diy solar

diy solar

Finally, the start of my 25kw Ground Mount grid-tie system

I'm on to terminating today. Why is it that the solar panels have the opposing connector? For example, I have MC4 connectors and it has a + inscribed on it for the male side, but it actually mates up to the negative side of the panel?

It just seems confusing because you're connecting to the negative side of the panel with a connector that has a + PLUS inscribed on it. You would think the panel would have the opposite connector on it and labeled appropriately with a negative so that the connector you're connecting to it with actually matches the polarity with regards to marking.

If any of that made sense. It's always possible I'm missing something, but I don't think.
 
live4soccer7 said:
I'm on to terminating today. Why is it that the solar panels have the opposing connector? For example, I have MC4 connectors and it has a + inscribed on it for the male side, but it actually mates up to the negative side of the panel?

It just seems confusing because you're connecting to the negative side of the panel with a connector that has a + PLUS inscribed on it. You would think the panel would have the opposite connector on it and labeled appropriately with a negative so that the connector you're connecting to it with actually matches the polarity with regards to marking.

If any of that made sense. It's always possible I'm missing something, but I don't think.
Click to expand...
The only thing that makes sense with PV connectors is always the source == PV panel.
the cable/junction box with the + goes to the MC3/4 connector with the +
This is the schematic I have in my box to remind me
mc3_to_mc4_connection.jpg
 
Same as connecting a bunch of flashlight batteries in series, e.g. 4 D cell flashlight, 2 AA flashlight.

The MC connectors keep everything in the correct order.
Until you decide to parallel strings.

I usually get it wrong when I connect to a box. Always check with DMM, for polarity and voltage difference.
 
Cool. Thanks both of ya. I've got her all lined up properly. I just have to crimp them now. I did a test crimp and it looked like a very good crimp. The MC4 tool I bought does not fit the Staubli (sp?) MC4 connectors I have :( I can still assemble and then tighten them later. Panels will not be connected to them yet.
 
I've finished the weekend list and still have half of the day left. Well.... One other thing did get added, but I'm counting on someone to help so we will see. It is pulling the 250MCM cable and getting it installed in all places that I can. This should be the last major thing. Well, I think I've got to put in some ground rods for the disconnect since it will be connected directly to the service meter base. That will probably be a b****.
 
Ground rods don't bother me as much. Although can be slow going if dry hard ground, maybe rocks.

I have a road trip in the near future to pick up a new (to me) cable tugger; the guy wouldn't ship it. I'll be getting a 3-phase transformer as well in the general vicinity. I'm not doing anything like 250 MCM, just 200' of 2 awg. One difficulty is multiple Tee to go through. I'll need to wrap wires around the puller's windlass (?) and pull more. Can't just pull the nylon strap. It would be easier with a helper feeding and lubing the wire.

Unless I get me one of these, too:

1662411205325.png
 
Experience really helps in wire pulling. And lube is also good, which you know from the first thing. Wire pulling and MCM size cable were a couple of reasons I knew I didn't want to be an electrician. I was doing some work at the Atlanta Aquarium and I found out the electrician I was working with had been the foreman on the original install. I chewed him out for letting them install conduit in the lids of every section of wireway on the top of the swgr. He did hang his head in shame.
 
In case anyone was curious what the setup looked like for replacing the "T-Cap". Nothing moved even the slightest while doing this. Thanks for the suggestions!

IMG_20220904_114525.jpg
 
Uh, that's a "pusher".
As I understand, it serves as a helper, taking wire off the spool, wiping it with lube, and feeding it into conduit while tugger works at other end.

This is a puller (tugger):

1662434622619.png

I plan to get crimp/cable (various length) ends for the wires, simultaneously pull 3x 2 awg plus smaller ground.
Will have to wrap wires around the capstan and pull out lengths from conduit Tee, then feed in while pulling at next Tee.
 
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You really should get a helper to feed the pull and slop on the lube. I've seen plenty of cable pulls in my career and it's always harder if the pull has to stop once going. But the end is in sight!
 
So what do you think if this ATS? Made especially for inverter to grid. 125 amp. They also make it in 4 pole. $26.95 including $11.20 shipping. DIN rail mounted. I bought it to play with. The problem with these is there aren't any timers. You could use an external sensing relay that has time delays and source acceptability parameters though.
20220906_104524531.jpg20220906_104126455.jpg
 
"125 amp" and "$26.95" in the same sentence sounds like an issue.

I got a similar but manual interlocked 63A transfer switch, but didn't like the way it buzzed at a fraction of supposedly rated current.
I replaced with interlocked square-D breakers. Didn't want to take a chance with grid fighting output of my 4x inverters.

I've seen other brands (German I think?) that could be more trustworthy. A line of DIN parts that can be ganged.
 
Hedges said:
"125 amp" and "$26.95" in the same sentence sounds like an issue.

I got a similar but manual interlocked 63A transfer switch, but didn't like the way it buzzed at a fraction of supposedly rated current.
I replaced with interlocked square-D breakers. Didn't want to take a chance with grid fighting output of my 4x inverters.

I've seen other brands (German I think?) that could be more trustworthy. A line of DIN parts that can be ganged.
Click to expand...
Yeah, buzzing should give you pause. I see a lot of stuff rated 63 amps here which seems strange. From what I see it seems generally the largest inverters installed are 5 kw.
 
@pilotdrh Thank you. I was trying to make it nice and clean. Of course, there are always things you would do differently and things you notice because you installed it an know everything about it. lol. All in all I'm happy with how it turned out. None of it matters if it doesn't generate power and that moment has not come yet, so the moment of truth will be the ultimate factor on how well it turned out.

I just put in for the building/frame inspection with the county. It should be tomorrow (WED). Fingers crossed. I don't think there will be any issues, but one never knows.
 
Don't know if it's required in your climate, but around here they require duct seal in conduit that's used outside, and especially if it goes from outside to inside. That's to stop condensation when hot moist air hits some cold piece of metal somewhere.
 
I'll probably be utilizing that before the electrical inspection on the inverters and DC disconnects at the least. Do you recall which product it is that you used? I saw in fronius' docs it mentioned permanently elastic something or other.
 
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