Off Grid setup details for review - long distance cable to main panel

[Gurusi]

Hey, long time stalker of the forum for information gathering. I am currently considering going off grid and would like some general feedback on my planed setup based on stats/circumstance.

I do have one specific question as regard long distance cable to my house that I have been unable solve based on research…

So I have an acreage (approx. 10 acres), myself and my wife, 2000 sq ft home. In terms of high usage items we have X2 fridge freezers, electric stove, electric hot water heater, Network Acess Storage running 24/7 and a hot tub. All our heating is gas. EDIT + 240v water well pump feeding the house.


I am living in Alberta Canada so things can get cold and less light during the winter months.

I broke down my yearly actual readings from our electric company:-

Yearly:- 13569KWh
Monthly:-1130KWh or 14125KWh (25% buffer added)
Daily:-37.175

I found a formula:- Panel number = kWh usage / production ratio specific to my area / wattage

1412/1.09/550 = 28 panels


Looking at a 48v battery bank calculation (via various websites) I’m estimating 45KWh’s at minimum (I would like more but the cost is crazy)

Due to cost I am looking at pairing 3 lots of 16 3.2v 280ah via the recommended Alibaba sellers on this forum.

My basic equipment list is:

X2 LV6548 in split phase
X4 2P4S Longi 455W panels
A wooden DIY ground mount
3 lots of 16 3.2v 280ah with an appropriate BMS

In terms of VOC and cold climate I found the above array formulation seemed ok for the 250v limit of the inverter (via Midnight solar tool)

VMP @ -40 C 215.6 Volts
VOC @ -40 C 232.8 Volts

My difficulty is that the available land for the solar panels is 170ft from my main electrical panel. The mech room is to the rear of the house meaning running cabling through the hall ceiling.

To make matters more complicated I have no space in my mech room for all of the equipment. I would like to build a shed (well insulated) where the panels are mounted to hold everything and then run the 240 AC cable (L1 L2 and N) to the mech room to hookup to my electrical panel.

Based on research a higher voltage will have less voltage drop? What I can’t figure out is what gauge wire will be needed for the feed. I have a 200amp main panel.

Any thoughts, advice or highlighting errors in the above would be appreciated. The feed to the house is my current sticking point…

Thanks!

 

[RV10flyer]

4 ga minimum. 2 ga best. I chose two EG4 inverters for higher pv voltage input. 4 strings of 7 then.

 

[Gurusi]

Any opinion on whether this setup will last get me through the winter months? Generator research is next

 

[Gurusi]

Anyone?

Thanks

 

[MichaelK]

Your power hogs are the electric stove and the electric hot water heater. Replace those two items and your total consumption will be only a fraction of what you are using now. Since you are already plumbed for gas, I don't see why you don't want to have a gas stove and a gas heater? What does "NAS" mean? Please don't use acronyms if you don't define them first.

Judging by my own system which consumes no more than about 4kWh per day, I'd say with gas appliances you could go from 37kWh/D to 5-6kWh/D. Then there's the well-pump. What are the specifications on that? When does it run? I have a 1hp 240VAC pump which I run with my XW+6848 inverter. I use the 2X rule for installing panels. That is, whatever your single largest load is, install 2X the amount of panels to run it. My well-pump needs about 2200W of power to run (9100W startup), so I installed 4500W of panels. That was first with a 48V 400Ah Trojan L-16 battery bank.

Your best option is to keep the electronics nearby, but position the panels in the location of best sun. In my case, I'm running my arrays with 4 30V panels in series to get 120VDC. This goes 130' through 10 gauge wire to the controller, which is in the same area as the batteries. In your case, you could wire 5 panels in series to get 150VDC, which at -40 degrees will only reach ~235Voc. Since you are using Midnight's calculator already, go head and plug in those numbers for your site-specific number.

The Midnight250 has an amp limit of 55A at 48V, so you could install 55A X 50Vcharging X 1.175x fudgefactor = 3230W of panels. Call that 12 260W grid-tie panels. You can copy my rotating mount design, which can hold 6 panels. Two of those will carry everything you need. Rotating though allows you to overpanel. You can chose to point one array SE, another S, and the third SW. This will tend to dampen your noon amperage peak, but spread out the amperage curve over a longer part of the day. It really helps the most on cloudy days when production is marginal at best. And, it's just fun to rotate the arrays East to West to see how you can maximize production at a given moment. That's especially important when you want to run your well-pump.

 

[Gurusi]

Your power hogs are the electric stove and the electric hot water heater. Replace those two items and your total consumption will be only a fraction of what you are using now. Since you are already plumbed for gas, I don't see why you don't want to have a gas stove and a gas heater? What does "NAS" mean? Please don't use acronyms if you don't define them first.

Judging by my own system which consumes no more than about 4kWh per day, I'd say with gas appliances you could go from 37kWh/D to 5-6kWh/D. Then there's the well-pump. What are the specifications on that? When does it run? I have a 1hp 240VAC pump which I run with my XW+6848 inverter. I use the 2X rule for installing panels. That is, whatever your single largest load is, install 2X the amount of panels to run it. My well-pump needs about 2200W of power to run (9100W startup), so I installed 4500W of panels. That was first with a 48V 400Ah Trojan L-16 battery bank.

Your best option is to keep the electronics nearby, but position the panels in the location of best sun. In my case, I'm running my arrays with 4 30V panels in series to get 120VDC. This goes 130' through 10 gauge wire to the controller, which is in the same area as the batteries. In your case, you could wire 5 panels in series to get 150VDC, which at -40 degrees will only reach ~235Voc. Since you are using Midnight's calculator already, go head and plug in those numbers for your site-specific number.

The Midnight250 has an amp limit of 55A at 48V, so you could install 55A X 50Vcharging X 1.175x fudgefactor = 3230W of panels. Call that 12 260W grid-tie panels. You can copy my rotating mount design, which can hold 6 panels. Two of those will carry everything you need. Rotating though allows you to overpanel. You can chose to point one array SE, another S, and the third SW. This will tend to dampen your noon amperage peak, but spread out the amperage curve over a longer part of the day. It really helps the most on cloudy days when production is marginal at best. And, it's just fun to rotate the arrays East to West to see how you can maximize production at a given moment. That's especially important when you want to run your well-pump.

Thanks for looking over my proposed setup, appreciated. The electric stove and water heater came with the house so we will definitely swap out to natural gas in the future. A NAS is network access storage (multiple hard drives running 24/7) ive edited my post from acronym.

The pump is a deep well submersible 1hp 240v running on a 20amp breaker. I would need to dig out the manual for specs in terms of consumption. The well feeds to a large expansion tank and refills/powers the pump as needed (it is our main drinking water supply).

I am currently trying to find the best balance in terms of panel location (for sun), shed location and hookup to our main panel. We want the panels fairly far away but don't want to pay out lots of large gauge wire or suffer massive voltage drop.
Its tricky jumping to off grid with an assessed setup and a lot of variables involved. We dont want to end up supper short on supply or in need of further equipmet/expenses.

 

[MichaelK]

The pump is a deep well submersible 1hp 240v running on a 20amp breaker. I would need to dig out the manual for specs in terms of consumption. The well feeds to a large expansion tank and refills/powers the pump as needed (it is our main drinking water supply).

I am currently trying to find the best balance in terms of panel location (for sun), shed location and hookup to our main panel. We want the panels fairly far away but don't want to pay out lots of large gauge wire or suffer massive voltage drop.
Its tricky jumping to off grid with an assessed setup and a lot of variables involved. We dont want to end up supper short on supply or in need of further equipmet/expenses.

Sounds like your pump is basically the same as what I myself am running. The specs of my 1hp pump are 9.5A running, with 38A starting, at 240V. It's very typical for pumps to have very high startup surge. Mine is 9100W. For whatever inverter you select, study it's surge capacity carefully. AiO inverters are typically high-frequency transformerless models with little or no starting surge. Some try to cheat. They'll claim their unit can surge to 200%. They don't tell you that it can surge to 200% for only 16 milliseconds. Quality inverters will be able to surge up to 200% for 5-60 seconds.

Take a close look at Outback's Radian, and Schneider's XW-Pro. I have the XW+ and it starts my well pump effortlessly.

Use this voltage drop calculator to determine what your losses will be with a certain gauge of wire at a certain voltage. As I said, I'm running 120VDC through 10 gauge wire for 130 feet, and I see no measurable voltage drop. It may actually cheaper to put one more panel in series to compensate for voltage drop, and use thinner wire then you were expecting. It's all doable.

 

[Gurusi]

Thanks, I was not aware of the starting surge for the pump. I had been set on X2 LV6548's in split phase. Specs say surge power 13kw (5 seconds ) or 26kw for two inverters in parallel so should be ok (will check my pump specs).

Yep extra panels make sense to account for the drop with thinner cables. Spent time playing with different lengths/gauge for the AC and DC side of things last night. I am looking at below 3% for the array side ideally. I read somewhere that the AC side should be below 0.5 volts ideally, but that is going to be very chunky gauge wire.

 

[MichaelK]

You don't have to assume our pumps are exactly the same. You can determine your own starting surge with the right tools. What you need is a clamp meter that can accurately measure "inrush current". Inrush is the huge peak that motors draw in the first 500 milliseconds or so at startup to overcome inertia. I've had a couple of different inrush meters. Now I'm using this one.

UNI-T UT216C 600A Digital Clamp Meters NCV LCD Test ACDC Auto Range Multimetsâ¦Kd | eBay

Specifications Range UT216C. AC current (A) 600A ±(2.5%+5). DC current (A) 600A ±(2.5%+5). Jaw opening ã 30mm. Analog bar graph. VFC, low pass filter. Why Choose us. Display count ã 6000.

www.ebay.com

You place the clamp over ONE of the hot wires, either L1 or L2, set the display to "inrush", then flip on the pump. The surge current in amps will be displayed. A regular clamp meter is not fast enough to catch the starting surge, so it won't display anything until the surge is finished.

I think your best performance is going to be had with long distance DC, paired with short distance AC. Place your solar arrays in the best possible position, and wire six panels in series for ~180VDC. The Voc at -40 degrees will be ~225Voc, but please reconfirm this with Midnight's string calculator. Alternatively, there are other component controllers that ratchet that to between 300V to 600V. Look at Outback's Flexmax 300, Morningstar’s TriStar MPPT 600V charge controller (TS-MPPT-600V), or Schneider's XW-MPPT80-600. A LOT more money though.

Deliver the raw high-voltage solar to the controller, then have the batteries and the rest of the system positioned just inches away. That will reduce resistance losses to a minimum.

 

[Gurusi]

Hey, thanks again. Had been looking for a clamp meter but wouldn't have known to look for the inrush feature. Just ordered the UT216C.

 

[JRH]

Hey, long time stalker of the forum for information gathering. I am currently considering going off grid and would like some general feedback on my planed setup based on stats/circumstance.

I do have one specific question as regard long distance cable to my house that I have been unable solve based on research…

So I have an acreage (approx. 10 acres), myself and my wife, 2000 sq ft home. In terms of high usage items we have X2 fridge freezers, electric stove, electric hot water heater, Network Acess Storage running 24/7 and a hot tub. All our heating is gas. EDIT + 240v water well pump feeding the house.


I am living in Alberta Canada so things can get cold and less light during the winter months.

I broke down my yearly actual readings from our electric company:-

Yearly:- 13569KWh
Monthly:-1130KWh or 14125KWh (25% buffer added)
Daily:-37.175

I found a formula:- Panel number = kWh usage / production ratio specific to my area / wattage

1412/1.09/550 = 28 panels


Looking at a 48v battery bank calculation (via various websites) I’m estimating 45KWh’s at minimum (I would like more but the cost is crazy)

Due to cost I am looking at pairing 3 lots of 16 3.2v 280ah via the recommended Alibaba sellers on this forum.

My basic equipment list is:

X2 LV6548 in split phase
X4 2P4S Longi 455W panels
A wooden DIY ground mount
3 lots of 16 3.2v 280ah with an appropriate BMS

In terms of VOC and cold climate I found the above array formulation seemed ok for the 250v limit of the inverter (via Midnight solar tool)

VMP @ -40 C 215.6 Volts
VOC @ -40 C 232.8 Volts

My difficulty is that the available land for the solar panels is 170ft from my main electrical panel. The mech room is to the rear of the house meaning running cabling through the hall ceiling.

To make matters more complicated I have no space in my mech room for all of the equipment. I would like to build a shed (well insulated) where the panels are mounted to hold everything and then run the 240 AC cable (L1 L2 and N) to the mech room to hookup to my electrical panel.

Based on research a higher voltage will have less voltage drop? What I can’t figure out is what gauge wire will be needed for the feed. I have a 200amp main panel.

Any thoughts, advice or highlighting errors in the above would be appreciated. The feed to the house is my current sticking point…

Thanks!

It appears that about 3500.00 dollars would solve the problem even if you had to use 4/0 cable. Ten bucks (at todays prices ) per ft x 170 ft x 2 cables…and I doubt you would have to…I was just using a worst case scenario…
I haven’t done the numbers ,but 1/0 at the right voltage is where you will probably end up… maybe 2/0 ….I had a similar issue and just went with 1/0 .. cost about a grand for 100 ft x2 cables of real good high strand wire…conduit is a few hundred more depending on what type.
I did use larger cable than I needed so as to build in for future panels, upgrades and less voltage drop.
I wish you luck in the venture….
J.

 

[Gurusi]

It appears that about 3500.00 dollars would solve the problem even if you had to use 4/0 cable. Ten bucks (at todays prices ) per ft x 170 ft x 2 cables…and I doubt you would have to…I was just using a worst case scenario…
I haven’t done the numbers ,but 1/0 at the right voltage is where you will probably end up… maybe 2/0 ….I had a similar issue and just went with 1/0 .. cost about a grand for 100 ft x2 cables of real good high strand wire…conduit is a few hundred more depending on what type.
I did use larger cable than I needed so as to build in for future panels, upgrades and less voltage drop.
I wish you luck in the venture….
J.

Thanks for confirming I'm on the right track, good to know before you start purchasing. I'm still mentally moving the location of the array and shed to look at combos that provide minimal voltage drop and don't cost the earth!

I was looking at USEI90 600V 1/0awg, seems good based on my numbers. just hoping there is enough flexibility as there are a few 90 degree internals to work around. I was looking at a three conductor cable (L1,L2 and N). Are there any benefits to two single live cable runs?

 

[JRH]

Thanks for confirming I'm on the right track, good to know before you start purchasing. I'm still mentally moving the location of the array and shed to look at combos that provide minimal voltage drop and don't cost the earth!

I was looking at USEI90 600V 1/0awg, seems good based on my numbers. just hoping there is enough flexibility as there are a few 90 degree internals to work around. I was looking at a three conductor cable (L1,L2 and N). Are there any benefits to two single live cable runs?

He guy, I’m not here to give tech advise here as much as I was saying that with all your Gona spend on gear , the wiring for a 170 ft run isn’t a money deal breaker… AND yes my flex 1/0 will do any bend you want to do but there are rules you need to reference about the amount of bend permitted ..I looked at it the other night and I’m not bending near enough to cause a problem , but I could…i just don’t need to…
yes there are some differences when cables run together vs separately or perhaps twisted and the temp ratings allowed and water and insulation temp rating snd wether it’s groundhog proof and Blaa Blaa ….and much more ( you should research that part ) .there are whole pages of charts and theory on that available. Some of it is in the code.

there are so many rules , it makes my head spin…and more is coming too…

all I know is over buy on everything I can to have head room In size and quality …If everything is running cool, not stressed and obviously working well , it is a happier solar system , or diesel engine or PA system, or motorcycle ,or marrage, or about any other “ system” ….

there a plenty of very smart and helpful guys on this site that are qualified to help you with the smallest details and they will be around at some point to advise...

good luck, jim.

 

[MichaelK]

It appears that about 3500.00 dollars would solve the problem even if you had to use 4/0 cable. Ten bucks (at todays prices ) per ft x 170 ft x 2 cables…and I doubt you would have to…I was just using a worst case scenario…
I haven’t done the numbers ,but 1/0 at the right voltage is where you will probably end up… maybe 2/0 ….I had a similar issue and just went with 1/0 .. cost about a grand for 100 ft x2 cables of real good high strand wire…conduit is a few hundred more depending on what type.
I did use larger cable than I needed so as to build in for future panels, upgrades and less voltage drop.
I wish you luck in the venture….
J.

I have no clue what you are thinking here? Suggesting 4/0 cable for a run 170'? Plugging those numbers into a voltage drop calculator, using the recommended voltage results in less than 3V of drop. I would consider that totally insignificant. I see 200' of 10 gauge wire on Ebay right now for 156$. Call that 312$ for 200' each of red and black.

 

[JRH]

I have no clue what you are thinking here? Suggesting 4/0 cable for a run 170'? Plugging those numbers into a voltage drop calculator, using the recommended voltage results in less than 3V of drop. I would consider that totally insignificant. I see 200' of 10 gauge wire on Ebay right now for 156$. Call that 312$ for 200' each of red and black.
View attachment 107306

It was a worse case scenario.. I clearly said that… did you read the whole comment .?.. I also, without knowing all pertinent details other than that one part addressed,said it would probably be about 1/0 as a safe guess ..it’s what I used for 86 volts and 22 amps at 100 ft…….I could have squeezed by with less , but I didn’t.. I like things overbuilt…it’s the way I do stuff.
.What about future upgrade or possible change of voltage for several reasons. Or increase in amperage…, unknown code limitations in the future..??? …
“ a worst case scenario“ should always be considered in all endeavors in life ….that data point should be considered in the developmengal stage ,not a after the fact discovery…

also three % percent V drop is like trying to make a score of 70 on a test in school.. . one should aim much for better than a minimum Passing grade , But then to each his own as far as the pursuit of excellence in their crafts.
Thats what I was thinking, Sir.

Jim.

 

[MichaelK]

also three % percent V drop is like trying to make a score of 70 on a test in school.. . one should aim much for better than a minimum Passing grade , But then to each his own as far as the pursuit of excellence in their crafts.
Thats what I was thinking, Sir.

Jim.

Three % V drop? Did you read my whole comment? I said less than 3V of drop. Did you look at the analysis I cut and pasted. It states 1.57% drop.
Doesn't appear to be much thought here?

 

[JRH]

Three % V drop? Did you read my whole comment? I said less than 3V of drop. Did you look at the analysis I cut and pasted. It states 1.57% drop.
Doesn't appear to be much thought here?

Shucks , don’t be so hard on yourself , kindly have a nice day…

 

[Gurusi]

Due to constraints on my land I considered running 110v AC out to my main panel. One single expensive cable at a higher voltage (less loss) seemed attractive. 1/0 seems fine with little loss.

With DC/solar array I would be running X4 strings or 8 lengths of cable over 170ft.

I changed the length from 170ft to 340ft on the calculator states "one way" and my understanding was that you account for the the + and - cable.
Am I correct? .

 

[Gurusi]

10 gauge and even 8 gauge seem to be too much voltage loss. I imagine the price for 1360ft of 6 gauge wire will be expensive. Probably more than a single run of 1/0?

 

[JRH]

Due to constraints on my land I considered running 110v AC out to my main panel. One single expensive cable at a higher voltage (less loss) seemed attractive. 1/0 seems fine with little loss.

With DC/solar array I would be running X4 strings or 8 lengths of cable over 170ft.

I changed the length from 170ft to 340ft on the calculator states "one way" and my understanding was that you account for the the + and - cable.
Am I correct? .

Better Check on that doubling the distance you did . The calculates shown earlier in this thread is very popular and the one I usually use. Most of the calculators I have seen and used ,anticipates the return footage. Some will say “ enter distance in feet one way” others will say list distance “round trip.”. In the old days printed tables sometimes were confusing about that so double check.

If it says “one way “ then put in 170ft and it is normally building in the round trip calculation (340 ft ) for you ( for the other wire returning) I always use two or three calculators to see if the all jive…I verify the answer…mistskes and glitches do happen……Hope that helps , until your more solid in knowledge you should verify anything you hear unless you are very confident about what you heard …. Verify- verify - verify…. It’s your money , not theirs.
Jim.