My DIY 60 kW 220 panel setup

[kundip]

Re panels facing East & West.
My brother and niece live 1 km apart. His roof faces north and she can only put panels east and west. July's production for Jim's was 688KW and my nieces was 390KW. Both systems are exactly the same spec and age - other than the way the panel's face. The percentage difference is enormous.
June July are our worst months. Both systems were installed this year.

One thing for certain there's nothing easy in solar.
It's really hard work, considering all the ins & outs, trying to save electricity costs.

 

[Evil1]

2kw PV on ur tracking mount would be a cool project, there is some good info to be found on YouTube for different tracking setups, with the space u have you could have a larger array on a rear pivot & rail or concrete track for the front guide wheels/rollers. Im sure there is a lot of simple & cheap electronics easily found nowadays to make sun tracking a simple task. Love ur obsession mate, keep it up. Cheers from Australia

 

[Evil1]

You made some good points about the micro inverter cons too, i had wondered how reliable they are given where they are generally placed, so it would make sense for you (or anyone using them) to use them on a ground mounted system or where you have better access for maintenance & repairs. Cheers

 

[stienman]

I have 3.6kw facing east/west (1.8kw each direction, out of a total 7kw system) and while there is a cost in overall efficiency, it does help spread the power out over the day so I have reduced reliance on the grid and storage (batteries). I suspect that many would benefit from such a setup given the cost of batteries and the elimination of net metering most are facing.

I'd suggest adding trees or bushes behind the array closest to the house for visual purposes. As nice as the arrays are, the view would be improved if they didn't take up so much of it.

I long ago decided not to have panels on my roof, but I'm on 4+ acres. I think you're in a similar situation. The pain and additional cost of roof solar just isn't worth it when a ground mount array is so cheap and easy. Plus, clearing them of snow is so much easier if you get the inclination to do so.

I recall seeing your mining setup on a youtuber's channel some time ago - can't recall if it was voskcoin or another, but I enjoyed seeing what you've accomplished, and am really happy to see the details behind the solar, which were largely glossed over in the mining video.

I'm scratching my head, though - with the frequency and length of your outages I'm surprised you haven't added battery storage before now. Given your mining consumption I can see that 30kwh of battery isn't going to last more than an hour or two in the dark, but aside from that your proposed EG 6500 setup doesn't appear to be fully operable in the sunlight - do you have provision to tell the non EG6500 inverters to do zero export so they can continue to work when the power is out, with the EG6500s providing the micro grid, or do you have some other method to make the full array work in power out situations?

 

[Evil1]

My thoughts. Unless up oubhave limited space. If you want to put in tracking systems it is cheaper to put in more panels. If you want to pay someone to wash the panels it is cheaper to put up more panels. If you want to put in optimizers it is cheaper to put in more panels. I could go on.
I figure any fiddling with existing, working, systems will cause breakeages or damage to roof etc.
I use Micro Inverters but I put the Inverters in an accessible place where I can change out inverters on the ground. They are Enphase & Sunny Boy ...so far none have failed.
This won the prize on hackaday 2023 https://hackaday.com/blog/?s=Solar+track Maybe you could make a hybrid of that. Snapshot of some old Sunny Boys I am adding to my system attached.

@kundip That's a very interesting setup he has with those 4 inverters wired in parallel like that. So if I was to apply what he did, basically wire the solar panels and inverters in parallel, thus allowing the inverters to be located remotely from the panels. I guess the downside to that is voltage loss. 36 VDC will a much greater loss over, say 100ft, compared to 250 VAC.

Now if you could wire the panels in series and do the same with the micro inverters, that would eliminate the greater loss, but I'm 99% sure that would not end well since the MPPT circuit would likely get really confused and unless the 4 inverters that the exact same resistance all the time, some inverters would see much higher voltage than the others and probably cause some sort of cascading failure that would fry everything.

Micro inverters on each panel are only really good where there is a higher incidence of shading aren’t they? For ur large arrays wouldn’t u be better to have 1 or 2 large HV MPPT inverters in series for maximum allowable VOC at each array site and send the AC back to main panel, DC has much greater losses over distance than AC. 3 phase inverters would have to be a good consideration also for these larger arrays, more efficient, higher volage, thinner wire runs, more power Production.

 

[Evil1]

Re panels facing East & West.
My brother and niece live 1 km apart. His roof faces north and she can only put panels east and west. July's production for Jim's was 688KW and my nieces was 390KW. Both systems are exactly the same spec and age - other than the way the panel's face. The percentage difference is enormous.
June July are our worst months. Both systems were installed this year.

Wow, that is a big difference

 

[crazydane]

Re panels facing East & West.
My brother and niece live 1 km apart. His roof faces north and she can only put panels east and west. July's production for Jim's was 688KW and my nieces was 390KW. Both systems are exactly the same spec and age - other than the way the panel's face. The percentage difference is enormous.
June July are our worst months. Both systems were installed this year.

I find that very surprising. I can see how North facing panels do ok in the summer months, but would be terrible in the winter month where they may not even get any direct sunlight, depending on the pitch of the roof they are on. But I would have thought East and West panels would produce way more than North facing panels, when looking at a whole year's worth of production.

I know for my South facing panels, I see a significant change based on season:





I'd be very curious to see what similar graphs looks like for someone with panels facing only East and West.

 

[crazydane]

Micro inverters on each panel are only really good where there is a higher incidence of shading aren’t they? For ur large arrays wouldn’t u be better to have 1 or 2 large HV MPPT inverters in series for maximum allowable VOC at each array site and send the AC back to main panel, DC has much greater losses over distance than AC. 3 phase inverters would have to be a good consideration also for these larger arrays, more efficient, higher volage, thinner wire runs, more power Production.

I wish I had 3 phase power on my street, but my little side road is just 14.4K single phase on the pole. I would have loved to have been able to just buy a single honking 60 kW inverter! I did not know that DC had a greater loss over distance than AC, for a given gauge wire.

The only reason I'm looking at East and West facing panels if I add more, is that the peak would occur earlier and later in the day compared to all my south facing arrays. My transformer on the street is only rated for 50 KVA, and I would have to melt it. If I took all my miners offline, I would be pushing 55 KVA through it (assuming a power factor of 1). I'm technically not supposed to have more than 20 kW in a residential system where I live, so I don't want to rock the boat.

Another issue with having 55 kW of power coming in all at the same time, is that I see quite a bit of voltage rise around noon, and my POCO likes to run it hot to begin with, around 246:



Zooming on on 9/1:



I had to get a grid guard code for my SMA inverters are raise the "floor" from 120 to 128 to keep them from cutting out at high noon. I don't know that I would want to go much past 260 VAC.

 

[Shimmy]

Awesome system! Did you use Ubiquiti equipment before? Given how they stick with some things I was really surprised they started SunMax. Looks like they are as reliable as my PTZ Protect camera.

 

[crazydane]

Yeah, I started out with 80 SunMax micro inverters, then talked Ubiquiti into sending me 56 spares for free to have on hand given my high failure rates. I ended using 48 of them on 2 new 24 panel arrays, leaving me 8 spares to swap out as needed and RMA'ing those as they were died.

I finally got fed up with having to swap out failed inverters and got rid of all of them last month and went 100% string inverters.

In their defense, I had issues with the inverters cutting out back in the fall of 2016 when I initially deployed them and worked directly with their design/engineering team overseas to tweak the firmware for the US market. They send me about $20k worth of test equipment to capture the waveforms coming off the grid to troubleshoot the issues I was experiencing. After about 3 iterations of firmware, the cutting out issues was all but eliminated.

The main flaw with their inverters was that during the manufacturing process, some of the surface caps were under too much tension during the ware soldering step, and caused them to separate, resulting in this:



So back on the topic of adding some East and West facing panels. I was thinking about the voltage loss of AC vs. DC, and I found this that seems to favor DC or AC for transmission:

1. Skin effect experienced with AC. There is no skin effect with DC.
   
   
   
2. Higher voltage allowed with DC for the same transmission lines. The lines have to withstand the peak voltage. With AC, that is 1.4 times higher than the RMS. With DC, the RMS and peak voltages are the same. However, the power transmitted is the current times the RMS, not peak, voltage.
   
   
   
3. No radiation loss with DC. Long transmission lines act as antennas and do radiate some power. That can only happen with AC.
   
   
   
4. No induction losses. The changing magnetic field around a wire carrying AC current causes induced voltage and current in nearby conductors. In effect, the transmission line is the primary of a transformer, and conductors near it are secondaries. With DC current, the magnetic field doesn't change and therefore doesn't transfer power.

And then I thought about the fact that I'm only using 2 of the 3 MPPT inputs on all but 1 of my SMA inverters, So I have 7 unused MPPT inputs that I could use for East and West facing panels. Here's my array layout and MPPT inputs used:



The Sunny Boy 7.0's on the shop roof are barely "oversubscribed" with a max of 7.15 kW currently. Ditto on ground array #1 with 6.13 kW on a Sunny Boy 6.0, so those 3 MPPT spare inputs would probably be the first ones I'd use if I went that route.

In hindsight, I guess I should have just gotten all 7.7s, lol.

 

[crazydane]

I recall seeing your mining setup on a youtuber's channel some time ago - can't recall if it was voskcoin or another, but I enjoyed seeing what you've accomplished, and am really happy to see the details behind the solar, which were largely glossed over in the mining video.

I'm scratching my head, though - with the frequency and length of your outages I'm surprised you haven't added battery storage before now. Given your mining consumption I can see that 30kwh of battery isn't going to last more than an hour or two in the dark, but aside from that your proposed EG 6500 setup doesn't appear to be fully operable in the sunlight - do you have provision to tell the non EG6500 inverters to do zero export so they can continue to work when the power is out, with the EG6500s providing the micro grid, or do you have some other method to make the full array work in power out situations?

Yep, voskcoin came out a couple of times shooting videos for his channel. The 2nd one went into a bit more detail about the solar.

AFAIK, my 8 Sunny Boy inverters can't operate at 100% without grid power. They do all have a 2000 watt 120V emergency power output however, that do function during a grid failure, but since the inverters are all located in the my shop building 200' away from the house, I never bothered connecting anything to them or researched if it is possible to connect the emergency outputs from several Sunny Boys together for 240V and or higher wattage.

I'm not sure why the 6500EGs wouldn't be fully operationable in the sunlight. The AC input would be connected to the load side of the 400A transfer switch and the AC output would be connected to the dual 200A sub-panels for all my house circuits. There would then be solar panels connected directly to the MPPT inputs of the 6500s and then of course the battery bank would be connected as well.

So during the day, the house would run on batteries that would be charged by the sun and at night the house would continue to run on batteries that would maintain charge from the grid power coming in via the AC input.

So this way, the 100 kWh consumed daily by the house, would be mostly supplied by the batteries / solar panels connected to the 6500s, and only supplemented by the grid when needed.

As I mentioned previously, during the winter I bring the miners up into the house to provide the heat I need, so I'm thinking that when/if I install the 6500s, I would add another sub-panel at the house, that should be feed directly from the grid and not from the load side of the 6500s. That way I can balance the miner load at the house, and only only connect the number of miners to the load side of the 6500s, that they can reasonably handle. The rest would be connected to the sub-panel connected directly to the grid.

Additionally, during an extended power outage, my diesel generator can kick in when the batteries start getting load, and that would all be automatic since the transfer switch is automatic. If the 6500 doesn't support a generator contact closure when the batteries get below a certain threshold, I'm sure I can use Solar Assistant or Home Assistant to do it for me.

 

[crazydane]

So here's a copy of my latest electric bill:



Imagine what it would have been without any solar! September of last year is when I started expanding my mining operation again and the days of double digit monthly kWh bills was over.

So my total kWh from Sep 2021 through Aug 2022 was 37,877 kWh, for a monthly average of 3,156 kWh.

So I got a good bit to go before I'll be able to eliminate my power bill completely. I added mining rigs during the fall of last year and into spring this year. But I also added 15 more panels and converted to all inverters, so that might be close to a wash as far as the consumption vs. production ratio.

Got an email into santansolar to see how much a pallet or two of his used Jinko 310W 72 cell poly panels would cost to shop from GA to VA. He has them listed for $96.00 each, which is $0.31 per watt, which seems like a decent deal. If he can put 32 on a pallet and I got 2 pallets, that would be just shy of 20 kW for a bit over $6k. I think that would get me close to closing the gap on my electric bill.

 

[stienman]

It's the hotdog/bun problem. When you have more solar, you're going to get more rigs, and then start all over again. ?

 

[Hedges]

I don't think EG inverters support AC coupling.
How about using a battery inverter that does (preferably Sunny Island), so it can interact with your GT PV Sunny Boys?
For a split-phase system that backfeeds grid, the max system is 4x SI with 24kW of SB. Once disconnected from grid, more SB could be switched onto it for total of 48kW.

 

[Browse]

As for the wife and the views from the house, you can plant some 6 FT Leyland Cypress trees to grow into a privacy wall over the next 5 years. Plant a line of them just before the first ground mount array from the house. The Leyland I planted about 5 years ago is already 25 ft tall and about 10 ft wide.

 

[crazydane]

I don't think EG inverters support AC coupling.
How about using a battery inverter that does (preferably Sunny Island), so it can interact with your GT PV Sunny Boys?
For a split-phase system that backfeeds grid, the max system is 4x SI with 24kW of SB. Once disconnected from grid, more SB could be switched onto it for total of 48kW.

Maybe I'm not interpreting this diagram correctly then:



I would have the grid connected to the Utility input (fed from the transfer switch load side) and my house feeder to the Load output. I know that if I have solar panels connected to the MPPT inputs, those will only charge the battery and NOT feed anything back into the grid. I'm not looking for that since my Sunny Boy inverters are already feeding into the grid and maxing out what the 50 KVA transformer on the street is capable of.

I think what I'm not clear on, is exactly how the EG inverters operate over a typical 24 hour period with utility/grid present on the AC input at all times along with a more or less constant load on the AC output side. Will it just keep the batteries topped off at all times and in the event that I lose grid power, start supplying the load from the batteries? In essence function just like a giant UPS? And if it happens to be daytime, the MPPT inputs will attempt to keep the batteries charged, or at least slow down them being drained.

These are the SMA inverters I have:

Discover the Sunny Boy 3.0-US - 7.7-US | SMA America

Discover the Sunny Boy inverter 3.0-US - 7.7-US ► PV performance optimization with SMA ShadeFix ► SMA's SunSpec certified shutdown device

www.sma-america.com

Are you suggesting they can somehow interact with these:

Discover the Sunny Island 4548-US / 6048-US! | SMA America

The efficient island manager Sunny Island 4548-US / 6048-US ► Now with 20 % more power! ► Efficient, simple, flexible and durable! ► Check out now!

www.sma-america.com

 

[crazydane]

It's the hotdog/bun problem. When you have more solar, you're going to get more rigs, and then start all over again. ?

Lol, yeah. That was my plan last fall, but profits kept going up, so I kept getting more rigs. But THIS time, there is going to be a lull of a few years, right?

 

[stienman]

Just as soon as everyone is convinced the crypto market has settled down, it'll shake its tail feathers and everyone will be right back at it, kicking themselves for whatever choice they made now. There does seem to be a pretty consistent 2 year lull after every big spike, but who knows.

“The stock [crypto] market is a device for transferring money from the impatient to the patient.” Warren Buffett, paraphrased.

 

[crazydane]

Ha, I love that quote! That is so true. I've been in it since early 2017 and caught 2 waves so far and HODL'ing as much as I could and just kept mining throughout it all.

 

[Hedges]

These are the SMA inverters I have:

Discover the Sunny Boy 3.0-US - 7.7-US | SMA America

Discover the Sunny Boy inverter 3.0-US - 7.7-US ► PV performance optimization with SMA ShadeFix ► SMA's SunSpec certified shutdown device

www.sma-america.com

Are you suggesting they can somehow interact with these:

Discover the Sunny Island 4548-US / 6048-US! | SMA America

The efficient island manager Sunny Island 4548-US / 6048-US ► Now with 20 % more power! ► Efficient, simple, flexible and durable! ► Check out now!

www.sma-america.com

I'm not particularly familiar with how each of the MPP and other such inverters function. Maybe some will feed grid, if UL-1741.

Yes, a system built from Sunny Islands will control Sunny Boys. That's what I have.
There are limits on current that can pass through their relays (56A per Sunny Island), which limits how much Sunny Boy wattage can be downstream if backfeeding grid. When disconnected from grid, SB wattage can be up to 2x SI wattage.

Sunny Island is expensive but there may still be some stock left over from DC solar debacle at resellers. Best deals I've seen recently were from Stella Volta, bundled with Midnight Solar boxes. Two pairs in stock:

MidNite Solar MNSI6048D-ACCPL Pre-Wired AC Couple System

Shop now for MidNite Solar MNSI6048D-ACCPL Pre-Wired AC Couple System.

www.stellavolta.com

 

[crazydane]

Downloaded the manual and looked at the diagram and the connectors. So the SI doesn't actually have any MPPT input but is designed to work in a system that also contains SBs. So from looking at this diagram:



I currently have each of my 8 SBs individually connected to an Ethernet switch on my LAN. From the diagram above, it looks like I would need to get a Sunny WebBox and have the SBs and SIs communicate over the proprietary SMA com bus, is that correct?

Looking at the specs, I see the 56A max AC input rating you mentioned:


The total current output from my 8 SBs is:



So 4 SIs will almost be enough (57.35A per SI), but I think it will be close enough since not all the arrays are at the same azimuth and tilt, so it is unlikely that all 8 SBs will peak at the same time. Of course if I start adding East and West facing panels to the 7 unused MPPTs, that could change.

So instead of this:



I could relocate the generator, transfer switch and disconnect from the house down to the shop and eliminate the drone of the generator at the house when I loose the grid. Of course the generator might not even have to kick on if the outage is that too extended as I could run off the batteries connected to the SIs. I could then also transfer my 400A service from the house down to the shop. That would eliminate the voltage drop I'm currently experiencing by having all the solar generated power spanning the 200' between the shop building and the house before it hits the meter base, which determines how much power is send back to the grid for my kWh bank.

So the diagram would look something like this instead:



The big risk is that the POCO could bust me for being way over the 20 kW of PV that they allow. But it would all depend on who they send out to approve the application for moving the service.

I could start by ordering 400A service to the shop building, and once that was up and running, call to cancel the service at the house. That would probably be less risky. Worst case, I guess I could just tell them to shove it and go 100% off grid.

Hmm, lots of stuff to think about before making a move...

 

[stevensrd1]

Good job, the first step is admitting you have a problem.

Seriously though, wow... great stuff..... can't wait to see more!

Nice!

 

[Hedges]

Sunny Island does not have MPPT or PV input built in. It is primarily used to create an island grid, AC coupled to GT PV inverters, and with AC input from generator or utility grid. It will either let GT PV backfeed through its relay (no control on how much), or disconnect relay in the case of generator or zero-backfeed to grid.

It does (or did) support DC coupled SCC. You can connect any DC charging source, with a battery shunt to tell SI how much current. In that case SI has no control over the DC charging parameters. What it may or may not still support (with latest firmware) is communication by RJ-45 cable to a charge controller. "Sunny Island Charger" branded SMA and manufactured by MSTE was supported, and Midnight Classic could connect through a data interface. In that case, charge voltage was controlled by SI, and measurement was also communicated over RJ-45.

You do not need any external monitoring of Sunny Boy or anything else to make the system work. That would be optional if you want to log production, monitor from the web, or have SMA notify you in case of failure. If you want to throttle SB output to achieve zero or limited export to utility grid (not just zero export through SI relay), some external measurement and control hardware can command SB to achieve that.

SI doesn't support communication with the newer -40 and -41 model SB. Monitoring systems can obtain data from all of them. The only interaction SI would have with them is frequency shift, to control their power output when disconnected from grid.

Multiple SB with PV arrays at different angles would usually flatten power curve, but funny illumination from clouds could cause it to peak higher. You're not supposed to build something that would drive > 56A through each relay. (Configured 2phase4, which would be 4x SI wired 2p2s, current may come close to balancing but not precisely match on parallel paths. I measured 23A on one wire, 24A on the other, last time I checked.)

What I like to do is parallel two PV strings of different orientation into one MPPT. The inverter would clip output to its rating. Penalty for sub-optimum MPPT voltage is about 2% but higher utilization of SCC/inverter (more kWh/day) makes this cost-effective. With Sunny Boy, the MPPT input current is a good fit for single string of larger PV panels, might only work with two if lower amperage. MPPT inputs "A" and "B" can be paralleled, should accommodate 3 parallel strings. Input "C" can't be paralleled.

As you have drawn it, when grid goes down generator would be the only thing powering house. It would also feed SI, recharging batteries. The only thing SI provides battery backup power to is Solar Sub Panel.

On the output of SI you should have Solar Sub Panel (as you do.) That can also serve as Critical Load Panel, e.g. alarm and communication. Only small things that battery can carry through the night, even if only about 10% charge remains, after grid fails and sun has set.

Connect a "Load Shed" relay, from either Critical Loads Panel or from AC wires between SI and Critical Loads Panel. That relay feeds "Important Loads Panel", the things you want to power from battery & PV, such as your house, well pump, A/C. Leave off excessive loads like electric central heating. SI has control relays (two each), and mine uses default load-shed at 70% DoD (for lead-acid.) If battery gets low, and generator was not started to recharge, the house gets disconnected but critical loads and SB remain powered. After sun comes up, it recharges a bit (to 50% DoD) before reconnecting house.

A second stage of load shed is also available. I plan to use that for A/C and laundry, at a higher SoC like 20% DoD.

If you look into Limited Export options, you should be able to use CT on utility wires to measure and keep export < 20kW, through commands to SB. That may be Data Manager and a 3rd party meter. I haven't tried it. I use the (obsolete) Sunny Web Box.

It is best to keep the grid, if only as a generator. It is cheaper and more reliable than gas/diesel generators.
If you do go off-grid (or grid as generator only), 3-phase is an interesting option. 3-phase also works on-grid, but off-grid SMA has "Multi-Cluster", multiple 3-phase islands combining their power to one large island grid. I'm playing with a 3-phase setup, connected to my split-phase grid by only one 120V SI.

 

[crazydane]

Ah ok, I had my drawing above all messed up then. This would be more ideal I believe:



That way, the Shop and House sub-panels are going to take what they want before any excess solar production is pushed through the SIs back into the grid, so WAY less than 54A x 4. Too bad about the communications, but since the SIs regulate the frequency and that SBs sync to that to regulate the power, I should be fine, right?

I could always kill the breakers for some of the SBs if I loose power during the middle of a bright sunny day, so not produce an excessive amount of power that I can't consume. That would keep the frequency from going too high and maybe keep everybody happier?

I would add a load shedding relay to kill the PDUs hanging off the Shop sub-panel, so that in the event I lost power, the mining rigs would go down, which would account for 80-90% of the load at night.

The transfer switch is fully automatic and can be programmed to transfer source on its own, or be controlled externally. I can do generator warm up and cool down, set trigger points, etc:





In my case, I'm not using any of those features, but instead controlling it from the controller on the generator, which is the DSE unit:



It has even more features and functions than the ASCO transfer switch. The main reason I got the DSE, it that particular unit has an Ethernet interface, so I can control from anywhere on my LAN, or via VPN from remote.

So I'm quite certain that between the generator and transfer switch, I can accommodate having the master SI control when the generator needs to run to replenish the batteries.

I agree that I would want to keep my grid connection unless the POCO and/or county inspector gives me a really hard time. I'm not too worried about the POCO, but if they require the new meter base to be inspected before they will connect the power, then I think I'll have issues.

Since I had 400A service at the shop building before, maybe they will let it slide. I'll see if I can chat with them and get a feel for what their expectations are. Perhaps one possibility would be to get a commercial account instead of a residential one, but I suspect the base meter charge will be much higher.

If I add East/West facing strings to my 7 unused MPPT inputs, you're saying I would be better off doing, say 12 facing East and 12 facing West parallel them up, and then connect to input A or B? In my current install with all 60 cell panels, I like to aim for 400V in each string to maximize efficiency.

So having 12E+12W in parallel on input A or B will be better than 12E and 12W on inputs C on 2 difference inverters?

 

[ArkRob]

That pole barn looks exactly like a project I have in mind.

Could I talk you into taking some more details and photos of that?