Converting 50kW system from micro inverters to 8x SMA inverters

[pclausen]

I would take those 2 cracked panels out while the weather is nice, and swap them with a
convenient pair in the string that already has 2 cracked. So when trouble comes, it will only affect one string and be easily serviceable.

Good idea. I'll will definitely put that on my list.

Your 20 July readout shows line voltage of 129.18 plus 130.19, near 260VAC. Some inverter voltage
monitors are programmed for shutdown at 264, you are very close and subject to any line variations.

Yeah, check out this graph of my line voltage at the shop from today:



The main culprit, I think, is that I have 200 ft of MCM350 Al from the 50 KVA transformer on the street to my house. And then another 200 ft of MCM500 Al from the house to the shop building.

Those micro inverters do cut out quite a bit around mid day, even through I worked with Ubiquiti to update the firmware to be less sensitive, but they never could fully fix it. And that was with line voltage less than 264V. Fortunately I have a grid guard code for my SMAs, so I can then them to not cut out above 264 (currently have then set to 270 which seems sufficient).

What is your snow experience?

Snow is generally not too bad here in Central VA. When we do get it, it typically melts in a day or two. I do try to get out there and keep it off the ground mounted panels. The shop roof I leave alone. Although it does sometimes take several days to melt there since the pitch is very gentle.

[nerdralph]

Agree that drilling holes in a junction box and using grommets is certainly not ideal. I searched quite a bit back in 2019 when I did that particular ground array and never did find anything I could use to transition PV wires from strings into a junction box and or directly to conduit.

These should work for you. The M8437GBT should fit 5 RPVU #10 wires.

https://www.heyco.com/Solar_Power_Components/product.cfm?product=Solar-Liquid-Tight-Cordgrips

[pclausen]

Thanks for that link nerdralph Placed and order for a couple of those along with some 3 hole ones for some of my other arrays where the PV wires just exit 1/2" conduit now with electrical tape to "seal". Didn't even know they made these. They should work perfect for what I'm doing.

[pclausen]

I got 2 panels dismounted and on the pallet last night before sundown. Started up again this morning at 6am and the metal roof was quite slippery from the dew on it, but I managed.

After loading the first row of 5 panels onto the pallet, they started getting real heavy, especially since I had to pull them over the ridge to load them on the pallet, and with 5 panels on there, I had to start raising them higher and higher.

Fortunately I figured out that once the 1st row was gone, I could just shift the next 2 rows up one and sit loosely on the mounts after removing the inverters and associated cabling:



That worked well for the first section of 20 panels. The middle section will be trickier because I can't enter each row I'm working on from the side. So I might have to carefully rest the first panel in each center section on the section I completed.

I'm measuring DC voltage on each string in each section as I go along. I DON'T want to take it all apart again later if I'm not seeing DC at the inverter!

But right now its unbearable hot and humid being mid day. The green roof panels burns you, as do the blank frames, so I'm taking a break inside with the AC on.

[bcroe]

I have a similar problem walking on my metal house roof, new in
2021. I would not try to go up there unless the sun has completely
dried it out. Then I wear these roofing boots, cougar paws made
for the situatuion. There are no panels on the roof, but I have wires
for lightning mitigation and communication antennas to rework.

I am in the process of making a series of clamps that attach to the
ridges on the metal panels, 6061 aluminum and 18-8 stainless bolts,
just like my solar array. A piece of conducting cloth tape goes down
to avoid direct metal to metal, clamp to roof contact. I plan a safety
rail up from a designated accesspoint and along the ridge, to attach
my safety cable.

Ready to use clamps can be bought, they are quite expensive, they
are not custom to my needs, and the retainer screw probably scratches
up the metal covering. There will also be a bit of rubber path coating
attached, going up to the ridge.

These clamps will not be subject to any continuous stress for things
like holding down an antenna in a storm. Pictures another day.
Bruce Roe

[pclausen]

I hear on not walking on the roof until it is completely dry. Challenge is that by then it is hot as hell. My Dockers sandals seems to stick pretty well to the metal roof, even if wet. But yeah, I hear you. Its about a 12ft drop from the lower edge of the roof to the ground. Would probably hurt plenty.

[GoingElectric]

pclausen May I ask what you do with 50kW of power?

[pclausen]

GoingElectric My solar augments my crypto miners and the house is pretty big and I got a pool and servers and stuff like that. Also have an in-law suite in part of the basement where my mother-in-law lives and wife and 2 daughters, so yeah, I use a lot of power.

I finally got everything done yesterday afternoon. It was pretty grueling with temps in the 90s and high humidity. I had to take frequent breaks, jump in the pool and what not. After that experience, I really feel for people that install solar panels in the summer, especially in the Southern states. Back in 2016 when I initially installed the panel on the shop roof, I was in September, so much cooler temps.

nerdralph Those fittings you linked to worked out perfectly. I used a 9 wire one on the roof and it matched the 1 1/4" threads on the EMT elbow perfectly:





I tied the wires up nicely before dropping the last panel over top of it.

All 8 inverters wired with #6 L1/L2:



Wire ways ended up pretty well stuffed in some sections:



I bundled the AC wires separately from the DC wires:



All closed up:



I literally had a mountain of cables left over from removing the micro inverters:



Power output @ 9:30 am this morning:



Home Assistant Energy readout at the that same time:



I only just configured it yesterday, so I'm still tweaking.

Also still working on adding all my devices. Here are the ones I added yesterday and this is their consumption so far today (as of 9:30 am):



I have a total of 96 channels with CTs on them that I need to add and that still doesn't quite catch all the circuits I have between the 2 main 200A subpanels, the shop 200A subpanel, the server room 100A subpanel and the garage 100A subpanel.

Even with the 50 kW solar plant, my electric bill is still about $300 in the summer and higher than that in the winter.



But now that all the panels are producing all the time, and my efficiency should be better, I'm very curious to see what my next few bills are going to look like. I'm also going to wash all the shop roof panels as most of them were pretty nasty looking.

[pclausen]

Hot and hazy today with a thin layer of clouds, but I did manage to break 45 kW:



Trying to figure out how to best sell all those micro inverters and cables. I'm thinking trying to sell them in packs of 12. All tested of course, with cables and end run connectors. They will be plug and play into a 20A breaker. They still have 5 years of warranty left on them.

[GoingElectric]

GoingElectric ... and 2 daughters, so yeah, I use a lot of power.

Yeah, that would do it.
(shudder to think what bill was like before)

VERY nice work, thanks for sharing your experience!

On the micro sale, maybe a lot of ODD and EVEN, perhaps 3 and 4, people can buy a few lots to get the number they need (thought)

[pclausen]

Good idea about even and odd lots. Will definitely give that some thought.

Finally had the sun peek out today:



The shop roof inverters finally got a bit of a workout. Still can't wait for a nice clear, cloud free day, from sunrise to sunset.

[pclausen]

Finally got my Energy dashboard in Home Assistant properly configured:



Pretty slick I think.

[peakbagger]

Definitely looks slick !

[SunEagle]

I don't know if you noticed but you used 10kWh each hour for a number of hours in the morning. That amount would drain a standard Tesla battery system.

[pclausen]

Yeah I'm aware. That's basically my mining rigs and servers that run 24/7. I just put together a "Mining" dashboard a few hours ago, so it had not yet had a chance to accumulate much for kWh for the mining rigs yet, but you can see the live Watts are about 10kW:



I got the shop panels cleaned last night:



Every little bit helps, lol.