Northeast facing panels, just how bad?

[Watts Happening]

I've got a good sized pergola I built in our back yard, it was never built with the intention of attaching solar but with the price of panels dropping so much over the last few years I'm considering redoing the roof. So this begs the question, just how bad would my solar production be with panels facing Northeast at about a 13.5 degree tilt? Certainly can't be great, but any ballpark ideas? I assume a bifacial setup could be quite beneficial on something like this. Maybe in percentage of what I would expect facing due south etc, IE 50% of ideal production or something.

Picture for reference. It's 22x20.

 

[sunshine_eggo]

Model it on PVWatts

 

[Watts Happening]

Model it on PVWatts

Pffft, here I was living life not know about that site. It claims a 5kw array would produce 7,159kwh/year with those parameters, vs 8,172 facing due south. I suppose that's a pretty reasonable amount of power regardless. Hmmmmmm!

 

[HighTechLab]

not sure if the 22ft dimension is the width or length, but still, 20~22ft span with only two 4x4 (edit: steel) supports on one side - you wouldn't find me standing on that with quite a bit more weight added by solar panels, especially on the front-left corner (as pictured).

Def. consider the structural requirements of adding the panels to it. Disclaimer: I'm no structural engineer.

 

[Watts Happening]

not sure if the 22ft dimension is the width or length, but still, 20~22ft span with only two 4x4 supports on one side - you wouldn't find me standing on that with quite a bit more weight added by solar panels, especially on the front-left corner (as pictured).

Def. consider the structural requirements of adding the panels to it. Disclaimer: I'm no structural engineer.

Totally understand, it’s all very overbuilt, those 4x4’s are 3/16ths thick and the top one with a big cantilever is 1/4”, it’s crazy strong. Additionally the cantilever is made much shorter via the 1/4” plate steel shape of Nevada acting as a gusset.

If I were to do it, I’d be removing the existing roof material which makes it a relatively low weight addition. I’ll certainly model it all though. Posts are all 4’ into the ground with 275 pounds of concrete each.

 

[Watts Happening]

not sure if the 22ft dimension is the width or length, but still, 20~22ft span with only two 4x4 (edit: steel) supports on one side - you wouldn't find me standing on that with quite a bit more weight added by solar panels, especially on the front-left corner (as pictured).

Def. consider the structural requirements of adding the panels to it. Disclaimer: I'm no structural engineer.

I've got a sincere electrical question on this one - when running wires back to the Sol-Ark, would you run a ground to "ground the array"? Or, would you consider a completely welded structure with (4) of those steel 4x4's cemented into the ground 4' to be a "ground"?

I can see the arguments both ways, if I can avoid a ~70 foot run of 6awg copper ground I'd be happy, but not at the expense of safety. I'd appreciate your input on this one if you have the time.

 

[rhino]

I've got a sincere electrical question on this one - when running wires back to the Sol-Ark, would you run a ground to "ground the array"? Or, would you consider a completely welded structure with (4) of those steel 4x4's cemented into the ground 4' to be a "ground"?

I can see the arguments both ways, if I can avoid a ~70 foot run of 6awg copper ground I'd be happy, but not at the expense of safety. I'd appreciate your input on this one if you have the time.

You must have minimum 3 wires from the array. PV+, PV-, and equipment grounding conductor.

 

[Watts Happening]

You must have minimum 3 wires from the array. PV+, PV-, and equipment grounding conductor.

That was my assumption, I was just thinking how something that is permanently inserted in the ground may act as it's own ground etc

 

[rhino]

That was my assumption, I was just thinking how something that is permanently inserted in the ground may act as it's own ground etc

"It should be noted that, per 250.4(A)(5), the Earth is not to be considered an effective ground-fault current path."

https://www.iaei.org/page/2021-01-grounding-and-bonding-solar-photovoltaic-systems

 

[Watts Happening]

"It should be noted that, per 250.4(A)(5), the Earth is not to be considered an effective ground-fault current path."

https://www.iaei.org/page/2021-01-grounding-and-bonding-solar-photovoltaic-systems

I'm reading it and trying to ensure I fully understand it's scope, I've only made it about a sentence past your quote and noted something:

"It should be noted that, per 250.4(A)(5), the Earth is not to be considered an effective ground-fault current path. Instead, fault current seeks a path back to the source from which it came by traveling from the site of the fault, through the metallic pieces of electrical equipment that are bonded together, through the main bonding jumper, and finally, through the grounded service conductor back to the transformer."

In my mind, the solar panels sitting on top of a metal structure such as this wouldn't really follow that convention as the "fault current seeking a path back to its source" wouldn't start or end with a transformer, as this is PV power and not power from the grid. Am I seeing/hearing that incorrectly?

 

[HighTechLab]

You aren't grounding the array to the earth with the third wire, you are bonding it.

 

[zanydroid]

You can’t expect the ground fault detection (which is inside the solark, way far away from your array) to work correctly if the fault is going through dirt instead of through the EGC like it’s designed to work with.

I don’t know WTF a lot of these SLDs for DIY oriented products omit EGC for the run from the array to the inverter. I don’t know if it was the 18k or SolArk I was looking at this weekend, but it only showed PV+/- from the array… is this just sloppiness or some cover your ass to make it less likely for user to accidentally ground one of the DC conductors.

 

[Watts Happening]

You aren't grounding the array to the earth with the third wire, you are bonding it.

Just off the phone with my local inspector and was rather surprised when I asked about this. His answer was that the city would want to see a new ground rod for this, they want the shortest path to ground possible. I asked about bonding and his take was that it wasn’t required since the panels aren’t producing line voltage.

How would you handle it? I’m struggling because they both seem to have valid points.

 

[DIYrich]

Pffft, here I was living life not know about that site. It claims a 5kw array would produce 7,159kwh/year with those parameters, vs 8,172 facing due south. I suppose that's a pretty reasonable amount of power regardless. Hmmmmmm!

If you are removing the roof, consider bi-facial panels.

 

[Watts Happening]

If you are removing the roof, consider bi-facial panels.

Exactly my plan! Especially with them being in a sub optimal direction. Try to harvest as much as possible!