Newbie here doing a 20.8kW DYI install (80 sunMAX 260W panels with microinverters)

[pclausen]

Also for those conductors in the conduit don't forget to review the wire adjustment factors in 310.15(B)(3)

In my case I will have 8 current carrying conductors (4 strings with L1 and L2), 4 Neutrals and a single ground, for a grand total of 13 wires. All are going to be #10. Looking at a fill chart for 1" PVC Conduit Sch 40, I'm allowed 15 #10 wire in a 1" pipe. However, once taking 310.15(B)(3) into account, it looks like I need to reduce the count to 70%, or 10 wires. So it appears that I need to up the conduit down to the panel to 1 1/4", which allows for 27 #10 wires. 70% of that is 18 #10 wires, so I should be in good shape. Heck, I could even run the 4 individual grounds all the way down to the breaker panel if I wanted and not have a single splice in the pass through box. Do I have that right?

[Robert1234]

Very cool, and we're much at the same point. All my fasteners are up. You are ahead of me by front rail and 2 panels right now lol. I'm not DIY this time though. Once is all the fun I can handle

P.S. You are moving along pretty quick. Impressive.

[pclausen]

Thanks. If I stick with EMT, I'll definitely use those. It has been suggested I can use flexible conduit between between the End Runs and the bass through box. They make both metallic and non-metallic. That would be a whole lot easier to work with than EMT. Everything would be below the panels, so direct sunlight would not be an issue, although that stuff is UV resistant from what I read.

I did make some decent progress over the weekend. I got all my fasteners installed on the roof:



And I got the front trim panels up as well:



And I have a couple of 1" expansion gaps along the way.



Did manage to get the first 2 panels up last night after work.





Only 54 panels to go, lol.

[tyab]

For outdoors EMT all fittings must be raintight. They are available just about everywhere. These are the ones I am using:

http://www.aifittings.com/catalog/emt/emt-rain-tight-compression-connectors-with-insulated-throat/

The term "Insulated throat" means that they have a smooth nylon insert in the body end so there are no edges for the wire to scrap on. They are required for #4 wire and larger - 300.4(G) - but I'm using them on all conduit - the cost difference is minimal.

EMT is covered under NEC article 358. Main things, ream all cut ends and no threading - must use fittings 358.28, fasten within 3 ft of a junction box and support every 10 ft 358.30

[pclausen]

Thanks for the NEC references. Good reads for sure. Based on what you said about PVC on the roof and other testimonials I found, I'll do EMT instead. Everything else inside my shop is EMT, and I already have a bender, so might as well stick with that. Need to look into what water tight fittings I'll need. The end runs on my strings feature 1/2" NPT threads, so I figured something like this would work (taped of course):

[tyab]

Nice photos - my garage has looked like that all summer (ordered the stuff way too early).

Hey - I saw in your design that you are using 1/2" PVC on roof and 1" PVC down. PVC on roof gets hot and that 1/2" can really sag, make sure you are familiar with NEC article 352 and in particular 352.44. Short version, for most areas of the country, once you have an exposed outside run of PVC near/over 6' you need to think about expansion joints. Originally I was planning on PVC above ground but switched to EMT partily to avoid those expansion issues. Also for those conductors in the conduit don't forget to review the wire adjustment factors in 310.15(B)(3)

[pclausen]

Definitely keep us posted on how the IronRidge works out. My panels, microinverters and mounting hardware showed up today. Took up an entire bay in my shop!

[tyab]

Sounds like you are moving right along. So far I have no issues with the IronRidge system. For the pipe - just source it locally. IronRidge talks about the option of using mechanical tubing but I just went with standard schedule 40 pipe since it was easy to get. I should have rails up later this week so I'll get some good closeups of those parts and how I am attaching the AC combiner boxes. One thing I forgot to mention on the blog was I used some aluminum anti-oxide on the inside walls of those caps where there would be contact with the pipe but that cap looks like it already has some sort of coating on it for oxide prevention.

[pclausen]

Very cool Bruce. Yeah, that would be the way to go if you allowed peak output is limited (by the State in my case).

tyab, looks like you made some great progress over the weekend!

I spoke to J.T. at Ironridge today, he added the SunMAX panels to their online configurator and I'm working with Renvu on a quote. So 54 panels will go on the shop roof and the remaining 24 will be ground mount, split into 2 sections given my East West elevation change.

FedEx freight called this afternoon, they will be bringing my system out on Wednesday. 4 skids in all.

[tyab]

Previously I posted about IronRidge system for possibly using some of your ground - here are some photos that we did over the weekend.

http://solargroundmount.blogspot.com/

[bcroe]

Bruce, very interesting concept of wiring 2 panels in parallel with one facing East and the other West. As
the cost of panels continue to drop, I can see that more people going for that, especially if they have limited mounting options.

They say the panels only represent 1/4 of a systems cost. Obviously this method will out perform a tracker. I got tired of seeing my
equipment doing very little under the cloudy skies of northern ILL. With the extra panels the cloudy day output is way up, and with
proper orientation the sunny days have more useful hours. Here are curves I ran with 1 + 3 indicating power on a sunny day
for a pair of E-W panels. 60 degrees elevation seems to be about right: less gives too big a mid day peak; more gives a big drop mid
day. Actual results are 50% more energy than your estimates. Every situation is different; run your own simulations and see. Bruce Roe

[ButchDeal]

What Bruce is saying is that the limit is usually AC kw, so you can limit the inverters at 20kw AC but go over 20kw DC

[pclausen]

Good deal on the IronRidge. I registered at Renvu and used their design tool to create 2 12 panel arrays. Still waiting on the quote to be mailed. I guess a human is involved before it actually gets send.

I redid my PVWatts calculations, adjusting Azimuth to 206 degrees (what it actually is for the shop roof) and also tweaked some of the other parameters, did a 2nd array that would be ground mounted. So this is what I get:



And when I combine the 2 arrays and compare to my actual usage over the last 12 months, I get this:



Last winter was pretty mild here, and if I had compared to the 12 months from 2015 instead, I would have been about 2,000 kWh short. But I think this config will work. Certainly a lot better that bolting those 24 panels to the North facing roof. I think my revised design of using a ground based mount will be able to cover 100% of my needs over the long run.

While I was on the Ironridge side, I found this really cool link to the NOAA site with a tool that shows you sunrise and sunset for any time of year. So I did it for my site.

June 20th:



December 20th:



Bruce, very interesting concept of wiring 2 panels in parallel with one facing East and the other West. As the cost of panels continue to drop, I can see that more people going for that, especially if they have limited mounting options.

[foo1bar]

I checked out IronRidge and played with their configurator for a 24 panel setup. I was a little disappointed that the cost worked out to almost $2,300

If you were looking at the list price that Ironridge puts on their tool, you need to realize that actual price when buying it from Renvu or Soligent or others is going to be a LOT less.
Ex: XR1000 14' is $91 in Ironridge's Design Assistant. But you can buy it for $49-$54
Not quite half the list price.

[bcroe]

If I read correctly, your annual production is limited by the KW rating permitted by your
PoCo, and by the weather. And you might like to be able to collect more energy. I have
a similar situation. You might be able to improve the numbers with a different panel
deployment. 25164 KWH annual is 1210 KWH per KW system. I have similar issues
issues here, but generate 1800 KWH per KW.

Tracking isn't really worth the cost under good sun. Using more panels will accomplish
the same sunny output, but it will ALSO boost your cloudy output (cause cloud dispersed
light doesn't care which way the panels face). Tracking does NOTHING to boost your
output under clouds.

Just imagine 2 panels back to back, one facing east, one facing west. Connect BOTH in
parallel to the same inverter, because they will never peak at the same time. The power
rating isn't increased, but the hours of useful production are considerably lengthened. And
output under clouds is nearly doubled.

Here is one experimental version of the idea, it probably works best with string inverters.
15 KW of inverters under ILL clouds manages 27,000 KWH annual. Some curves for
different angles are under thread SUN HOURS. Bruce Roe