100 amp sub-panel, 600 ft from source

[jaggedben]

The he would not need to consdier the voltage-drop/wire sizing for 100A either! Correct?!

Correct. Nor would he need to dig a ditch. Or install 600 ft of any large conductors.

Complete with battery bank?

Possibly. I may have low-balled it a bit.

 

[jaggedben]

I just wanted to make sure i had the numbers in perspective. For similar costs as a 24KW install, 600 feet of fat wire (or skinny wire and xfms), ditch, replacing the grass, feeders, disconnects, and panels, the customer can get about 2.4KW on Solar.

ice

2.4kW of grid-tied solar is often enough to supply the annual energy consumption of a one-family home which might have a 200A service. (An offgrid system will need to be somewhat bigger to supply the same consumption.) As has been asked from the beginning of this thread, does the customer really need 100A at 240V (and how often)? It is quite pertinent no matter which of the suggested solutions are being considered.

 

[jaggedben]

Possibly. I may have low-balled it a bit.

I should add that it's difficult to figure batteries into a $/W figure because you are paying for watt-hours, not watts. It would depend on what the system was designed for, (which is still the big mystery in this thread).

 

[weressl]

Correct. Nor would he need to dig a ditch. Or install 600 ft of any large conductors.

Since we are no longer talking about 100A load, the wire size would proportionately reduced. DitchWitch daily rental <$170.00.

Possibly. I may have low-balled it a bit.

It is funny how it always seem to happen. So what is the cost of a sustained 24kW system. We can always start with the high and work ourselves down to what maybe acceptable and compare that with hardwired installation.

 

[weressl]

2.4kW of grid-tied solar is often enough to supply the annual energy consumption of a one-family home which might have a 200A service. (An offgrid system will need to be somewhat bigger to supply the same consumption.) As has been asked from the beginning of this thread, does the customer really need 100A at 240V (and how often)? It is quite pertinent no matter which of the suggested solutions are being considered.

It has already been established that the service is 100A and the wire is sized for that.

 

[jaggedben]

So what is the cost of a sustained 24kW system.

No one said it needed to be sustained. The cost would depend highly on whether that was true or not. I'm not going to get into an off-grid solar discussion lacking info about actual loads and usage. People design utility connected systems that way, but no one designs off-grid solar that way.

It has already been established that the service is 100A and the wire is sized for that.

I'm not the first person in this thread who asked how that number was arrived at.

 

[iceworm]

2.4kW of grid-tied solar is often enough to supply the annual energy consumption of a one-family home which might have a 200A service. ....

Color me a bit skeptical on this. I'm assuming you are considering no capital payback, no maintnenance costs, the sun is always equivalent to noon-in-June-Arizona, gas heat and hot water, no air conditioning. Oh and a state where the Utility is mandated to subsidize by paying way above the rate for buying power.

... As has been asked from the beginning of this thread, does the customer really need 100A at 240V (and how often)? ...

I don't know. 100A was the spec. If she only needed it once - isn't that enough. I've got a 100A feed out to my shop. I wouldn't like it if my table saw wouldn't run. I can imagine my customers attitude if they speced 100A and I told them, "I put in 10A, but it will cost you the same as if it were a 100A."

... It is quite pertinent no matter which of the suggested solutions are being considered.

It could be. And I just don't know how. With the exception of small, near constant load, remote sites, I've just never seen a solar install that had a pay back. Most any other power source is preferable - well, maybe with the exception of wind, that might be worse.

Then again, maybe today is the day I get educated.

ice

 

[weressl]

No one said it needed to be sustained. The cost would depend highly on whether that was true or not. I'm not going to get into an off-grid solar discussion lacking info about actual loads and usage. People design utility connected systems that way, but no one designs off-grid solar that way.

I'm not the first person in this thread who asked how that number was arrived at.

Sorry, it was you who proposed that as an alternative.

In an open and honest -- not to mention unbiased discussion -- there should be no question that does no merit a straightforward answer. Alas that is not the case, on many levels, and I find this quite frequently with alternate enegy supply folks.

 

[ActionDave]

It has already been established that the service is 100A and the wire is sized for that.

I'm betting the calculated and actual load are no where near that, making the fat wires unnecessary.

 

[jaggedben]

Color me a bit skeptical on this. I'm assuming you are considering no capital payback, no maintnenance costs, the sun is always equivalent to noon-in-June-Arizona, gas heat and hot water, no air conditioning. Oh and a state where the Utility is mandated to subsidize by paying way above the rate for buying power.

You seem to have considerably misunderstood what I said, because you've mentioned a bunch of financial issues which are irrelevant because the statement was purely about kWh. It's true that houses with electric heat and large AC usage will probably need a larger system, although it also depends highly on the resident's habits. Your statement about sun is simply not true.

don't know. 100A was the spec. If she only needed it once - isn't that enough. I've got a 100A feed out to my shop. I wouldn't like it if my table saw wouldn't run.

If you're a one man operation and only using one power tool at a time, you don't really need 100A of power, even if you would use that many amps if all your machines were on at the same time. If the outbuilding is a small woodshop for hobby type work, a 1-2kW solar system might actually be totally sufficient for the actual load and usage, and cheaper than a 100A 600ft feeder. There might occasionally be moments when the system runs out of power, but they might be few and far enough between to be worth the saved money. It all depends on the usage.

Now if the customer wants 100A to run a fridge and AC and lights all night in this outbuilding, then yes, the solar probably won't cut it.

With the exception of small, near constant load, remote sites, I've just never seen a solar install that had a pay back.

Come to California where electricity can cost up to 40cents/kWh.

Then again, maybe today is the day I get educated.

Look, I just threw it out there for the OP to consider. There isn't enough information from the OP to know whether the answer will be favorable to solar or not, and I never asserted that it necessarily would be.

 

[jaggedben]

Sorry, it was you who proposed that as an alternative.

In an open and honest -- not to mention unbiased discussion -- there should be no question that does no merit a straightforward answer.

I'm simply not going to waste my time assuming specs that might not be what the customer actually needs. If the OP comes back this discussion with more information, I might offer some more specific advice.

 

[iceworm]

I'm betting the calculated and actual load are no where near that, making the fat wires unnecessary.

Okay, define "no where near", 50%? 10%?

In any case, I'm sure you are right - the actual load will be less than the requested 100A. I don't know if it is 99A (peak) or 50A (not so peak). So, what number are you going to pick?

Neighbor sees me out working and walks over. "Hey worm, I'm building a shop down on my lower 40. It's about 600 feet to power. I'd like a 100A service. Can you work up a budget price for me?"​

This is close to the OP scenerio. I'm going to price out 100A.

ice

 

[jaggedben]

This is close to the OP scenerio. I'm going to price out 100A.

You're right, for the person who knows he wants 100A and is willing to pay whatever it takes, there's a simple answer to the question. But what are the chances that he has sticker-shock and you end up doing a load analysis anyway, to determine if 100A is necessary and to try to find a lower price point so that he doesn't give up on the job?

 

[weressl]

You're right, for the person who knows he wants 100A and is willing to pay whatever it takes, there's a simple answer to the question. But what are the chances that he has sticker-shock and you end up doing a load analysis anyway, to determine if 100A is necessary and to try to find a lower price point so that he doesn't give up on the job?

Then the hardwired option would change too. I bet $ to doughnuts that no reasonable load in this range could be offered by a PV, with even a 0$ ROI, unless it is an illuminated stop-sign:lol:.

 

[kwired]

Okay, define "no where near", 50%? 10%?

In any case, I'm sure you are right - the actual load will be less than the requested 100A. I don't know if it is 99A (peak) or 50A (not so peak). So, what number are you going to pick?

Neighbor sees me out working and walks over. "Hey worm, I'm building a shop down on my lower 40. It's about 600 feet to power. I'd like a 100A service. Can you work up a budget price for me?"​

This is close to the OP scenerio. I'm going to price out 100A.

That is when I will find out more about what is desired for load, what may be planned for future and tell owner what options are and what kind of problems he may have if we don't run a certain size of conductors. It is still ultimately up to them to decide what they want to do.

I don't think we have heard what the actual load in the OP consists of. If just a utility shed or something like that, there likely is virtually no load most of the time and when it is used maybe very seldom goes higher than 3000 to 5000 VA. - now a 100 amp conductor may not be so bad for voltage drop, and if VD becomes a problem they may just have to learn they can't run so much at same time if it is not necessary, which many are willing to agree with when you start telling them price of cable needed to minimize voltage drop for a full 100 amps.

 

[jaggedben]

Then the hardwired option would change too.

But not to its advantage, since all the costs are bascially fixed except the conductors themselves.

 

[jaggedben]

Then the hardwired option would change too. I bet $ to doughnuts that no reasonable load in this range could be offered by a PV, with even a 0$ ROI, unless it is an illuminated stop-sign:lol:.

Iceworm seemed to think (in post #20), that the cost of a 600ft feeder installation would be upwards of $16,000.

This system, plus, say, $4000 of batteries, can provide 30A of continuous power, 6000VA of surge power, for just over $13K. That much battery could provide several kWh (which is to say, enough to work with a power tool all evening in a lighted room). Possibly, depending on usage, the number of panels could be less and the overall price lower. If more power is needed in some kind of emergency, a generator could be hooked up.

It is entirely possible that the load that the customer has in mind could be "in this range."

 

[iceworm]

Iceworm seemed to think (in post #20), that the cost of a 600ft feeder installation would be upwards of $16,000. ..."

I re-read post 20 carefully. I didn't list any numbers. You wish to compare to north of $16K for the hardwired version, then attribute the number to you. A number you can attribute to me for a wild rectum guess is south of $10K

A couple of questions:
Is the $13K parts only, or parts and installation?
An emergency generator? Is an emergency like the sun doesn't shine for a day? I suspect the gen is not part of the $13K

Ben -
I'm not against solar. It has it's uses. I've got a system at my cabin (along with a generator if I need any power). I've never seen where they are cost effective (avoiding repitition - see constrainsts listed previously)

ice

 

[ActionDave]

Neighbor sees me out working and walks over. "Hey worm, I'm building a shop down on my lower 40. It's about 600 feet to power. I'd like a 100A service. Can you work up a budget price for me?"​

This is close to the OP scenerio. I'm going to price out 100A.

ice

I'm not pulling six hundred feet of 400MCM for a 100A sub-panel anywhere, any time unless there is a well defined need.

 

[iceworm]

I'm not pulling six hundred feet of 400MCM for a 100A sub-panel anywhere, any time unless there is a well defined need.

Absolutely. Stick to your guns! I definitely agree with you. Of course, for me, a sufficient check would constitute a well defined need.

And then again, I might suggest to the customer a pair of 24KVA, 240/600V xfm and 600' of 3c - #4AL might be a lot cheaper. I might even suggest we do a bit of load planning and see if a pair or 15KVA xfm (60A) is enough. The difference is maybe $1000 - can't spend too many hours on the load planning.

ice