Tesla string shenanigans or sorcery?

[OCJ]

Tesla has already proven they can run 4 qty #10 PV wires with #6 bare ground wire in a 3/4" EMT conduit (see group bundle #3).

The problem is the PV wire and the 1" conduit. I suspect there is a junction box where all the 3/4" EMT conduit comes together then transitions down into a 1" EMT conduit into your inverter. Picture please.

You currently have 1 qty #6 bare copper wire and 6 qty #10 PV wire in a 1" EMT conduit. This is perfectly fine. Fill percentage number is green. See picture 6 PV.jpg.

Since you need to add two more wires, Tesla would need to add two more #10 PV wires. 1 qty #6 bare copper wire and 8 qty #10 PV wire in a 1" EMT conduit violates fill percentage per Southwire fill percent calculator. Fill percentage number is red. See picture 8 PV.jpg

One way to fix the 1" conduit fill percentage problem is to switch from #10 PV wire to #10 THHN wire. Doing this makes the fill percentage acceptable in a 1" EMT conduit. See picture THHN.jpg

The deal is that they have to make the PV wire to THHN transition somewhere. My system has a large junction box on my roof right under my array where all PV wire is transitioned to THHN.

I have to assume there is a junction box at splice.jpg. If the installer used a junction box that is large enough where the splice is made (splice.jpg), then they can make the THHN transition there. Pulling new wire with old wire in EMT is not a good idea I am told. So in this case, I would pull out the old wire from the junction box to the inverter and pull a pull rope too. Then install new THHN #10 wire (4 qty) and one ground wire at the same time.

I'm not an installer nor an EE, so please check my work. It all depends on where the junction box is located.

Thank you, Phil, I appreciate the explanation and you running the numbers. Surprisingly, I'm following most of it I think. It seems that was the trade-off. As I've mentioned in another thread, Tesla definitely makes trade-offs and this sounds like one of them. Armed with this, I may engage with Tesla but keep my expectations low. I would imagine they would want to see a full year of production before making any changes. With my initial analysis I estimated a 613 kWh loss with the NW panels "pulling down" the SW panels, but that's not currently happening. I'll just have to keep analyzing it going into Fall/Winter to see if that holds up.

As for the roof pictures I'm trying to decide what to do with that. With the stories I hear about Tesla breaking tiles, I do want to get some pictures of the tiles after the install and I do want to get pictures of the junction boxes. I do also want to address the pigeon problem I have. And finally I want to plan on cleaning the panels.

The question is, do I get a ladder and the equipment and do that myself? I do a lot DIY for my car and house, but my wife is nervous about the heights involved.

Thanks again for your help.

[OCJ]

I thought NEM 3.0 was eminent in June 2021 and I chose to self install so I could do main panel changeout, new subpanels and solar install simultaneously. It was costing me $10 per day for electricity so timing was important for a couple of reasons.

That's the deadline I was initially shooting for too. When it got delayed the urgency level for me went down a bit. If I had to do it again I would ping them weekly to keep the ball rolling. It all worked out in the end though.

[azdave]

...And finally I want to plan on cleaning the panels.

The question is, do I get a ladder and the equipment and do that myself?

Most of us don't bother except in special circumstances. The risk of damage to the roof, gutters or yourself is not worth the small amount of savings. Paying someone to clean them will never pay off in increased efficiency either. Slips and falls from the roof cost exponentially more than what you'll gain from regular panel cleaning.

https://www.solarpaneltalk.com/forum/solar/the-pros-and-cons-of-solar-energy/435213-surface-cleaning-services

[oregon_phil]

Thank you, Phil, I appreciate the explanation and you running the numbers. Surprisingly, I'm following most of it I think. It seems that was the trade-off. As I've mentioned in another thread, Tesla definitely makes trade-offs and this sounds like one of them. Armed with this, I may engage with Tesla but keep my expectations low. I would imagine they would want to see a full year of production before making any changes. With my initial analysis I estimated a 613 kWh loss with the NW panels "pulling down" the SW panels, but that's not currently happening. I'll just have to keep analyzing it going into Fall/Winter to see if that holds up.

As for the roof pictures I'm trying to decide what to do with that. With the stories I hear about Tesla breaking tiles, I do want to get some pictures of the tiles after the install and I do want to get pictures of the junction boxes. I do also want to address the pigeon problem I have. And finally I want to plan on cleaning the panels.

The question is, do I get a ladder and the equipment and do that myself? I do a lot DIY for my car and house, but my wife is nervous about the heights involved.

Thanks again for your help.

Now that you know the tradeoff, you can make an educated decision on what to do with the wiring. At least you know what's going. In the end, it probably doesn't matter. More people hours on the roof might mean more chance of broken tiles. A roof leak is way worse than lower PV production.

As for cleaning, I used to go up on my pole barn with a full safety harness to clean my panels, but in Oregon it rains enough in the winter to clean my panels. Even with a safety harness, one fall or trip on my roof cleaning my panels could cause an injury. and I'm not getting any younger. Any PV improvements from cleaning were pretty much gone in a week. I live in farm country. Now I just let nature clean my panels.

[bcroe]

You currently have 1 qty #6 bare copper wire and 6 qty #10 PV wire in a 1" EMT conduit.

I did not know, that it was OK to run bare copper wire in EMT conduit. Bruce Roe