Shedhenge

[nowty]

I've got SS screws into alu rails, never noticed any problems here, I think it needs to be permanently wet for a problem.

[Oldgreybeard]

I've got SS screws into alu rails, never noticed any problems here, I think it needs to be permanently wet for a problem.

TBH, I think you're right. My old yacht had stainless bolts and pop rivets holding fittings to the alloy mast and that didn't seem to ever cause any corrosion issues in the many years I owned her. I did tend to use chromate past (aka "gorilla snot") when assembling parts with dissimilar metals, but that was probably overkill.

I have noticed that our recently installed aluminium gutters are all fastened with stainless screws and black top hat washers, though, so presumably there is some concern that corrosion might be an issue with mixed metals in a location that's likely to be wet from time to time.

[spread-tee]

At long last things are happening. Bimble solar delivered the inverter and 2 of 3000c pylons plus a bunch of other stuff 3 weeks ago, and just today Mr Caesium has sold me three of his unwanted 2000 pylons (thank you again Mr C) so there is no excuse now. I have finally managed to fend off work until the second week of the new year, so the plan is to get most of the install done over the festive period.

To that end some mysterious holes have appeared in the woodstore area, the idea being to set four concrete spurs into the ground with a substantial blob of concrete on each, to which some fairly beefy unistrut type sections will be bolted. These will protrude just above the woodstore roof and in turn will support two lengths of treated 47*100mm treated timbers, on top of which will rest three panels tilted at about 35 degrees up from horizontal. Three more will live at the same orientation on the shed roof. These six will make up one string of just over 2.4kW p to be joined by another six later on, but that is chapter two.

I know in the past I have extolled the virtues of Screwpiles, and I still think they are great, but I have gone for concrete here because as I am only going to need four footings it is hard to justify the delivery and hire costs for such a small job sadly. Also I think having a sizeable mass of crete at and just below ground level will be a stiffer construction than having a 50mm tube protruding out of the ground no matter how deep it reaches down, hopefully better at resisting the dynamic wind loadings

Photos will follow for those interested.

Thanks to all

Desp

[spread-tee]

Finally getting some stuff built, 3 panels now reside atop the woodstore but of course the fitted cables are not long enough. I don't think I can get into the connection box on the back of the panels so some extension is required. Would it be best to:-

extend them with cables made up with MC4s on each end.

cut them and extend with crimps and shrink sleeve,

cut them and extend with soldered joints and shrink sleeve,

or some other method?

Some more batteries have turned up many thanks to Mr Caesium, it was good to meet up last week So now we have almost 15kWh of pylons waiting ..........

Ta

Desp

[Oldgreybeard]

My preferred cable jointing is twisting the conductors together, then soldering and then fitting two layers of the shrink sleeving that has the hot melt glue. Makes a pretty much 100% reliable joint, and is the way I joined the short cable from our submersible well pump to the long cable that comes up to the surface (although I did a belt and braces job by wrapping the whole joint with self-amalgamating tape as well).

Soldering produces the most reliable joint as long as it is not subject to vibration, I think. If it's likely to move a bit then a crimp is better. My worry is always that the cheaper crimp tools may not do a brilliant job. I remember at work that the AMP crimp tools cost and arm and a leg and even then they had to be recalibrated every year to make sure they were still giving connectors the right level of squeeze.

[AGT]

I have 9 panels to fit on my garage Q1 next year and have been thinking about the cable jointing.
Just as it would be a pain to remove panels to get to a bad connection.

I think I will run kopex with 18x 4mm standard copper stranded conductors and thru crimp them under each panel, like you i favour the heat shrink crimp for belt and braces.
I think I will just terminate the conductors in a joint box/din rail terminals

[spread-tee]

My preferred cable jointing is twisting the conductors together, then soldering and then fitting two layers of the shrink sleeving that has the hot melt glue. Makes a pretty much 100% reliable joint, and is the way I joined the short cable from our submersible well pump to the long cable that comes up to the surface (although I did a belt and braces job by wrapping the whole joint with self-amalgamating tape as well).

Soldering produces the most reliable joint as long as it is not subject to vibration, I think. If it's likely to move a bit then a crimp is better. My worry is always that the cheaper crimp tools may not do a brilliant job. I remember at work that the AMP crimp tools cost and arm and a leg and even then they had to be recalibrated every year to make sure they were still giving connectors the right level of squeeze.

We do have a proper crimp toolset, but like you I think I prefer soldering. I have been surprised many times by how loose feeling the terminal screws are on various CUs we have worked on, even ones we have installed and used the proper torque drivers on. They certainly seem a lot looser than when we have done them up.

I wonder if the thermal cycles tends to loosen things and whether crimps suffer from the same effect??

Desp

[Mr Gus]

Crimp, flood with solder, it's a solder containment device.

[nowty]

+another for solder.

[Swwils]

Crimps are stronger and more reliable when you have the proper gear.