Best way to run AC power 500 ft from array to cabin

[Quattrohead]

High voltage DC is a non starter, the whole world figured that out 100 years ago !!! Yes yes there are a few where connecting one large grid to another in sync is impossible, UK to Europe for example.
Are you totally 100% sure you cannot put panels and inverters at each building ? I would look into this again.

 

[noenegdod]

High voltage DC is a non starter, the whole world figured that out 100 years ago !!! Yes yes there are a few where connecting one large grid to another in sync is impossible, UK to Europe for example.
Are you totally 100% sure you cannot put panels and inverters at each building ? I would look into this again.

False, if your starting with DC, like we are with a solar panel.

If your are starting with DC from the panels, just distribute that and then convert. Starting with DC, converting to AC, then stepping up, distributing and then stepping down is crazy.

 

[Don B. Cilly]

They sell this at the local hardware store, 650€, 150 lt. tank.

It includes the bracket. Not any tubes. They have bigger ones. Maybe not all that efficient in Alaska, but it's impressive what they do with very little sun.

 

[AlaskanNoob]

Stupid reality! Getting in the way of all my hopes and dreams!

I getcha. Some thoughts to throw out there though:

What about a solar water heater, the tubes-sitting-in-the-sun type, not the electric type. If you can pre-heat most of your hot water via free solar then you could save a butt-ton of energy on the heating elements. My dad made one when I was a kid out of an old hot water tank spray painted flat black, some of the mylar coated insulation foam, a plywood box, and a sheet of plexiglass. No need to fork out big moneys that might be spent better elsewhere.

I don't think you can take 2 120v lines, combine them to a 220v for the transformer, bump them up to ZOMGVolts, then split them back out to dual lines again on the other end. You'll have to have a transformer with coils for all 3 wires separately, but most commercially available split phase transformers should have lugs for all those.

Something to factor in also is that unless you track down the special high-voltage wire, almost all of your commercially available wire is only rated for 600v, so strapping that to a 900v transformer will not end well.

Doing the step-up makes sense logically, you just need to figure out if the cost of the fatter wire for 220v is more expensive than 2 transformers (one for either end).

Solar water heating water 500 feet away from our cabin and porting that water 500 feet would be interesting to discuss in a different thread. In this one we'd like to explore AC electrical transmission over 500 feet.

Thank you for the discussion of AC power and transformers.

 

[John Frum]

High voltage DC is a non starter,

Why?
What is your reasoning?

 

[AlaskanNoob]

If it was me, I'd be running lower current 24 hours a day instead of a few hours at peak current. Then, I don't do anything the way other people do here.

I don't understand how this applies to our situation. How do we run lower current 24 hours day including at night with a PV system using AC power?

 

[AlaskanNoob]

If that were my system, I would definitely be working on running high voltage DC to the house. Instead of a bunch of transformers, and added industrial equipment, I would stack the panels voltage up, and run it into a high voltage solar charge controller at the house.

The only two viable options that I can see are either very large transformers, or a high voltage DC configuration.

This thread was supposed to be about running AC power. Not DC power which we discuss in another thread.

 

[AlaskanNoob]

For a lot of very useful information on solar water heating (not using electricity) go to
https://www.builditsolar.com
BobK53

This thread isn't supposed to be about solar water heating. Our hope was to use it for discussing transmitting AC electrical power 500 feet.

 

[AlaskanNoob]

High voltage DC is a non starter, the whole world figured that out 100 years ago !!! Yes yes there are a few where connecting one large grid to another in sync is impossible, UK to Europe for example.
Are you totally 100% sure you cannot put panels and inverters at each building ? I would look into this again.

This thread is supposed to be about running AC power 500 feet. We are trying to explore that option in this thread.

 

[AlaskanNoob]

They sell this at the local hardware store, 650€, 150 lt. tank.
View attachment 81052
It includes the bracket. Not any tubes. They have bigger ones. Maybe not all that efficient in Alaska, but it's impressive what they do with very little sun.

Heating water and transmitting it 500 feet to our cabin would be a fascinating topic for another thread. In this thread we'd like to explore running AC power 500 feet.

 

[12VoltInstalls]

but I honestly think that the strategy that needs revising is the energy usage.
What you're planning seems - to me - utterly ludicrous.

Ya, I’d agree. I’m following this because it’s like a reality show- crazy electric demand imho. I can’t imagine, never mind the seasonal long, long, long weeks of night

 

[AlaskanNoob]

Ya, I’d agree. I’m following this because it’s like a reality show- crazy electric demand imho. I can’t imagine, never mind the seasonal long, long, long weeks of night

We'll start a new thread on why people shouldn't use solar but should instead rub sticks together to start fire to heat themselves and dry their clothes on a clothes line, but in this thread we're hoping to explore how to transmit AC power 500 feet.

 

[noenegdod]

We'll start a new thread on why people shouldn't use solar but should instead rub sticks together to start fire to heat themselves and dry their clothes on a clothes line, but in this thread we're hoping to explore how to transmit AC power 500 feet.

Its not difficult and the options have been clearly discussed. The audience is getting bored telling you its not really a good option.

 

[AlaskanNoob]

Its not difficult and the options have been clearly discussed. The audience is getting bored telling you its not really a good option.

You know what else isn't difficult? Staying on topic. And if you think they're bored telling me this isn't a good option, imagine how bored I am explaining that this thread is meant to discuss that option so we can determine for ourselves what is the best option.

I wouldn't want the audience (that chooses to click on a thread titled "Best way to run AC power 500 ft from array to cabin") to get bored. Looking forward to more links to solar water heaters and discussion of propane please. The audience must be entertained.

​

 

[MrsAlaskanNoob]

Something to factor in also is that unless you track down the special high-voltage wire, almost all of your commercially available wire is only rated for 600v, so strapping that to a 900v transformer will not end well.

Appreciate this input, thanks. I *think* I've found 2000volt rated wire. We'd have to do the price comparison on whether smaller size, 2000v-rated is more cost-effective than larger wire, 600v rated.

 

[AlaskanNoob]

Appreciate this input, thanks. I *think* I've found 2000volt rated wire. We'd have to do the price comparison on whether smaller size, 2000v-rated is more cost-effective than larger wire, 600v rated.

I'm confused. How is that wire going to plug into the solar water heater?

 

[MrsAlaskanNoob]

Ya, I’d agree. I’m following this because it’s like a reality show- crazy electric demand imho. I can’t imagine, never mind the seasonal long, long, long weeks of night

I hear everyone who is saying the demand is crazy high. I don't know how else to figure it except add up worst case numbers for all of the appliances we want. Absolutely agree that we may not end up having the power for it (esp in winter). But what I don't want is to have a day where we have a ton of power and not be able to turn everything on b/c we didn't run big enough wires. Also, future proofing is essential, I think, when we're talking about trenching wire 500 feet.

Do I want to live off-grid like I'm on-grid? Yes. Is that feasible? Maybe not. But in my view it's worth a shot.

 

[12VoltInstalls]

We'll start a new thread on why people shouldn't use solar but should instead rub sticks together to start fire to heat themselves and dry their clothes on a clothes line, but in this thread we're hoping to explore how to transmit AC power 500 feet.

OK. I didn’t realize you were also considering reasons why you shouldn’t use solar! I’ll watch for the thread.

It seems you have your own way of looking at things which is fine. (I use a bic lighter or matches to start a fire, btw). I wish for your success.

Nevertheless, and with no ill intentions in my statement, you do have to realize with your huge kW demand, the distance, and the terrain challenges it makes your system quite unusual and outside the norm. That makes it interesting- perhaps fascinating- to people. Being defensive about these unusual characteristics seems a bit odd because, well, it IS VERY unusual, and further unusual that you seem likely to complete the project. Often- once the scale and complexity is realized- people abandon their goal once the scope and cost overwhelmed them.
Sorry to have offended you.

 

[Hedges]

OK, you can tell me to go take a hike, but I honestly think that the strategy that needs revising is the energy usage.
What you're planning seems - to me - utterly ludicrous.

Their system is meant to harvest all the PV they can during a short Alaskan winter day, and use the power 24/7 for a ground-source heat pump.
Optimal PV location is on a hill 500' away from house which gets much less sun.
PV array will be 22kW (of course reduced output with low winter sun.)

Steady-state AC power is therefore 1/6 as much as steady-state PV production (not counting things like cooking appliances.)
AC needs to send some motor starting surge current so voltage drop matters. Heat pump is thought to be soft-start except maybe for a fan.

If using 600V max SCC (or PV inverters), operating voltage Vmp is probably around 400V, not quite twice 240Vrms AC. So power losses a bit more than 1/4 of AC. For the same power, but handling 6x the power. Close to being a wash, PV DC vs. 240VAC over the wires.

AC stepped up to 480Vrms seems like it comes out ahead. Higher voltage than DC and 1/6 the (average) power.
960Vrms can be accomplished with a pair of 480/240V transformers. 4x the voltage, 1/16th the power loss for same wire. Or 1/16th as large a wire (much cheaper)
With any kind of system located at the PV array, AC including starting surge is distributed by transformer.
If an AC coupled system, GT PV inverter and 2x 480/240V transformer at PV array, grid-forming battery inverter at house.

12kW/960V = 12.5A
1000' of 12 awg = 1.6 ohms
12.5A x 1.6 ohms = 20V IR drop in wires.
20V/960V = 2.1% loss (at 12kW AC)

1000' of 12 awg costs $185. Actually, should have 1500' and one for ground.

We'll start a new thread on why people shouldn't use solar but should instead rub sticks together to start fire to heat themselves and dry their clothes on a clothes line, but in this thread we're hoping to explore how to transmit AC power 500 feet.

Its not difficult and the options have been clearly discussed. The audience is getting bored telling you its not really a good option.

Quite easily, actually.

$534 gets you 5kW 480V to 120/240V. Two of those would do 960V (centertap grounded) to 120/240V
This handles 10kW, bit more money for two 7.5kW to handle 15kW, or less voltage drop at 10kW.

1-Phase 240x480v Pri 120/240v Sec Encapsulated Transformer

This resin-encapsulated transformer converts 1-phase 240V or 480V to 1-phase 120/240V. Encapsulated units are perfect for dusty, wet, or corrosive environments.

store.maddoxtransformer.com

Same thing hooked up reverse would boost 240V to 960V.
An issue is voltage ratios aren't exactly that, probably meant to make a few percent above 120/240V no-load, so used opposite direction is a few percent low. Some transformers have taps to adjust that. Your inverter may have an adjustment to output voltage. Many appliances (e.g. your heat pump) would be designed for 208V as well as 240V systems, so could tolerate lower voltage.

At $1060 (for each of your 3 locations) for two transformers, doesn't seem bad at all. I think that and $250 of wire for one run is less than you expected to pay for wire alone.

 

[AlaskanNoob]

OK. I didn’t realize you were also considering reasons why you shouldn’t use solar! I’ll watch for the thread.

It seems you have your own way of looking at things which is fine. (I use a bic lighter or matches to start a fire, btw). I wish for your success.

Nevertheless, and with no ill intentions in my statement, you do have to realize with your huge kW demand, the distance, and the terrain challenges make your system quite unusual and outside the norm. That makes it interesting- perhaps fascinating- to people. Being defensive about these unusual characteristics seems a bit odd because, well, it IS VERY unusual, and further unusual that you seem likely to complete the project. Often- once the scale and complexity is realized- people abandoned the goal when the scope and cost overwhelmed them.
Sorry to have offended you.

You haven't offended me. But I would like to keep this thread useful to the topic at hand.