. That's fine. A guideline for a PV system looks like this. This is the current axis, this is the voltage axis. And you have to imagine that the product is made of voltage and current, so this here, if you do it like this, then the area of ​​your power corresponds. There is also this Maximum Powerpoint Tracker, MPPT. It is looking for the maximum here, so that the maximum area is here. The problem with our multimeter is that it can't do that. But by installing a resistor in our circuit, we apply a fixed working point here. And how big the resistance is, by the way, a short excursion, how can you calculate that? So, you can also calculate the ideal resistance by taking the open circuit voltage from 30 volts to the square and then divided by 160 watts. So, then you come here to 30 to the square by 160 and then the optimal resistance would be 5.625 ohms, in our case 4 ohms. Well, as I said, it's just a thumb adjustment. So, in our case we have 160 watts times 4 ohms resistance, then from the roots, results in a voltage of 25.3 volts. We would have to have that here at the resistor, then I can assume that I have around about 160 watts. Probably, in the ideal case, I will have around 20-21 volts. And yes, make sure that you have the optimal inclination towards the sun, no cloudiness, and then you should be able to read the corresponding voltage values here. The problem here is that you don't like cloudiness at all, so everything is dead here. And then, I would say, around 80%, between 70 and 80% of the 160 watts should be reached here. And then you can say, if you have calculated these three measurements, i.e. idle voltage, short-circuit current and this performance measurement, then you can say, okay, modules are fine and you can buy them nicely. So, then we work with a 4 Ohm resistor here. We connect it to our system here and in the next step we measure the voltage over here. We have 20 volts here and now we can use the formula 20 times 20 is 400 divided by 4, which makes a power of 100 watts. This is now for the actual season, for the slope. Well, it's not optimal, but you always have to say it that way. And you can see, the part here is getting very warm. That's what I've done here now. It's about to start glowing here because it's only 500 watts. So, the module has performance. Yes, you know it, it got cold. I put on my famous fiber coat jacket again. Briefly to the conclusion of the whole measurement. If you do the three measurements plus the visual control, then you already have a very good impression of how the system is together. What you can't measure so easily is things like insulation resistance of the module. It's difficult to do anything with my measurement setup here now. I take the ideal maximum power point, so the optimal performance. I only have one working point here, a 4 ohm resistance, to determine. Then there are corresponding measuring devices where you can test PV systems or modules, to put it mildly. If you are interested in something like that, feel free to write it in the comments, then I will get such measuring devices. Maybe it's not a shame if you have something like that. Otherwise, now I would be happy at the end, what other ideas, suggestions do you have, what you can measure here with household multimeters, to recognize a used solar module, whether they are good or bad. Feel free to write in the comments below. I am happy if I can learn from one or the other. Now I wish you a nice day, thumbs up, feel free to subscribe, here you go on with another cool new video. See you, bye.