Solar generation in rain/cloudy conditions

denmendez65 said:
If the AC cable from the inverter to house DB is a decent size then you will be fine. I think Lupus got nailed with the 12kW inverter needing a thicker cable (10mm2 i think). Most installs use 6. I cant do more than 8kW for example unless I have the right size breaker to limit the current. Wont affect me too much as I have both essential and non essential wired into the DB. Non feeds the kitchen and the other feeds the rest of the house.

So a 30A breaker on both cables with a 12kW inverter would mean about 6.9kW per cable. Plenty for me as thats easily 3 high power applicances in the kitchen pulling power simulatenously without issues. The remaining 5kW from a 12kW goes to the rest of the house.
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Yeah that freaking cable was thick and cost like 6k by itself, still got about 5m in my garage.
 
cavedog said:
Thankfully I told my installer please I want to double my setup after a year or so. He said no problem, so he put in the 10mm cable for me to be able to do like 11 or 12kW.

I'm still slightly concerned because the one day we had proper sun I ran the pool heater for like 7 hours and and aircon and was maxing the inverter the entire day at like 5kW and felt the cable as slightly warm. Not hot just slightly warm. Would have expected it to cold because it's oversized for the current setup.
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Maybe bad crimps?
 
B-1 said:
There is quite a bit of info on cable loosening over time. It’s actually a good idea to check them annually.
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Could also be chinesium aluminium cable?

5kW @ 40V = 125A

What is the cable thickness and length at the moment @cavedog?

Warm cables = wasted energy that should rather go to heating the pool.
 
The best time to buy solar items is December and January on the used market. Powerforum is riddled with very very good deals on batteries, inverters etc.

Its as if when the bonuses come in people get the urge to upgrade their solar.
 
wingnut771 said:
Could also be chinesium aluminium cable?

5kW @ 40V = 125A

What is the cable thickness and length at the moment @cavedog?

Warm cables = wasted energy that should rather go to heating the pool.
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I have never seen 10mm^2 CCA but could be. Even that at the short distance should be able to carry plenty of current though.

I have 10mm^2 running to my 2nd DB and I think the electrician said I can put up to a 60a main switch in there as its about 15m.
 
B-1 said:
I have never seen 10mm^2 CCA but could be. Even that at the short distance should be able to carry plenty of current though.

I have 10mm^2 running to my 2nd DB and I think the electrician said I can put up to a 60a main switch in there as its about 15m.
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Is it warm at 5kW for a few hours?
 
wingnut771 said:
I suspect chinesium cable then.
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I have a 3kw geyser on that side and have run pretty big loads.

Here is a chart:

image.png.28d818206efe458a909caeaef51ca22c.png
 
My entire install is done with 16mm2 and there is no noticeable increase in temperature certainly up to 45/50 A or so.

It does at times feel "warmer" than ambient but nothing of any significance , I think we forget sometimes how much energy is actually moving around in these systems.
 
denmendez65 said:
I think he was talking AC side. So if he has 10mm2 it should be nothing to worry about on 5kW, even with AL conductors.
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Chatgpt also says it's normal. It's not hot it's just slightly warm to the touch.

It's the ac cable to and from the inverter to the db. It's about 5m max.
 
cavedog said:
Chatgpt also says it's normal. It's not hot it's just slightly warm to the touch.

It's the ac cable to and from the inverter to the db. It's about 5m max.
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Even at 60 degrees it’s perfectly fine. Open a hot tap from the geyser and try to keep hot hand in it. That’s how hot they can operate and be fine. I assume you have GP wire.

XLPE can go much higher. We use that in motor field panels. And despite the insulation and the white stuff inside of the cable you ca barely touch it.

If within the current spec. I would bother worrying.
 
denmendez65 said:
Even at 60 degrees it’s perfectly fine. Open a hot tap from the geyser and try to keep hot hand in it. That’s how hot they can operate and be fine. I assume you have GP wire.

XLPE can go much higher. We use that in motor field panels. And despite the insulation and the white stuff inside of the cable you ca barely touch it.

If within the current spec. I would bother worrying.
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Put a shunt and do a capacity test with 60c wire and 30c wire.
 
wingnut771 said:
Put a shunt and do a capacity test with 60c wire and 30c wire.
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No point really. You just derate the cable at temps over 30. There is a factor for it. If it can withstand 100A for example at 30 which if I’m not mistaken is the temp cables are given the max recommended ratings. Then at 60 for example, it may be rated for 80A.

The next worry is the insulation which degrades at higher temps. GP wire over 60 isn’t a good idea. So you go for XLPE which is more expensive and not used in residential as overkill but you can push way more current in XLPE cable than GP wire for the sam diameter.
 
denmendez65 said:
No point really. You just derate the cable at temps over 30. There is a factor for it. If it can withstand 100A for example at 30 which if I’m not mistaken is the temp cables are given the max recommended ratings. Then at 60 for example, it may be rated for 80A.

The next worry is the insulation which degrades at higher temps. GP wire over 60 isn’t a good idea. So you go for XLPE which is more expensive and not used in residential as overkill but you can push way more current in XLPE cable than GP wire for the sam diameter.
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Sorry, it was a drunk post.
 
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