FFJG

Quite a difference! And the cloud edge "pattern" matches what I see in some of my graphs. Anyway, it seems limiting the max PV charge current to 20A wasn't the solution to tripping at 40A after all. Yesterday the breaker tripped quite often, and it looks like the PV current is affected by the load the inverter has to deal with. On my day without tripping, the load was low to moderate, but yesterday there were a few peaks of heavy load and these correlate directly to high PV current. This is logical since my inverter is running in solar/battery mode. I got the 65A breaker yesterday, and installed it last night. So of course today started off overcast and gloomy - but it brightened up a while back, and I see there've been a few peaks of up to 50A PV current with no tripping, so it seems the problem might actually be over for now. A relief as I no longer need to babysit my inverter to save power during daylight. The 65A breaker temperature is about 29 C compared to others at about 22 C. This is "better" than the 40A breaker which was getting to 33 C. Lesson learned: It's easy to jump to conclusions about what's going on if you have no experience. Or real appreciation of what the words in the manual actually mean. Thanks again for helping to flatten the learning curve...

I'm in Grahamstown/Makhanda, known to some as Tamedogs. No smog to speak of, unless there's a brush fire in the area somewhere. It's only since having panels that I've noticed the variability in brightness, even on a seemingly clear day. The cloud edge phenomenon is something I hadn't really noticed or paid attention to, but it probably explains some of the peaks I've experienced. I need to work out a way of measuring this that doesn't depend on panels. So, even though the immediate problem seems to be sort of solved, the breaker is going to get upgraded anyway so as to give me options - in any event it's on the way. I've been fiddling quite a bit with Home Assistant and Solar Assistant, and it seems I can set the inverter max PV charge current from inside Home Assistant. Given that the load shedding schedules can be got into home assistant it should be possible to set up an automation to change the max charge up and down depending on time of day and time to load shedding in order to be nice to batteries yet allow for trying to get a full charge.

I've changed the Max PV charge current setting on my inverter to 20A (previously I had this set to 30A and 40A at various times) and so far on the hottest day we've had, there have been no trips on the 40A breaker. Looking at my graph of PV current, today it's been sitting at about 20A +/- 3A, with a few brief peaks to just over 30A, well below the breaker rating. Could this have been my problem all along? Nothing like learning from trial and error without burning anything down! If this is a solution, then clearly if I wanted to (or need to?) charge at more than 20A, it'd be wise to upgrade the breaker to 65A. But is a higher charge current desirable, or will it be bad for the batteries? Thanks again to everyone for the insights and info. A sort of related question - how does one measure whether it's a really sunny day independent of your panels? I'm just assuming that today is hotter'/sunnier than yesterday when I was tripping all the time, to the extent I left the panels disconnected until the sun went lower.

It's nice when real life obeys the laws of physics and all the theoretical bits fall into place with an equipment saving "click" at the right time. Thinking back, the current 40A breaker was chosen because the rated Isc of the panels is 9.38A, so "the system won't go above 40A". Is there some rule of thumb about what sort of fudge factor to add to this? i.e. how do they arrive at the 15A fusing recommendation for this type of panel? A further question - I'm just assuming the cabling will be OK - a set of 2 panels are connected in parallel by two "Y" connectors for the positive and negative, which is repeated for the other two panels paralleled in the same way. The two parallel sets are then linked together by a final two +/- "Y'"s which lead into the breaker. The wiring throughout is 6mm^2 panelflex. But now I'm thinking maybe the last leg from the final "Y" of each pair into the breaker should be upgraded to 10mm^2 given the temperature of the breaker being about 35 C? Also from the breaker into the inverter? I'm not clear on the rating of the solar connectors themselves?

Thanks for this - it seems then that a 63A DC breaker should be reasonably "safe" given what my panels can put out and what my panel wiring should handle. The inverter should be able to look after itself. The 125A job I pictured earlier deals with much thicker wires than those coming from the panels, so even if I was comfortable using it, it wouldn't fit! I'll order a 63A one tomorrow (I'm not in a major centre and things like this need to be got from elsewhere) and get it installed. Hopefully that resolves my problem. I'll give feedback either way. Thanks to everyone for the feedback/advice/ideas.

An attempt at finding peak current - Here are graphs of my PV current and voltage as exported to Home Assistant: You can see the voltage drops to zero are when the breaker trips...

I'm not sure how to monitor peak current on the panels? I just have a normal multimeter, nothing that'll record and store a max value.. We've had partly cloudy conditions often, but February is the first really hot and sunny month since installing my system. December and January were mostly overcast with a bit of sun every now and then. FWIW. the breaker gets warm (35 C) but not hot at the stage it starts tripping. The other breakers are about 22 C. A different, but related question: You can set the max PV charge current on the inverter, and my understanding is the inverter limits PV input to max charge current. As I understand this, it means the inverter should be able to protect itself, provided I've set up max charge current to something less than the 50A the inveter is rated for - maybe something like 30A? If I replace the breaker with a 63A DC version, it should deal with the tripping, but the inverter should be OK provided my understanding of the current limitation is correct? Or am I completely misunderstanding things here? Thanks for the previous feedback....

If my 4 panels in parallel are rated at 8.89A Imp each, why is my 40A DC breaker tripping out? Voltage never exceeds 47V. And would it be safe/OK to upgrade to a 63A DC breaker?

Thanks for that. My inverter says this: My 4 paralleled solar panels are rated at: This should mean my max voltage to the inverter will be 47V, and the max current 4 x 8.98 = 35.9A. In reality the voltage aspect is not going to exceed the max 80V of the inverter, but the current is another matter. My 40A breaker is tripping, but only just on a really sunny day, with no inverter error messages. My Solar Assistant shows that the PV current gets to about 45A. In addition, it's possible to configure the inverter with max charge currents of 20, 30, 40, 50A and it seems there is a "Limit PV to max charge current" seting in the inverter. So, to simplify the above, a 63A DC breaker, while on the high side will not cause major problems? I don't think it's easy to find a 50A breaker.... Thanks again...

All four of them are in parallel. And according to the numbers from Solar Assistant they are giving out just a bit above 40A around the time the breaker trips. I have a bigger breaker - much bigger: but while it would work, it's not obvious to me if it'd be safe to use? What ratings are available, and what amp rating should I get? Thanks...

I have a Mecer Axpert 24V 3kva inverter, connected to 4 x Mecer 330PCe solar panels in parallel. Isc on each panel is 9.38A and Voc is 47V. The isolator/breaker is a 40A DC as follows: On a really sunny day, this breaker trips frequently, around midday when the panels are pumping. There's no error on the inverter, and it carries on functioning but it no longer sees the panels. To reset, I isolate the inverter from the mains and reset the breaker, then reconnect the inverter to the mains at which point the panels are again functional. I'm running Solar Assistant which gives me some visibility and control over the otherwise fairly dumb inverter. Any ideas on what might be going on, or what inverter settings might be causing this? Thanks...

What it should be showing (from HA)

Not really gone again, but showing past load shedding schedule rather than future schedule.

In Grahamstown, using latest beta version. It seems to be fixed now, after being non-functional for a few days. The Home Assistant loadshedding integration has been working fine throughout.

Stopped working for me a few days ago. Anyone else seeing this?