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1620w worth of panels producing a maximum of 1000w.


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I guess that’s why places like this are so important where people offer advice based on own experience without actually having any vested interest in what you buy. 

1. Correct 2. Correct Additional items, check to ensure that you have an inline fuses close to panels as well

There is a ton of information available on various platforms on the internet with regards to anything that one needs to do.    Whenever I need to do anything at home, I will always try to resea

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Just now, Chloe said:

Yip sorry I missed the parallel so it seems all your cables are incorrect.

worst part is, as i am having this conversation with the forum, im sharing all these facts with the installer, and am getting the "but these are the same cables we install on all our installations" story and basically no willingness to take responsibility for the massive oversight/screw up! 😡

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3 minutes ago, profa said:

so more or less the size of the current battery cable?

that seems excessive. I will try to find the sans regulations to see if anything is mentioned. 

The 6mm is definitely wrong as its getting warm which is an immediate sign that something is wrong. 

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1 minute ago, profa said:

worst part is, as i am having this conversation with the forum, im sharing all these facts with the installer, and am getting the "but these are the same cables we install on all our installations" story and basically no willingness to take responsibility for the massive oversight/screw up! 😡

Yes basically your solar cables should be the size of your current battery cable and the battery cable about 3 times that.

As for the installer... always the case... I've even seen guys use 1mm housewire.🤪

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4 minutes ago, profa said:

but these are the same cables we install on all our installations

probably, and probably no one really notices or its not the same system that he installs that require the panels in parallel. 

BTW, did he give you a COC. 

I once went to ACDC when i was doing my install. I wanted 10mm cable to run from 1 db to another 10m away. Salesman was trying to convince that i only need 4mm and said they even use 2.5mm at times for inverter installs. I obviously did not buy anything from him. 

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4 minutes ago, Vassen said:

that seems excessive. I will try to find the sans regulations to see if anything is mentioned. 

The 6mm is definitely wrong as its getting warm which is an immediate sign that something is wrong. 

It's not 6mm solar cable.

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3 minutes ago, Vassen said:

that's also a possibility. @profacan you maybe post a picture of the cable. 

All of the solar cables ive seen have some sort of description on them. 

He said it looks more like speaker cable but I da agree with a photo of the cables otherwise we're just speculating!

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23 minutes ago, Chloe said:

He said it looks more like speaker cable but I da agree with a photo of the cables otherwise we're just speculating!

with all due respect, i never said that. i said its about as thick as 8 gauge car audio cable which is more than adequate for a 4 channel amplifer drawing 20-40 amps at 12v. speaker cable is between 10-14 gauge. 

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8 minutes ago, profa said:

with all due respect, i never said that. i said its about as thick as 8 gauge car audio cable which is more than adequate for a 4 channel amplifer drawing 20-40 amps at 12v. speaker cable is between 10-14 gauge. 

Sorry not that clued up on car audio but its still not the right type of cable. I know some guys use battery cable. I've used some thick speaker cable as specially if you're running a few big speakers.

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53 minutes ago, Vassen said:

that's also a possibility. @profacan you maybe post a picture of the cable. 

All of the solar cables ive seen have some sort of description on them. 

pictures attached. battery cable is 25mm2 and solar panel cable definitely 6mm2 (picture i know isn't too clear, but i could make out its a 6)

IMG-20201015-WA0039.jpg

IMG-20201015-WA0040.jpg

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1 hour ago, Vassen said:

I would rather go with 2x 6mm2 cables. Probably cheaper, more common and easier to work with than 10mm2. 

actually was thinking the same thing. but i would really prefer a single cable as my OCD would bug the hell out of me with 4 cables where there should be only 2.

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58 minutes ago, profa said:

actually was thinking the same thing. but i would really prefer a single cable as my OCD would bug the hell out of me with 4 cables where there should be only 2.

2x 6mm2 cables would allow you greater flexibility in the future.  Believe me, the bug will get stuck and you will most likely upgrade your inverter in the near future.  

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1 hour ago, Bloubul7 said:

2x 6mm2 cables would allow you greater flexibility in the future.  Believe me, the bug will get stuck and you will most likely upgrade your inverter in the near future.  

I totally agree with this. You can also easily isolate part of the string if you need to. 

As I said, 6mm is more common, probably cheaper and easier to work with.... and you are getting 12mm2 instead of 10mm2

You also don’t waste the cable that you have. Use the cash towards the other missing elements in your system. 
 

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19 minutes ago, Vassen said:

I totally agree with this. You can also easily isolate part of the string if you need to. 

As I said, 6mm is more common, probably cheaper and easier to work with.... and you are getting 12mm2 instead of 10mm2

You also don’t waste the cable that you have. Use the cash towards the other missing elements in your system. 
 

according to this using 31v, 48amp, 15m length both ways (30m total) and 3% voltage drop, I need 50mm2? so even 12mm2 is hopelessly inadequate?

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1 hour ago, profa said:

according to this using 31v, 48amp, 15m length both ways (30m total) and 3% voltage drop, I need 50mm2? so even 12mm2 is hopelessly inadequate?

Well, you dont need to plan for 3% drop. Your panels are giving you 31V, and your inverter needs around 27V. So i think a higher tolerance is still fine. You are also not running the full 48A. 

This disadvantage of using lower voltage 24V systems, is that you need to cater for double the amps to get the same power as a 48V system.  

 

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10 hours ago, Vassen said:

Well, you dont need to plan for 3% drop. Your panels are giving you 31V, and your inverter needs around 27V. So i think a higher tolerance is still fine. You are also not running the full 48A. 

This disadvantage of using lower voltage 24V systems, is that you need to cater for double the amps to get the same power as a 48V system.  

 

Even when I enter, 27v, 45 and 46a (I do actually think those panels are cabable of doing 48 or very near to it perhaps 47) and 15m distance with 5% voltage drop, the tool still gives me 25mm2 cable required. So two 6mm2 is not adequate? Or what am I missing? 

Or should I think of it this way.....when I tested 3 panels on their own, I got 25v and 24amps (amps are right but volts are very low). So 6mm2 is adequate for 3 panels? If so, then another 6mm2 cable for the other 3 panels should work?

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15 hours ago, Vassen said:

probably, and probably no one really notices or its not the same system that he installs that require the panels in parallel. 

BTW, did he give you a COC. 

I once went to ACDC when i was doing my install. I wanted 10mm cable to run from 1 db to another 10m away. Salesman was trying to convince that i only need 4mm and said they even use 2.5mm at times for inverter installs. I obviously did not buy anything from him. 

I missed this sorry. No he did not. But that is not entirely his fault. I bought my house from scumbag human beings who supplied me a fake COC and then left for Australia. I even out of generosity let the wife stay in my house after it was registered, rent free for a month as her flight was only a month after registration. I only discovered the COC was a fake when I compared it to what is actually in the house and the current state of the DB when the cover was off. 

So this electrician sorted out more or less all the disasters waiting to happen regarding my electrics in the house. So the plan was for him to come and do a proper COC after everything is fixed and my solar install is in. But now, I obviously see I cannot trust him to do a proper job with regard to evaluating my COC to standard. So will have to get someone qualified to the COC including the solar install. 

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12 hours ago, profa said:

Even when I enter, 27v, 45 and 46a (I do actually think those panels are cabable of doing 48 or very near to it perhaps 47) and 15m distance with 5% voltage drop, the tool still gives me 25mm2 cable required. So two 6mm2 is not adequate? Or what am I missing? 

Or should I think of it this way.....when I tested 3 panels on their own, I got 25v and 24amps (amps are right but volts are very low). So 6mm2 is adequate for 3 panels? If so, then another 6mm2 cable for the other 3 panels should work?

Okay. After doing some research on this, it seems like the actual current carrying capacity of a conductor carrying AC and DC is the same at low frequency.  So 6mm cable can actually handle 49A. This doesn’t explain why the cable gets warm though. 

Voltage drop is going to be higher as the cable gets thinner as the resistance is more     
 

So I think adding another 6mm cable and running 3 panels off each cable should be sufficient. 

Extract from SANS attached. 

B1A30A8C-BA1E-4194-8F8C-390EA9655641.jpeg

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13 minutes ago, Vassen said:

Okay. After doing some research on this, it seems like the actual current carrying capacity of a conductor carrying AC and DC is the same at low frequency.  So 6mm cable can actually handle 49A. This doesn’t explain why the cable gets warm though. 

Voltage drop is going to be higher as the cable gets thinner as the resistance is more     
 

So I think adding another 6mm cable and running 3 panels off each cable should be sufficient. 

Extract from SANS attached. 

B1A30A8C-BA1E-4194-8F8C-390EA9655641.jpeg

Sorry but I doubt the above extract is relevant.  The above appears to be based on armoured cable in a 220v environment

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1 hour ago, Bloubul7 said:

Sorry but I doubt the above extract is relevant.  The above appears to be based on armoured cable in a 220v environment

Oops. Didn’t notice the armored cable part. 
Second column though specifies AC or DC so it’s not just 220V  

My extract of the standard does not include unarmoured cable less than 16mm. 
 

See voltex lists the 6mm Gp wire as rated for 45A. Solar cable is rubber insulated so should be the same if not better. 

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On 2020/10/15 at 11:30 PM, profa said:

the panels are happily producing between 28-30v now at about half load

Right. 28-30 V because your battery is now bulk charging, and it's reached the absorb voltage of ~28.8 V. The panels may be a little higher (perhaps half a volt) than the battery, due to voltage drop across the MOSFETs and wiring.

On 2020/10/15 at 11:30 PM, profa said:

At full load (well when I draw more than they can produce) they produce about +-28v but obviously not near the amps they should be producing (38-39 instead of 46-47). 

Under load, the battery voltage will sag a bit, hence ≈28 V rather than 28-30 V. If the panels are rated at 46-47 A, then under normal conditions you'd expect only about 80% of that (a bit more, even over 100%, under unusual conditions that don't last long). 80% x 46-47 V is 37-38 A. So your system is likely performing as it should, if the wiring is up to scratch.

8 AWG is about 8 mm², so if your PV cables look like 8 gauge, they're probably 6 mm² (double insulated, so they look thicker than normal 6 mm² cable). You need more than one pair of 6 mm² cables from the roof. You need fuses or breakers somewhere as well, either rooftop or in a combiner box. Otherwise, a panel that short circuits could have 5 others pouring all their current into it, risking fire. Panels can typically only handle about twice rated current.

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1 hour ago, Coulomb said:

Right. 28-30 V because your battery is now bulk charging, and it's reached the absorb voltage of ~28.8 V. The panels may be a little higher (perhaps half a volt) than the battery, due to voltage drop across the MOSFETs and wiring.

Under load, the battery voltage will sag a bit, hence ≈28 V rather than 28-30 V. If the panels are rated at 46-47 A, then under normal conditions you'd expect only about 80% of that (a bit more, even over 100%, under unusual conditions that don't last long). 80% x 46-47 V is 37-38 A. So your system is likely performing as it should, if the wiring is up to scratch.

8 AWG is about 8 mm², so if your PV cables look like 8 gauge, they're probably 6 mm² (double insulated, so they look thicker than normal 6 mm² cable). You need more than one pair of 6 mm² cables from the roof. You need fuses or breakers somewhere as well, either rooftop or in a combiner box. Otherwise, a panel that short circuits could have 5 others pouring all their current into it, risking fire. Panels can typically only handle about twice rated current.

Just two things, panels are rated at 8.67 amp x 6 panels = 52 amps. Three panels easily produce 24 amps. So shouldn't 6 produce at least 48 amps?

I will climb in the roof today and measure the distance of thd cable myself as that is such an important factor in my opinion. I have a fuse in my AC DB board for the solar panels and that is it. No combiner box. No protection at the panels in the roof. All "professionally" installed. 

 

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5 minutes ago, profa said:

Just two things, panels are rated at 8.67 amp x 6 panels = 52 amps. Three panels easily produce 24 amps. So shouldn't 6 produce at least 48 amps?

Fair point; I was confusing one panel's rated current x 6 with what-3-panels-already-produced times 2. Can you try the other set of 3 panels to see if they also (by themselves) produce ≈24 A? Maybe they have issues with orientation, loose connection, etc.

I would think that if the cable gets warm, that means you're losing some power in the cables, but you probably will not get that power anyway because of the voltage mismatch between the battery voltage and the ideal voltage for the panels to produce power. You either lose the power in the cable or the panels. So I don't think the wiring is a big issue, unless there is some sort of wiring fault.

Actually, there will be a small effect from the battery voltage rising: when the battery voltage is low, the panels will produce closer to Isc than Imppt. Usually Isc is a little (~6%) higher than Imppt, so higher panel voltage means slightly less panel current (but higher power, until Vmppt is reached). But I'd expect that to be a small effect (≈3%). 

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