To summarize....
- The correctly sized MPPTs weren't available, so a smaller model was used.
- The correct wire size wasn't available, so a larger size (though still in spec) was used
- The correct ferrules were not available, so none were used
- The installation manual clearly says that fine stranded wire must be used or the terminals will overheat, but medium stranded wires were used, presumably also because of availability
Yet all the focus is on why the MPPT design doesn't accommodate all the things done wrong in the installation, with no blame on the installation shortcuts? I get that all this stuff is hard to get or do in Greece, but own it. Don't blame it all on the product.
The MPPT 100 / 15 was connected to 1 panel only and the max amps were 12 for that panel, so the MPPT controller was large enough. I wanted a 100 / 30 for the simple reason that I would have been able to add one more panel and to have everything standardized.
The panel does 12 Amps maximum and that is the exact maximum for a 4 mm2 cable. However, the short circuit amps are 12.41, meaning the amps can go over 12 Amps, therefore the 4 mm2 was not an option.
As stated, the 5 mm2 cable is non standard in the EU, the design is aimed at the American market.
The connection block itself has an opening (for the cable) of 2.8 mm. A 6 mm2 cable is 2.76 mm. There is no possibility to add a ferrule to this cable and still fit it in the available space. The total will be more than 2.8 mm and will not fit.
The problem is not with the strands on the cable, the fire did not start because of not enough strands. The fire started because the tension of the connection was lost, thereby the cable lost contact with the connection block, resistance increased, temperature increased and the MPPT controller melted and would have burned.
The connection block does not grab individual cables, it is merely a flat, smooth surface that comes up and squeezes the cable against another smoot surface. There is no contact between the screw and the individual strands. I.o.w. the amount of strands has nothing to do with the capability to hold a cable in place. Temperatures in the cables were not high prior to the fire start, i.o.w. it is not the case that the temperatures are always high and therefore the connection block failed.
In the mean time I googled for connection block failures and as it turns out, more equipment has been suffering from this same problem. The connection blocks are (apparently) meant for 1 specific cable only and anything else will cause fires.
Here is one with an inverter
community.victronenergy.com
and here is another one
and then we have this one
community.victronenergy.com
and then we have this one
The fun part is that the sales rep of Victron wrote to me that they almost never have any problems, but a quick search on google will give you quite a few fires which all have the same cause. And each time the reaction of Victron is: 'you used the wrong cable, torque setting was wrong etc.'
So many fires with the same connection blocks should be a sign something is wrong.