NEWBIE QUESTION: Long run of wire

[Hedges]

Two different numbers relating to usage: kW peak, and kWh/day.
The system may or may not be well sized to the need.


My system is lopsided in the other direction. PV would refill usable battery capacity in about 1 hour.
Inverter could drain it in about 20 minutes.

 

[cs1234]

Maybe they are going to charge it up with generators everyday to cover the gap. Maybe they have a bunch of horses, cows, young children, etc.. and they are going to make them turn a horse mill of some sort hooked up to wind turbine inputs..

Who knows!

 

[GregTR]

Two different numbers relating to usage: kW peak, and kWh/day.
The system may or may not be well sized to the need.


My system is lopsided in the other direction. PV would refill usable battery capacity in about 1 hour.
Inverter could drain it in about 20 minutes.

That's fair... Maybe I'm too naïve in assuming that most would conform to some kind of "normal" expectation when they could be doing some heavy welding for 10-15 minutes a day and then do nothing but trickle charge their phone all day...

Given how little information the OP divulged on many fronts it's still pretty impressive to see everyone offering all the collective advice for any and all scenarios that may or may not make sense at all.

 

[Hedges]

Other members have had similar loading issues, like a large air compressor.
Given that information, I suggesting smaller motor, run compressor slower for longer time.

We could help him more with more info, out of the box thinking and prior experience.

 

[HPaulPayne]

OP has 24x12Vx120Ah AGM in Montana at 45 degrees latitude with "not very good" winter sun hours.

I doubt that the bottleneck in his setup is going to be the single Sol-Ark 15K....

Building a 48v system for my off-grid workshop

I have a battery bank consisting of 24 12v 120ah AGM batteries series-parallel wired for 48v and 34,560wh total (17,280wh at 50% DOD // 8,640wh at 25% DOD). Will soon have the Aims PICOGLF10KW48V240VS 10,000w 48v split-phase inverter-charger. Using Outback Flexmax 80 charge controllers...

diysolarforum.com

Seems like they're putting lipstick on a pig... But hey, you do you...

I think my main problem (aka "lipstick on a pig') is two-fold.
1) I don't have a lot of knowledge in this field and am on a limited budget for what I am planning to accomplish (champagne tastes - beer budget). Therefore, I am constantly seeking information from whatever reliable sources I can find. This forum is one such source/resource. I don't mind investing the money and time for things that will work. I just can't afford to waste money/time needlessly.
2) As I learn more and as technology rapidly advances, I update my intentions of what I want to accomplish and how I would like to do it. The reason for this is that I am 63 years old, retired, and intend to build an off-grid system that will fulfill all of my needs and outlast me for quite a long time.

For example: My first system was 12v 4000w using a combination of solar and wind. I have upgraded it to 24v 6000w. This is the most power I can send through the size of wires that I have buried in the conduit to my RV hookup and apartment. Fortunately for me, the folks at Missouri Wind and Solar were able to update the 1600w generator and charge controller for the wind turbine. I rewired the 16 6v Trojan batteries [4s4p] and installed a new 24v/6000w Aims split phase inverter/charger. I made some programming adjustments to the two Outback Flexmax 80s and everything is running well. Besides the turbine, I have two strings of three Longi 360w bifacial panels and one string of six 100w panels. The 360w strings are going into the FM80s and the 100s are going into the charge controller for the turbine. This all keeps my 21.6kwh [10.8kwh @50% DOD] battery bank very happy and fully charged much of the time. However, in case of any problem, I do have a 10kw gas/propane generator that is rarely used.

Regarding my new system: As recently as a year ago, I considered going with a 10kw Aims inverter. This was going to be for the shop only. Then, it was suggested to me that I could use a single (larger) system to power both the shop and the house. But I quickly determined that 10kw wouldn't be enough output. I considered using two Outback FM100s and two 8kw Radians. But that (16kw maximum) still was a little low on the output.

Once I learned about Sol-Ark and their inverters, I determined that I could achieve the amount of power that I want if I could use two of the 15kw (12kw while off-grid) units. I am told that these would work with my existing 48v 34.56kwh battery (24 12v AGM) [17.28kwh @50% DOD] and will still work when I upgrade to a larger lithium battery. Although I have 30 400w panels, I am not opposed to adding more panels as needed. I have 80 acres and can find suitable places to mount them if necessary. Plus, I will be adding at least one wind turbine from Missouri Wind and Solar.

Being completely off-grid in Montana, self-sufficiency and overbuilding everything is mandatory. My property is located in the hills (3,700' elevation) more than five miles from a paved road and more than twenty miles to the nearest small town. I need to run large freezers, air conditioning, electric appliances (oven, microwave, dishwasher, washer & dryer, etc.). Some of these can be run on timers, to control overlap power usage. But some, such as the oven, are power-hungry monsters.

If I understand it correctly, a string of ten 400w panels [Jinko JKM400M=72HL-V] wired in series will not work with the Sol-Ark 15k. What if I wired them differently? 5s2p? 2s5p? I'm just shooting in the dark here! As I said, I have limited knowledge and understanding. But I am trying to learn fast.

Also, I found the idea interesting - of using two transformers (240v-480v & 480v-240v) in order to use a smaller wire size. It is something that I will learn more about. I was also reminded that I didn't need to bury/pull a ground wire (if I used a/c for my 1000' run). The idea of installing a smaller motor on my shop air compressor is a good one.

I AM learning. Sometimes slowly. But learning, just the same.

I really appreciate all of the input from the forum members here. The knowledge you are sharing with me is priceless.

Paul

 

[GregTR]

Hey Paul,

Thanks for all that information, it definitely puts some of the things in a better perspective where advice can be offered that is more precise.

While you provided ample data, there are some missing points in there that can be key differentiators in what kind of system you should build, especially if you're on a tighter budget.

First of all, I see no mention of what your total daily consumption is or what it is you're planning on having going forward. This would be the driving factor on the number of solar panels you should have as they would have to provide this amount on average year round for a truly off-grid experience.

Second, you're mentioning shop equipment, compressors and the likes but you're mentioning no peak power requirements. What is your peak power requirement for this system and what drives that? Is it the occasional planer or band saw with a dust collector that you may use a dozen times a year or is it a water pump that has to run every day for several hours?

It is also not clear to me whether you're off-gird at the moment or you're planning on being off-grid with your new setup? If you're on-grid today what is the driving force to be 100% off-grid? Is this a hard requirement? I'm asking because spending $8,200 on a second inverter just because at times you might step over the limit of the inverter is a LOT of money. You can buy a lot of incidental grid power for $8,200 when the occasional need arises. And if the grid goes down, you might want to lay off the wood/metal working for a while and do something else instead. If you're 100% off grid already you can use that 10kW generator for the occasional high power need still, again $8k buys a whole lot of gas/propane still.

As you see, from my perspective you're trying to build a system for "worst case scenario" with costs being exponential rather than linear with needs. You can probably get 80% of what you want for 50% of the cost which would cover 100% of your needs.

Looking at your current system and looking at what you're trying to accomplish the difference is staggering. I'm just trying to understand if this is a want or a need and whether you have other options that might be more economic in the short and long run.

 

[GregTR]

Side note: you do know that you can also do AC coupling on the Sol-Ark up to 19kW (well they have guidelines on the ratio between DC and AC coupled PV for optimal experience, I won't look that up right now for the specifics) and in that AC coupled scenario a single Sol-Ark will cover more than 15kW of power if needed so you're not limited to the 12kW which is the battery only maximum with no AC coupled panels. Unless you're in need of over 12kW of power at night I'm still pretty positive that a single Sol-Ark 15K will cover your needs.

 

[HPaulPayne]

Hey Paul,

Thanks for all that information, it definitely puts some of the things in a better perspective where advice can be offered that is more precise.

While you provided ample data, there are some missing points in there that can be key differentiators in what kind of system you should build, especially if you're on a tighter budget.

My budget is such, that I want to spend/invest the money once and not make major mistakes that would require me to start over having wasted the initial expenditure.

First of all, I see no mention of what your total daily consumption is or what it is you're planning on having going forward. This would be the driving factor on the number of solar panels you should have as they would have to provide this amount on average year round for a truly off-grid experience.

I understand. My daily consumption will vary. So, I am using a "worst case" scenario to figure my needs.

Second, you're mentioning shop equipment, compressors and the likes but you're mentioning no peak power requirements. What is your peak power requirement for this system and what drives that? Is it the occasional planer or band saw with a dust collector that you may use a dozen times a year or is it a water pump that has to run every day for several hours?

The water pumps are on the small system (24v/6000w) and function independently of the large system.

In the shop, I have a commercial bullet casting machine (6000w), air compressor, table saw, band saw, radial arm saw, drill press, etc. etc. etc. Although the bullet machine only runs for 3 -4 hours at a time (once or twice per month), it chews through power. And the air compressor and fans much be running at the same time. Note: I bought and setup a small bullet manufacturing company for my retirement job. ;-)

It is also not clear to me whether you're off-gird at the moment or you're planning on being off-grid with your new setup? If you're on-grid today what is the driving force to be 100% off-grid? Is this a hard requirement? I'm asking because spending $8,200 on a second inverter just because at times you might step over the limit of the inverter is a LOT of money. You can buy a lot of incidental grid power for $8,200 when the occasional need arises. And if the grid goes down, you might want to lay off the wood/metal working for a while and do something else instead. If you're 100% off grid already you can use that 10kW generator for the occasional high power need still, again $8k buys a whole lot of gas/propane still.

Being off-grid is both a necessity and a choice. I'll explain. Power and Internet are available less than a mile down the road. To bring in the electricity, I have been quoted "somewhere around $80,000.00 to $95,000.00. Depending on our costs at the time" by the power company. The fiber Internet will be extra! Then, there are the monthly electricity charges of approximately $300 - $400.

Nope! Not for me! I cannot imagine how anyone can spend that kind of money on power!!! I will spend the money on electricity once and use Starlink for my Internet.

I cannot express how much I appreciate the fact that you are being smart about the costs of my proposed system. Believe me, I don't want to waste money. Especially nowadays.

BTW, everything is costing more lately. Especially fuel. Propane used to be $.99 per gallon a couple of years ago. Now, it is over $3.00 and increasing!!! Anything I can do with self-generated electricity will save me lots of money as time goes on.

As you see, from my perspective you're trying to build a system for "worst case scenario" with costs being exponential rather than linear with needs. You can probably get 80% of what you want for 50% of the cost which would cover 100% of your needs.

Looking at your current system and looking at what you're trying to accomplish the difference is staggering. I'm just trying to understand if this is a want or a need and whether you have other options that might be more economic in the short and long run.

Again, very much appreciated. I would say that it is a combination of both "wants and needs."

Maybe, I should consider less. But this is the last home I will ever have and want to leave my (younger) family a reliable system they can live with, should anything happen to me.

Perhaps I should consider starting out with a single 15k inverter and enlarge it as I need to. But that still leaves me with the question of wiring for 1,000 feet of underground.

Paul

 

[HPaulPayne]

Side note: you do know that you can also do AC coupling on the Sol-Ark up to 19kW (well they have guidelines on the ratio between DC and AC coupled PV for optimal experience, I won't look that up right now for the specifics) and in that AC coupled scenario a single Sol-Ark will cover more than 15kW of power if needed so you're not limited to the 12kW which is the battery only maximum with no AC coupled panels. Unless you're in need of over 12kW of power at night I'm still pretty positive that a single Sol-Ark 15K will cover your needs.

I have NO IDEA what "AC coupling" means. I've heard the phrase. But just don't know.

Paul

 

[cs1234]

I have NO IDEA what "AC coupling" means. I've heard the phrase. But just don't know.

Paul

AC coupling is the ability of the inverter (the sol-ark in this case) to control / manage solar panels that have microinverters on them. Search up microinverters.

 

[Bluedog225]

I have not kept up with all the posts.

Is there no way to have the panels closer?

As you may know, only 5-7 hours of daylight are “good” production hours. Maybe shading is not a problem?

 

[GregTR]

I have NO IDEA what "AC coupling" means. I've heard the phrase. But just don't know.

Paul

It means you can add another string inverter's or a group of microinverters' output to the generator/load input of the Sol-Ark 15K and you can use its power in addition to what the DC coupled PV panels and battery provide.

The Sol-Ark 15K allows up to 19.2 kW of AC coupled power to be passing through in addition to the 12kW from batteries in an off-grid setup.

So theoretically what you win there is that you don't need another expensive hybrid inverter, you can get away with a much cheaper and dumber inverter that does not need to handle battery charging, generator management etc.

Microinverters are ideal because they scale with size, so you can buy as many microinverters as panels you're putting on which scales well should you need to expand the system. The Sol-Ark also does frequency based power management of these micro inverters so they can be used optimally as your power needs fluctuate. Since frequency based power management is not as quick as DC coupled MPPT power management, the DC coupled PV and battery act as buffers to soak up excess power if there is sudden drop in power demand. They also provide the needed sudden surge when sudden power needs arise. It works beautifully. The requirement is generally that your DC side power should be as much as your AC side so it can sink/ramp all the energy you need but depending on surge changes you might get away with a less than 1:1 ratio.

Looks like your large demand is the bullet casting machine at 6kW but only a few times a month for a few hours. This is something a single Sol-Ark 15K with batteries can easily cover and still leave you with 6kW of power for other things. You being in Montana A/C is probably not the largest power suck in your life so that 6kW buffer might be more than enough if you can be cognizant of your usage during those 3-4 hour periods every month.

If you find yourself struggling with getting things done on the 12kW during that time then you can always augment the Sol-Ark 15K with a couple of micro inverters and panels on the AC side and time the 3-4 hour usage for peak PV production hours to be covered by those. Again the beauty of it is that you don't have to invest in it up front, you can expand as you see the need.

Based on what you wrote I'd still recommend you save the money up front on the second Sol-Ark unit and see if you can make do without it. My suspicion is that you can.

As for your original question, I think your best bet is to have the Sol-Ark by the panels and use a transformer to get your AC up to 600V and transfer that over the 1,000 ft distance to the house where you can step it down to 240V and split the phase.

 

[GregTR]

I have not kept up with all the posts.

Is there no way to have the panels closer?

As you may know, only 5-7 hours of daylight are “good” production hours. Maybe shading is not a problem?

I'm getting a solid 10 hours of good production right now in Texas from my panels.


It's all about how you orient your panels.

Now Montana might be significantly different...

 

[GregTR]

Just for fun, I did put a 27x400W panel setup into a modeling software and it would generate 14,500 kWh a year. I coupled it with 33kWh Lifepo battery (too lazy to find an AGM option) in the model and if I assume an average annual consumption of 10,000 kWh (normal for Montana) with a "normal" monthly and daily consumption model pattern you would be able to cover 88% of your usage, you would be under producing in December, January and February but you'd be over producing in all other months.

Now if we add your 3-4 hours a few times a month of 6000W of usage for the tool, you'd still easily cover that in the spring/summer/fall but obviously not in the winter.



Adding more battery would not make a difference, it would allow you to weather marginally longer cloudy periods but overall not really make that much of a difference.

 

[GregTR]

Here is a sample of May and December usages, the gray area ("Net consumption") would have to come from a generator in December or you just need to cut your usage down. You can see that in May there is no "Net Consumption" as you'd be 100% self sufficient. You'd also not "export to grid" that just shows all the excess electricity that you can use to cast ammo shells during the day.

 

[Bluedog225]

Point being, there may be a spot closer than 1000 feet that has good enough mid day sun.

 

[Hedges]

Here is the system I have:

https://files.sma.de/downloads/SI6048US-DS-en-28.pdf

Another way to skin the cat. Note that unlike SolArk, that Sunny Island battery inverter does not have PV input; that would either use separate DC coupled SCC or AC coupled GT PV inverters.
It can be sized to meet your needs, not necessarily cheaper. It does a good job of allowing 100% of PV generated AC plus 100% of available battery generated AC to both be used at the same time (larger daytime loads can be operated in full sun.)

e.g 11.5kW continuous from battery plus up to 24kW from PV for two battery inverters, or double that with four battery inverters and twice the GT PV inverters. (It can manage twice as much AC coupled power as most other brands.)

 

[GregTR]

Given the size of OPs PV array he'll be lucky to get 5kW out of PV at any given time so PV+Battery will not buy him that much more power.

 

[Zwy]

I have not kept up with all the posts.

Is there no way to have the panels closer?

I'm with you on moving panels closer. To tell you the honest truth, given there is a shop that is a large consumer (with large inrush loads) and a house that are 1000 feet apart, it might be a case of being be better served with 2 systems, one for the house, one for the shop. PV array at each location close by.

Considering the loads at the shop, a low frequency inverter would be a better choice for that location. The house may be well served with a pair of HF inverters. I did see where he mentioned he gets water and that seems to be covered unless he wants to integrate it into a new system. An energy audit is necessary, otherwise it is a case of spending money for capability that isn't needed.

As you may know, only 5-7 hours of daylight are “good” production hours. Maybe shading is not a problem?

I always use the 5 hours and anything over that is to be used for recovery from cloudy days or days of high loads.

As for the Jinko JKM400M=72HL-V panels, the VOC of these panels is 49.8VOC and even 9 in series might be too high for some SCC's if the temps get cold. The https://www.midnitesolar.com/sizingTool/ should be used to determine array series connections for those cold winter mornings.

 

[Mattb4]

Reading through this about the OP's shop requirements I would recommend instead of trying for an all solar solution to go part solar and a good quality diesel generator to handle shop loads. Since the shop loads are not an all day thing it likely would be a more economical choice.

For powering the house if the distance must be around a 1000ft transmission explore the possibility of setting poles and running bare conductors.

 

[Hedges]

If the inverters can handle shop loads, and consume limited total kWh, PV and battery able to source the current could do it.
Even if shop loads were a full day occasionally, a battery sized for multiple days autonomy could supply it, with PV recharging over a couple days.

If usage is planned for the long term, years to decades, costs could favor PV.

Diesel generation costs $1.00/kWh, from calculations by one member with PV system and diesel backup. Higher if operated infrequently.

PV + SCC or GT inverter costs $0.025 to $0.03/kWh over 20 years. (assuming you use all power produced, e.g. net metering, or partial PV with generator used daily. Cost higher otherwise.)

Some lithium batteries can cost as little as $0.05/kWh if deep cycled daily for their claimed 3000 or 6000 cycle life, 8 to 16 years.

Lead-acid is $0.25 to $0.50/kWh.

I think PV/battery can have very favorable pricing, if well utilized. Scheduling consumption would improve it, at the expense of convenience and people time. Ideally loads are steady and during the daytime.

 

[HPaulPayne]

It means you can add another string inverter's or a group of microinverters' output to the generator/load input of the Sol-Ark 15K and you can use its power in addition to what the DC coupled PV panels and battery provide.

The Sol-Ark 15K allows up to 19.2 kW of AC coupled power to be passing through in addition to the 12kW from batteries in an off-grid setup.

So theoretically what you win there is that you don't need another expensive hybrid inverter, you can get away with a much cheaper and dumber inverter that does not need to handle battery charging, generator management etc.

Microinverters are ideal because they scale with size, so you can buy as many microinverters as panels you're putting on which scales well should you need to expand the system. The Sol-Ark also does frequency based power management of these micro inverters so they can be used optimally as your power needs fluctuate. Since frequency based power management is not as quick as DC coupled MPPT power management, the DC coupled PV and battery act as buffers to soak up excess power if there is sudden drop in power demand. They also provide the needed sudden surge when sudden power needs arise. It works beautifully. The requirement is generally that your DC side power should be as much as your AC side so it can sink/ramp all the energy you need but depending on surge changes you might get away with a less than 1:1 ratio.

Looks like your large demand is the bullet casting machine at 6kW but only a few times a month for a few hours. This is something a single Sol-Ark 15K with batteries can easily cover and still leave you with 6kW of power for other things. You being in Montana A/C is probably not the largest power suck in your life so that 6kW buffer might be more than enough if you can be cognizant of your usage during those 3-4 hour periods every month.

If you find yourself struggling with getting things done on the 12kW during that time then you can always augment the Sol-Ark 15K with a couple of micro inverters and panels on the AC side and time the 3-4 hour usage for peak PV production hours to be covered by those. Again the beauty of it is that you don't have to invest in it up front, you can expand as you see the need.

Based on what you wrote I'd still recommend you save the money up front on the second Sol-Ark unit and see if you can make do without it. My suspicion is that you can.

As for your original question, I think your best bet is to have the Sol-Ark by the panels and use a transformer to get your AC up to 600V and transfer that over the 1,000 ft distance to the house where you can step it down to 240V and split the phase.

I really appreciate all of the assistance you have offered to me previously and I have taken it to heart.

The idea of adding the use of microinverters and transformers has caused me to really think things out, before throwing money at things.

I have found a source for Enphase IQ8+ and another for Enphase IQ7 and IQ7+ microinverters at a (seemingly) reasonable price. Do you think that either of these can be added to my system (utilizing the Sol-Ark 15k) on the "AC Coupled" side?

Thank you.

Paul

 

[rhino]

Just keep in mind you are adding a lot of additional failure points using those micro inverters.