QUICK UPDATE: Your suspicions may have been right on the money, I’ve been checking my unit every other hour or so, since it stopped charging. Unlike most days with sun out, today however the INPUT Voltage was super low, ranging from (0.0 to 13) with the sun out unlike the usual (65 to 85) . Then all of a sudden late afternoon (3:40pm) I check the unit and see the INPUT Voltage has shot up to mid 90s (I’ve never seen Voltage that high for charging) and then it all of a sudden starts charging “100watts” (current weather: is windy with low sun, late afternoon 4:15pm, 13° Celsius).
It maybe an issue with a cable, connector or panel (possibly some high resistance somewhere in the setup), as you may having been suggesting
The multimeter should help me get to the bottom of this, my order couldn’t come soon enough… (I see light at the end of the tunnel)
Please tell me you did not mount a panel like this on your roof. If so I will need to pray for you lol. If you did, this is the wrong application. That thing would heat warp so badly I am surprised it even lasted as long as it did. The little box at the top is the junction box and if it fails, you will encounter high internal resistance.
R= I/V = 92V/1.03 ≈89.3Ω (since your unit was outputting 95W we know the amps is 1.03)
Assume it should output 10A @ 92V. 92V/10A ≈9.2Ω
So a factor of 10X more resistance.
It is normal for amps to be low, but that would be for normal things like if its shaded, the panel is extremely caked in dirt, or its cloudy outside. Once you know its high internal resistance then its a matter of finding out where. The panel. The junction box. The cabling, etc. A common mistake I see is improperly sized wiring for the appropriate cable run. Be aware though that you cannot test internal resistance from strictly the disconnected panels (open circuit voltage) with your multimeter. It won’t give you internal resistance results. Open-circuit voltage only tells you the maximum voltage potential with no current flow. Resistance requires some current flow, aka a load being applied to the panel. At a bare minimum you can use the multimeter to perform a short circuit current (ISC) test on the panel itself to see if its even capable of supplying current.
@sealy1986 I have 2 (545w Mecer Solar Panels mounted to the boundary wall of my property) with cables running underground in conduit pipes (PV cables 6mm - plus/minus 25metres) leading to my home office. (I opted for wall mounting because it’s easier to clean when it gets dirty or replace if it unfortunately gave out. I chose these panels cause they were very affordable with a 24 month warranty and (since they’re panels meant to be on the roof of a house I would assume they could handle any weather…
Yes those should work fine for 24/7 outdoor use. Those panels are at a very high angle though. I assume they fully tilt between 0-90 degrees off the wall correct? Are you located at a high latitude which requires you to put them at such a steep angle? If you don’t mind asking where abouts are you located? The panels need to be perpendicular to the Sun. 90 degrees essentially. The tilt can exceed no more than the Altitude of the Sun. So if the sun is at 30 degrees you cannot tilt 60 degrees to get 90. If the Sun is at 60 degrees you CAN tilt 30 to equal a perpendicular angle.
EDIT: Nevermind I see your location listed on profile. The angle of Sun is very low where you are at this time of the year which explains orientation on the wall.
@sealy1986 I’m in Johannesburg, and with regards to the tilt of the panels, at first the panels had a tilt of 25 degrees but would only get about 560watts peak sun in summer. I tilted it some more to about 35 degrees and got 650 - 700 watts. I then pushed the tilt to 55-60 degrees which gave me the maximum amount the AC200max could handle from 8:30am in the morning till about 2pm when it would gradually decrease. I was getting a constant 900 plus watts till my unit stopped charging.
Even in winter, the power was still above 750 to 850watts from morning to afternoon.
That sounds normal. You should isolate each panel by testing each one individually. If one of the two 545W panels has gone bad (even in series) it will drag the current down to whatever the failed panel is operating at. So measure panel #1 and see what the volage/amps is, and measure panel #2. Each separately. Not sure how much of a pain that would be since you have cables running down conduit. TLDR - Isolate and test each panel separately
I am in South Australia at Latitude -34.5 deg S. Jo’berg is at -26 deg South.
The ideal tilt here is 35 deg. The ideal for Jo’berg is 25 to 30 deg.
That is Tilt from horizontal not vertical. Your panels are way to high an angle. If they were flat on the ground, that is zero degrees, you then lift 30 degrees. They should also face due North. However, due north or up to 10 deg either side of N is ok.
The other thing to measure with your meter is voltage drop. Measure the array near the panels as they are wired and again at the other end of the cable run. Try to do this within say 15 minutes of each measurement and in stable weather conditions as this will vary over time anyway.
The panels on my roof are at 23 deg as that is the roof angle, not quite enough, but the roof is fixed lol.
Calculate voltage drop, by dividing the voltage at the power station by the voltage at the panels as a percentage, it should be less than 3%. If it is a lot more, you need heavier cables.
@Mandp You’re right 35degrees is the ideal position, my fault for not elaborating on my math, my panels are at 35 degrees. The reason I said 55degrees, is because when using the angle meter, my starting position was the 90degree wall, so I tilted the panel till it read 55degrees on the angle meter. So if we calculate (90° - 55°) = 35° degrees. My apologies for not elaborating, (my fault, I assumed everyone would know my starting position).
And @sealy1986 Yes, as soon as my multimeter arrives, I’ll test from the panel side all the way to the other end of the cables.
Also Quick Update: It’s 1:40pm with sun (temp 14°) , INPUT Voltage 0.0 - INPUT Power 0) It’s not charging today.
@Mandp I think I understand what you’re saying, but with regards to my set-up (if you look at the previous image that I sent)… My solar panels are fully adjustable, and can tilt further than the current angle if need be. But the reason I settled for this current angle was cause it maxed out the INPUT Power of the AC200Max which is (1KW), and the current angle has also managed to give me a constant (1KW) since last year. So unless the Solar Panels are broken, my current angle shouldn’t be a problem to an extent where I move from (1KW) to 0…
Also as mentioned in a previous reply, I tested multiple angles which started from 500watts until I managed to get to 900plus. It would make more sense if dropped from (1KW) to 600watts or 500watts, indicating that I need to re-adjust the solar panels but in my case it moved to 0…
I believe once my multimeter arrives, I’ll be able to troubleshoot some more.
You can still achieve a perpendicular angle from the Sun on a wall mount unit. The difference being you go backwards from 90 to 0, instead of ground mount where you start at 0 and go to 90.
I used https://www.suncalc.org/#/-26.1768,27.9637,10/2025.07.05/10:00/1/3 to find your angle this time of the year. From 10AM to 3PM (10:00-15:00) the altitude of Sun was between 30-40 degrees, but Here’s the problem… You cannot exceed the altitude of the Sun or your panels begin to face away from the perpendicular angle point. This means you can mount a 30 degree panel against a 60 degree sun, but not a 60 degree angle against a 30 degree sun. The angle of the Sun is low. The minute you pass 30 degree tilt you are now facing AWAY from the Sun and henceforth you will likely get 0 output. What you need to do is since you are at a vertical alignment, you need to tilt your panels 60 degrees off the wall, to equal the same “30 degree” tilt from a ground mount. This will net you an angle that is not higher than the Sun during peak solar and you should get power. TLDR - Your panels are tilted way too high. Angle them 60 degrees off the wall or a bit more.
@sealy1986@Mandp I think I’m getting confused, I’m not sure if I’m missing something but (let me explain) 4 days ago I was getting an average of 900 plus watts of solar power on (2 x 545w) panels, which have a maximum of (1090 watts) = Meaning that I was getting Maximum-Power . The next morning my unit was no longer charging, are you saying the sun shifted so dramatically in 1 night that my panels went from (1KW) to 0?
Also, how were my panels getting 900 plus, watts of power if the angle was off by that much? Wouldn’t it make more sense for the Panels to be Broken than to have such a dramatic shift, if I was getting maximum power input only 4 days ago? (one night before my issue).
The ideal time to set the angle is around mid day, when the sun is at its peak. The only exception to a semi fixed panel is one that auto tracks the sun. Otherwise you would be constantly adjusting them throughout the day.
However, if your panels are not facing due north, this can be slightly adjusted.
I have 2 x 150W solar mats, with their own fixed leg at 35 deg (from horizontal. I set them up facing north. Early morning and late afternoon, their output reduces due to the bad directional angle. But, they are at an off grid camp and pegged down so the wind doesn’t blow them over. For me to “chase” the sun is too much to do, so they are set to get the best output from their semi fixed location.
@BLUETTI_CARE@sealy1986@MandpMAJOR UPDATE: I decided to just dig up the conduit pipes, and pull the cables out… (just to check them off the troubleshoot list, couldn’t wait any longer for the multimeter) as I pulled on one end of the cables, they immediately snapped. I opened one joint of the conduits and pulled on the cables and a nest of ants swarmed out. Pulled out the cable and found burnt MC4 Connectors (which may have been due to resistance and ants which somehow got into the pipe).
Your initial suspicions were correct…
I will run new cables, when my order comes through tomorrow… and UPDATE you the end result.
Mmmmm! that’s what I call a valid reason for poor solar lol.
Might be a good time for redesign. Put the connectors into a weather proof enclosure, both ends with no joins. That may help keep the Ants out and be easier for you to inspect in the event of another problem.
In your picture your panels are at nearly 90 degrees of the wall, but the Sun is only at around 30-40 degrees. You didn’t specify if you tilt the panels at a certain degree during the day to angle them toward the sun. If I assume you tilt the panel to match the angle of the Sun, you would achieve around SIN(70) to SIN(80) which is 90% of your power. You’ll lose about 10% of that due to conversion and heat loss so 80% is about spot on with your 900 watt projection. We were just making an observation that the configuration (as pictured) is suboptimal, so if that is how you left it, that might explain the poor output. Unless I’m confused. I don’t see how there’s anyway you can get 900 watts of solar at that angle against the wall. You have to be angling them out during the day or something, you just never specified it. Clarify if the night picture showing your solar panel against the wall IS the angle you have it at during the day (or do you move them out and position them in the afternoon?)
@sealy1986 I ran new cables this morning and I’m getting (1KW) from my panels at that angle - also please note: I do NOT change the angle of my panels during the day and I haven’t changed the angle of my panels in over a year) and as mentioned in a previous reply, I did extensive testing of all angles, and for my yard and set-up this angle gave me maximum results (35degree tilt from a 90degree wall) = Full power from 8:30am till 2pm
@BLUETTI_CARE@sealy1986@Mandp(FINAL UPDATE: SUCCESS) My order was delivered this morning, new cables and MC4 connectors. I crimped new cables, plugged them in (maximum power). I have attached images so you can see how my panels look during the day. (and the AC200max Power INPUT). I was already getting full power by 8:30am (I guess I won’t be needing the multimeter).
EDIT: Also incase you were wondering, on my property the sun rises on the left of the picture and sets on the right So the sun never directly rises over and behind my panels (that’s why I’m getting full power from morning till 2pm) before it gradually decreases to 200watts by 4pm, so if I wanted full power till 5pm (or 6pm in summer) I would need to place solar panels facing the sunset on my right facing wall (that wall is on the left side of the picture) I will only do that when I upgrade to a bigger power station.
Thank You everyone, for the help… I’m truly grateful…this is an awesome community
Yeah that looks about right too in the picture. My math/measurements were wrong. The maximum tilt angle is simply 90 - whatever the highest point of the Sun is. Any more then that and you’ll be facing away from Sun. So 90-35=55 degree maximum horizontal tilt. Your panel is tilted 35 degrees from wall vertically to get the same “55 degree” equivalent. To calculate your power you take panel tilt and subtract that from altitude of Sun and the COSINE of that result (angle of incidence) is your projected power output. 55-35=20 so COS(20) is 93.6%. Granted this is when the panel is aligned with the Sun. When the Sun isn’t directly facing the panel you have to calculate misalignment which is the SIN values. So if the Sun is 15 degrees misaligned from the panel (SIN15) would result in 25% power output loss. Think for example as the Sun is rising (in the east and heading west) and is not quite lined up with the panel yet. Since you have them fixed against the wall this does not matter as much to you as someone like me who has a portable panel, so the panels are positioned optimally to be in alignment during “peak solar times” I imagine. Does your panel tilt a full 90 degrees to a flat horizontal alignment? I was looking up what the angle of the Sun was in Johannesburg in your “summer” which is around December and its practically at 90 degrees (83 degrees or so) which means you are basically going to want those panels flat during the summer.
Perpendicular angle is essentially directly overhead at 90 degrees
Since half of 90 is 45, that is the absolute maximum tilt you can get to and achieve a 50/50 balance between tilt and Sun to get a perfect perpendicular angle. Anything past 45 degree tilt means you experience a cosine effect and your angle of incidence can no longer equal zero. You will always be some degree off.
Hi @niotumi, Thank you for the update — we’re glad to hear that the issue was resolved after replacing the cable.
Your sharing means a lot to us. We rarely encounter this type of feedback, and your case has helped guide us in troubleshooting similar issues for other customers.
Thanks to everyone for your attention and input on this matter — I agree with you, this is truly a great community!
