Hi,
I got 1 of these 650w bifacial panels. Did a test to see what I can get of them. I used a multimeter to test from around 10:00-14:00. the voltage seem good 47v. The amp seem very low 4.2
converting to watts it seem very low for a bifacial, from just under 200-220 watts during peek.
I’m not an expect in any way but I would have expected much more.
How did you load the panel for the performance test?
What MPPT and was the battery/BMS able to accept full charge at the time?
thanks for the response.
That is what I’m trying to understand.
Is testing just with the multimeter accurate to understand the performance?
The panel is not link to any system.
What will I need to get the actual watts output?
If anyone can help me better understand how to perform these types of test please. Will appreciate.
You would really need to test the panel by using it to charge a battery using an appropriate mppt. I’m surprised you even got 200w. It needs to have a load attached to give you the correct volts, amps and watts readings.
thanks.
That is perfect. That is what I’m trying as a DIY project.
will this MPPT work?
Upload the specification sheet for the panel first - that will give us important info to size the MPPT
If you are just testing with a multimeter, you are measuring Voc (open circuit voltage) and Isc (short circuit current).
Voc measured should be very close to the label (above), and is.
Isc should be 70%-80% (depending on how far South you are) at noon on a cloudless day.
These two numbers should give you an idea of how close to specification the panels are performing.
But as mentioned above, the only way to determine Maximum Power is to use a Maximum Power Point Tracker (MPPT) to load the panel to the optimal point and measure the power output.
True, but I would say that if the spec says 18A I_sc, and you are getting only 4, then either the panel is not getting proper insolation, or there is something wrong with it. If you put it in bright sunshine at noon, you should be able to get 12A to 14A on a dead short.
that is correct. The Voc is close to specification. It’s the amp I’m unable to figure.
below is the multimeter I have.
Is there a way to get a Isc reading?
that is what I expected. something around 10A-14A on the multimeter.
Is the setup correct to get the amp reading?
Plug the black probe into ‘COM’ and the red into ‘20A’, then measure across the panel terminals in direct sunlight.
IMPORTANT: When probe is in ‘20A’ or ‘mA’ socket, it is placing a dead short across the probes. Remember to plug it back into the ‘V/Ohm’ socket before measuring anything else!
Yes, that looks much better! Thanks @justinschoeman for answering his questions, I was about to type an answer but ended up in a slightly prolonged but important phone call before I could.
If the panel does over 10 amps and the sunlight is not perfectly clear, it is probably working just fine. But as mentioned earlier, to get an actual peak power reading, you’d have to wire it up to an MPPT and a battery.
One more note about using the 20A range on most DMMs (digital multimeters)… they can measure high current only for a short amount of time. So perfectly fine to measure a panel like this, but don’t keep the meter connected for prolonged periods. It is just for checking.
Also, never attempt that with a battery. Solar panels are designed to run permanently at very close to their short circuit current, and you know roughly how much it is going to be (from the spec on the back). If you did this with a battery, you will have a very large spark and possibly a blown meter. If you are lucky, just the fuse in the meter… but probably the whole thing. Hence the recommendation to always return your red probe to the right-most position immediately afterwards, so this does not happen accidentally.
Edit 2: Thought I’d make a bit of video content also demonstrating a feature of your better meters.
thanks all.
That was a great help.
@mmaritz thanks
@plonkster thanks
@justinschoeman thanks
Panels are rated at 1000W/m2.
So a 2m2 panel (excluding the frame) at 21.5% efficiency would be 430W.
Higher than 21.5% would be an exceptional panel in 2024.
A 650W would have proportionately more area.
I think your panels are too small to be 650W.
Secondly, the meter required is one of these:
Remember that these are bifacial panels, so you effectively double the surface area.
Peak power ratings of bifacial panels are usually calculated with the TUV recommendation of 1000W/m2 front and 300W/m2 rear. So rated power is about 1.3x a single sided panel.
Of course, how much power you get from the back is extremely installation dependent, and often close to 0 in most situations.
thanks, I’m learning tons with the support.
Would that mean that the test I conducted would be void or still have some % accuracy?
Bifacial panels do make it a bit trickier.
If there was little light on the back of the panel when testing, then you could expect a maximum Isc of around 14.4A. Then you also need to compensate for exact altitude, latitude, position of panel, position of sun, etc.
Assuming the panels were well orientated, close to solar noon, then you could expect maybe 70%-80% of that. So 10A - 11.5A.
So, if these assumptions are correct, then your measurements are about right for the panel specifications, and you can probably expect real output of around 350W-400W from the panel.
