MPP LV6548 48v Splitphase 240V Hybrid build

[Mike.Indiana]

MPP LV6548 48v Splitphase 240V Hybrid (grid assist) build.

Just sharing my build to date. Presently its a whole house battery backup system. Next I need to install the 16 440W Bifacial ground mount panels. Considering 4 of the EG4 brightmount systems. Im in a residential area. The panels will run along my south facing 6ft privacy fence.

 

[Subdood]

Nice, looks sharp. The batteries look to be in some kind of locker type case. Are they a DIY lithium build or maybe AGM? What kind of bifacials did you get? Is the outside switch a transfer switch?

I built a ground mount over the winter for eight Canadian Solar 445W bifacials (for 3.6kW total), running one EG4 6500. It's been running off and on for a few circuits for about 5 weeks. But, last week I switched over my critical loads to a new sub panel powered by the inverter. Just passed a small milestone of 100kWh generated, not too bad for our location. No batteries are installed, but looking to add some when funds come available.

 

[Mike.Indiana]

Hi thank you for your comments. Its my first build so I'm learning as I go. The batteries are SOK 12v 206A. I have 8 configured for two 48v banks. The two inverters allow me to have split phase 240v power. 1 inverter per phase. The outside panel is a 200A cutoff which becomes my main panel feeding the inverters with grid AC. The inverters feed my original 200A breaker panel technically now a subpanel. With this hybrid design I can run of any combination of grid, sun or batteries automatically switched by the inverters. The downside is I have reduced my 200A service to 106A although with modern energy efficient electronics its plenty of capacity for me. I typically average under 20% capacity. The small transfer switch on the right side of my breaker panel is a transfer switch for my gas generator that I had a previously installed.

To finish the project I have 16 Aptos 440W bifacial panels to be ground mount along the inside of my privacy fence. I painted the inside of the fence white. The fence will serve as a reflector to the backside of the panels which should optimize power. I'm going to try the brightmount mount system - waiting on delivery.

 

[Subdood]

Thanks for the reply. Sounds like a very good design. So you have 2 x 51.2 x 206 = 21kWh? How how they been doing?

So how are you going to configure your solar array for the 250V MPPT inputs, 4 panels in series per input? Good idea about painting the fence, I had considered laying down some white gravel or sand under my panels.

I'm surprised your WatchPower app is working, I could never get mine to work, it would never connect to the internet.

Your work looks professional, do you have electrician experience? I'm an electronic technician with 30 years experience, but had to learn a lot before I felt comfortable about doing our system. This forum has been a great resource.

I spent part of the day starting on digging the trench between the ground mount and the inverter, a distance of about 45ft. I started it by running a 4 prong tiller along the path so I could just get the ground broken up and a bit easier to dig. Hope to get it dug, conduit laid and wires pulled in a few days. That ought to be the last task of this project.

Here's a few pics

1 and 8. One inch conduit in trench from service pole to inverter input. Added another 60A breaker to panel. Wire pull of two 4ga and one 8ga wires was a bear, but after a couple tries and retaping the wires finally got it done.
2. View under house showing conduit running between inverter output to sub-panel.
3. Backside view looking south towards barn. Big pine tree on left actually shades part of array in Dec and Jan despite it being 90ft away.
4. View of array from front. Used 4x4's and unistruts to mount the panels.
conduit.
5. Inverter in solar closet showing input and output conduits going down thru floor. PV wires coming in via IMO disconnect from outside window. Plan on mounting switch on wall below inverter and running PV wires thru wall from outside.
6. Sub-panel fed by house panel via flex conduit.
7. Sub-panel showing circuits moved over, lower two right spaces showing double pole 60A breaker that feeds inverter output to panel. Have since added another 15A breaker to these three 15A and two 20A breakers. Plan on adding maybe two more 20A breakers.

 

[Mike.Indiana]

Hi sorry for the late reply.

Yes I have 21Kwh capacity from my two inverters. Its more than enough for my home. Im typically loading at about 10% except when the electric dryer runs Im at 30%. Will reevaluate with the AC this summer. Yes I will have 4 panels in series per pv input. That should give me 199.6v per input @ 44c. I could have gone 5 panels but I would be right on the 250v max voltage per input possibly over in the winter. From what I read that 250v max input is critical for the inverters.

I had to fiddle with watch power. I couldnt do the setup on my android phone but I could do the setup on my samsung android tablet. my phone runs linage so i wasnt surprised. But once I got it setup I can access it on my phone. one thing I noticed on the setup my tablet would change inverters wifi modules in the middle of the setup. I had to double check each step that my tablet is connected to the right inverter im trying to setup. The only problem I have now is the status for each inverter is often yellow instead green and I cant find any recent alarms to indicate why that is. Initially I had a couple of EEPROM alarms but they cleared eventually. Im wondering if there is an eeprom software issue but haven't taken the time to further investigate.

Im a retired electrical/manufacturing engineer from GM. Certainly my experience was helpful but like you I had to learn a lot for this project. Its quite an investment in time and money.

My conduit was about 60'. I ended up renting a trencher. Not a trivial expense I think it was nearly $400 but to get to the 36" frostline I needed it. I ran 2 1/2" conduit for the 8 8GA PV wires.

How did your trenching go? Everything up and running.

I like your home made panel mounts. Im really struggling with that part of my project. I was going to do something similar but I have limited space and im on a bit of a grade 2 1/2' over the 60' length of the panels. I have to squeeze them between my septic system and my privacy fence and I would like to keep the height under 8' to keep the neighbors happy. Also I wanted a tiltable design for maximum efficiency and i dont want any supports directly shadowing the backside effectively shorting out the bifacial side. I bought 4 sets of the brightmounts there relatively cheap well made aluminum and adjustable. The problem is they require 16 concrete piers at 36" deep for my frostline and 16" above ground and I have to stagger them for the grade. Its a crazy amount of concrete and labor. Also the design is not compatable with bifacial due to the two horizontal supports that effectively cut the panels into thirds which I beleive will render the bifacial side useless. I found one company so far that makes the perfect mounts for me there called opsun. There commercial quality designed for bifiacial panels, fully adjustable and only require 4 ground attachment points but the cost is $7k including shipping for the hardware! Im still looking..

 

[Subdood]

Yes I have 21Kwh capacity from my two inverters.

You mean your batteries?

I had to fiddle with watch power.

There is another app you could try, it's called Smart ESS. It shows more than the WP app, and I noticed today that it was updated. I think it's a good improvement, especially considering it's free. If you do load up the app, you use the same user name and password as WP. I loaded it on my phone and Samsung tablet with no problems. I get the various alerts like you mentioned, but I don't worry too much about them. I usually get PV loss alarms, but that happens at the times of the day where PV fades in and out during twilight.

How did your trenching go? Everything up and running.

I actually got the PV and ground wires pulled thru the conduit last week. It was about a 60ft pull thru half inch pipe, at first we only got it about half way through before it got stuck. Trying to pull three 10awg solid wires thru that pipe was a challenge, so I ended up taping the wires together every foot or so and fed them into the conduit. I eventually got it thru. I buttoned it up on Thursday and got it back online later that day. Got the trench filled in Saturday and I've been cleaning things up inside and outside.

Sorry to hear that you're having issues getting a ground mount system set up. I buried my posts about 20in, as our freeze line isn't as deep. My ground mount took most of the winter to build, but got it slowly done. It was a lot of work, but I'm happy with how it turned out. If I do another array, it probably won't be as elaborate as this one. But, for now, my next task is to get a battery..

 

[Mike.Indiana]

I have 8 batteries. they are the SOK 12v 206A units. So two 48V 206A packs in parallel. No issues with them. If the grid fails they kick on instantly and will run my house up to 24hrs. I dont even notice when my power goes out unless the batteries were to completely discharge of course.

Thanks for the smart ESS idea. I will check it out.

Are your panels bifacial? If so any idea how much power your getting from the backside?

Any idea on what the cost of materials came to on your ground mount setup?

 

[Mike.Indiana]

Hey I was looking more closely at your ground mount. Did you use actual unistrut or the generic stuff like you get at lowes? what did you use for the strut end to end splice? What clamps did you use to attach the panel?

 

[Subdood]

Are your panels bifacial? If so any idea how much power your getting from the backside?

Yes, I have eight Canadian Solar 445W bifacials. No, I don't know what kind of power I'm getting from the backside. I'm guessing before the sun gets above the plane of the front panels, the back cells are producing something. That's because the sun is now coming up north of due east, and I'm getting some power early in the morning, i.e. 6-8am judging by the PV data I'm seeing from the ESS app.

Right now there's grass underneath the array, so the reflectivity probably isn't very good. I was planning on using some weed barrier underneath and then white gravel on top of that.

Any idea on what the cost of materials came to on your ground mount setup?

I think I answered this to someone else on here, but rough estimate was about $800 total. I got just about all my materials from Lowe's, like the quikrete, lumber, rails and most of the hardware. I'm not including the wire and conduit I used for the PV and ground wiring.

Did you use actual unistrut or the generic stuff like you get at lowes?

They are the Lowe's version of unistrut/superstrut, I think they're called Adamax, they're 1 15/16" wide and 10ft long. I used six of them. They cost $40 each, I think Home Depot sell a similar type strut for $35.

what did you use for the strut end to end splice?

They were thick metal plates, I placed them on the open part of the ends of the struts, and used four 3in long, 1/2in thick galvanized bolts, washers and lockwashers to fasten them. The plates are about 7in long, 2in across, and maybe 1/4-3/8" thick. Very sturdy, it's not going anywhere.

What clamps did you use to attach the panel?

To attach the panels, I used 5/16” thick, 1inch long stainless steel bolts and lockwashers, and zinc plated strut nuts that grab onto the inside edge of the struts. Probably not galvanically (rust) a good idea, but I couldn't find anything else.

I'll try to post some links of the specific materials I used when I get a chance. I'll also try to give a list of the specific materials I used.

 

[Subdood]

Here's a pic of the strut splint plate I used, the top cap that I used to attach the support 4x4 to the front post, and the hardware I used to fasten the panels to the struts; this hardware I got off of eBay.

Other than the SS hardware to attach the panels, all the hardware is galvanized steel, costs a bit more, but should last longer.

 

[Subdood]

The rough estimate for the ground mount is about $800. That includes the (6) 10ft unistruts, (3) 2ft ministruts; lumber, which includes (10) 4x4x8's, (4) 4x4x6's, (2) 2x4x10's; (2) 2x4x8's; (20) 50lb bags of quikrete, (3) 40lb bags of gravel, (4) unistrut splice plates, about 30ft of bare 6awg wire for grounding, some clamps to attach it to the panel frames and rails, and LOTS of hardware. I'm probably forgetting everything, but this is close enough. It is very sturdy, we've had several 60+mph wind storms and it was rock solid.

 

[Mike.Indiana]

Thank you for all the detailed information. This forum is really helpful. I think I'm going to build something similar to yours. I was making it too complicated. Its cheaper and easier to add more panels than pay for an elaborate adjustable racking system to squeeze out a marginal amount of extra power.

 

[Subdood]

Thank you for all the detailed information. This forum is really helpful. I think I'm going to build something similar to yours. I was making it too complicated. Its cheaper and easier to add more panels than pay for an elaborate adjustable racking system to squeeze out a marginal amount of extra power.

You're welcome. Keep in mind my ground mount is about 28ft long, and holds up 8 panels. I understand you have 16 panels? So your ground mount would have to be obviously bigger.

An added note about my post holes. For the back support posts, the holes were 20-22in deep, about 10in in diameter. I put about 1-2in of gravel in the bottom of the holes to assist with drainage, and to keep the posts from contacting the dirt.

To prevent water from collecting at the base of the posts, I cut Sonotubes in smaller sections at an angle and placed them at the top of the holes while I poured in the concrete. I then filled in this section of tube, and troweled the concrete to match the angle of the tube. Any rain runs off the side and doesn't stay at the base of the post. I also used Thompson's water seal to treat the posts. See attached pics.

 

[Mike.Indiana]

Good ideas. I do the same things sealing the posts using gravel for drainage but I hadn't thought about the sontubes.

 

[Subdood]

I also screwed 3in wood screws into two sides of the post below ground level to give them a bit more stability and to give the concrete something extra to grab on to. I didn't do that with the front posts as they were shorter.

To give the proper credit, I actually got all these ideas from someone on YouTube, altho I didn't run the Sonotubes all the way down into the holes, I just cut off about a foot tall sections at an angle, and set them in the hole with the concrete about an inch below the surface. Then I filled those up and troweled them even with the edge of the tube.

 

[Mike.Indiana]

Hi. I finally got 8 panels racked and working. I chose 4x6 posts sandwiched by 2x10's with horizontal struts. I plan to duplicate the rack for the next 8 panels. How is your system performing? by the way whats your name?

 

[42OhmsPA]

That looks great.
I'm torn between the 4x4s as support for the top rails or the 2x sandwich.
I'm currently leaning towards the posts in top.
The attached may be useful to others, I threw it together today for my crude plans to mount 12 panels at a 45 degree angle.

 

[Subdood]

Hi. I finally got 8 panels racked and working. I chose 4x6 posts sandwiched by 2x10's with horizontal struts. I plan to duplicate the rack for the next 8 panels. How is your system performing? by the way whats your name?

Hey Mike (my name's Bob BTW), looks good to me, very sturdy and good idea with the gravel. How deep did you anchor your 4x6's? What kind of output are you getting from this array?

My system's doing well, thanks. It's generated about 350kWh since it went online back in late March, average production is about 3kWh/day. We actually had a power outage early Sun morning, a local storm knocked out power to a few hundred customers. Since we don't have a battery, we had to use our Ecoflow generator to run a few things like my wife's cpap and a fan. But power came back on in about 3 hours.

Dropped a not so subtle hint to my wife like, "well if we had a battery, we wouldn't have to be stumbling around with a spotlight hooking up the generator".. she wasn't biting.