Thickness and number of windings for 12 or 24 volt 17 foot wind turbines?

[swaro]

Hi,
 I'm new to this forum, and have encountered a problem as you probably know.
 I started to build 17 foot wind turbine. windings are shaped so that 48 volts are obtained. But in Sweden it is very difficult to get the converter that can handle 48 volts. It is almost always converter for 12 volts and 24 volts are available. I was thinking about winding coils so that it was used significantly for 12 or 24 volts.
 To my 48 volts stator, I used 59 turns Using two strands of # 14 AWG wire. But for 12 and 24 volts, I do not know what to use for the thickness of the copper wire and the number of windings.

 Frankly, it is easier to get 12 volt converter than 24 volts converter, but I would appreciate the advantages and disadvantages of each converter.

 My magnetic rotors are adapted to the 17 foot wind turbine, as you might guess,  it's the stator to be changed to be adapted to 12 or 24 volts.

I would appreciate your suggestions

[DanB]

I don't understand really why you should not be able to get 48 volt equipment (inverters etc) worldwide - the shipping cost to sweden is not that bad.  At 12 Volts, in my opinion - a 17 foot wind turbine is too much, the current is way too high, you'll spend more on conductors, rectifiers, charge controllers etc.....

To wind that machine for 12 volts you'd be winding with 8 strands of AWG 14 wire and about 16 turns per coil!  And I expect the parasitic losses in so many parallel turns of wire might be an issue.  (you'd probably do better to wind in Delta)

And for 24 volts, you wind with 4 strands of AWG 14 wire and 30 turns per coil - that can be done (I have done it) but I would advise against it - with a turbine that size you should really just go for 48 Volts.

[fabricator]

I'm running my 17 at 24 volts with Dans original coils, it will make 20 amps at 100 rpms but stalls badly after that, I intend to wind a new stator using 59 turns 12awg one in hand and run it in delta, or possibly star delta switching, this will make a pretty bullet proof 90 ish amp machine.
I personally refuse to pay the long dollars for 48 volt equipment, so I know how you feel.

[DanB]

Hi Fabricator - so are you basically running a 48 volt version of this machine on a 24 volt battery bank?
I could be off here... but if you are keen to go with Delta and 24 volts, I'd probably try fewer turns (about 50?) and you should fit about 2 strands of AWG 13 wire in there (about the same at 10 gauge).  I've made a couple for 24 volts in star (wye) and they worked fine, but so many parallel connections and so many little ends to strip... going delta at that low voltage might make sense.

That said - I really don't see why you think 48V is so expensive compared to 24.  seems cheaper to me - seems like inverters, charge controllers etc cost the same.  But at 24V you have problems with parallel battery connections (not the best arrangement) - conductors that need to be 4x larger (you need to buy 4x more copper for the whole system), you need double the rectifiers.... your charge controller needs to handle twice the current (about 120 amps).  For me...   once you get into something like a 17' turbine then a 48V system seems to make good economic sense.

People use 48 Volts for larger systems because they are less expensive, and more efficient than lower voltage systems.  But...  if you already have significant investment in a sizable system that's lower voltage, then perhaps compromises make sense.  I have neighbors who setup 12 volt systems years ago and they've grown... quite large, now they're sort of 'stuck' there.  It gets messy though.

I was at 12 Volts here until I built my first 17' machine - and decided to change everything (which involved removing all the 12 volt lights/pumps/etc ~ new inverter, charge controllers, re-wiring solar panels and giving away a few solar panels) at that time.  Glad I did... it's saved me lots of grief since then I expect.

[swaro]

Hi DanB,
One difference that we have in Sweden compared to the U.S. is that we have 230 volts in our collection, I guess in the U.S. use to 110 volts. that way, I am locked to order these kinds of products from the U.S., not because I have found a good supplier, I have tried to find suppliers but the price is too high and fall outside my budget. But if you know any supplier may be suitable, so you can share your experiences.

Inverter pure sine 3000W, 48V in Sweden will cost 2125 U.S. dollars. Now I do not know what the U.S. price, but do you think the price is reasonable for this product? It seems that the price is a bit too high, that's what my first feeling says.
price of 24 volts 3000W is 375 U.S. dollars. You see the reason for my concern.


Hi fabricator,
It is sad that we have the same problem, but good that you have experience in the same situation.
Have you had time to try if it works fine with 59 turns 12awg one in hand and run it in delta?
Or what about DanB suggests, "I'd Probably try fewer turns (about 50?) and You Should fit about 2 strands of AWG 13 wire in there (about the Sami at 10 gauge)" run it in Delta?

[smidy]

hello swaro
I dont know if you know about www.24volt.eu? they have inverters in volts from 12-48, and I think they arent too expensive for sinevaveinverters, ex 3000W 48V  16.900,00kr

[Flux]

I agree with Dan that 12v is not practical for 17ft.

For 24v I suspect the simplast option is to split the stator into 2 star connected sections, run 6 wires down the tower and use two rectifiers in parallel on the dc side, each one fed from the half sections.

If you understand the difference between 3 phase and 6 phase you could reverse the p[hasing of one half and make it 6 phase by joining the star points. It may match a bit better 6 phase but if you open the link between the two star popints then it comes back to two 3 phase windings paralleled via rectifiers.

Try delta if you want but i gave up with it long ago, if you must go with the

[Flux]

I haven't a clue what happened there but it posted itself when I was part way through typing.

Continuing from where it screwed up :- if you must go with parallel connection I would use the number of turns for delta but connected IRP ( jerry). You still need 6 leads down the tower unless you put the rectifier at the top,. I see no snag with the extra wires as you would need 3 thicker ones for a single 3 phase winding and thew 6 smaller ones will be more flexible at the size involved.

I think 24v is just about practical at this size, I wouldn't even try it at 12v unless you are prepared to accept a large dearting on the potential full load output power. You would gain from the larger swept area in low winds but you would need to furl very early to limit the top end power otherwise the cables and rectifiers would be a nightmare..

Flux

[fabricator]

Dan, I don't want to wind multiple strands on this stator, it's pretty much impossible to make good tight coils with multiple strands, when you go to 24 volt there are simply so many more options with charge controllers and inverters, you are not stuck with the big names. You can buy industrial quality inverters like AIMS and Samlex, without the thousand dollars added just for the name on a big name inverter.
I have a 60 dollar coleman air charge controller that is fully settable and a 250 dollar AIMS 2.5k/5k inverter to power a 120 volt element in my hydronic heating system for a dump load, for a 48 volt battery charging system with a big name inverter you got about three options, here are a couple pictures of how I'm avoiding huge conductors.

[fabricator]

Here are the batteries, the buss box and the charge controller and dump inverter.

[dnix71]

He isn't kidding about 48v inverters being expensive. The 3kw Outback EU export version is $2k US

http://www.ecodirect.com/OutBack-VFX3048E-3000-Watts-48-Volts-p/outback-vfx3048e.htm

The Xantrex 4500 watt 50Hz inverter is $3500  http://www.solarhome.org/browseproducts/Xantrex-SW4548E-48V-230-VAC-50-HZ-4500VA-Inverter.HTML

[fabricator]

Not only are the expensive, for the most part they aren't big enough, so then what, but two of the damned things?

[DanB]

A few unrelated comments here...

Chris O. has argued, and made a good video about the merits of Delta vs Star (wye) winding.  I do believe, and have noticed that when I wire in Delta, there is usually some very slight noticeable drag on the alternator - there has to be parasitic currents in delta, unless the machine is built *perfectly* - however, I usually find it to be small, and when winding in Star, with multiple strands, I find the same problem comes up.  There are parasitic currents within the multiple strands in each coil.  I expect one can wind either way and in the end it'll likely come out the same.  I prefer the series(star) connection in most cases - but for low voltage machines Delta might make sense.  I've made a few alternators lately where I bring out all 6 leads and I don't notice much difference in drag between star, or delta.  So for 24 Volts - I would probably lean towards a delta connection before I bothered to bring 6 leads down the tower... however I'm not sure why bringing 6 leads down bothers me so much... (but it does).

Again - a 17' turbine is just too big for a 12 Volt system, I won't say its impossible but it's going to be a real pain to build and the conductors/diodes and regulation are going to cost an arm and a leg.

Inverter cost....yes, $2000ish is a lot of cabbage so to speak.  But ~ that is what a 'good inverter' costs.  The difference between a $300 inverter and a $2000 inverter is night and day in my opinion.  The $2000 unit will likely include a lot of features that the cheap one doesn't.   The $2000 inverter will likely weigh about 100 pounds, the $300 one will weigh about 10 (and there is a good reason for that).  It will likely also be a very good battery charger.  It will have a large/heavy transformer that can take serious surges for a period of time (for starting big motors and stuff).  It will be wired such that it can be legally hooked into a breaker box with proper grounding/etc (lots of the inexpensive ones are not).  It depends what you want here - generally cheap inverters are built for RV's, tractor trailers, small hunting cabins etc.  If it's to be a 'house' with normal appliances and wired to code, then $2000 for an inverter (or $4000 for two of them if you need 240V and more power)doesn't seem so bad in my opinion.  The inverter is a really important part of the system ~ when you consider all the other costs in the system (tower, batteries, controllers, meters, copper, solar panels, wind turbine, backup generator etc) - then the cost of the inverter, even if it is a couple/few grand is really a small part of it.

[ChrisOlson]

Chris O. has argued, and made a good video about the merits of Delta vs Star (wye) winding.  I do believe, and have noticed that when I wire in Delta, there is usually some very slight noticeable drag on the alternator - there has to be parasitic currents in delta, unless the machine is built *perfectly* - however, I usually find it to be small, and when winding in Star, with multiple strands, I find the same problem comes up

I think a 12 volt 17 footer would be doable.  But even with my latest 12 foot geared turbine, which is more powerful than my 13 footer, I have to use dual 8/3 cables down the tower, and 2/0 copper underground to handle the amps on 12 volt.  That turbine has averaged 4.33 kWh per day on 12 volt since I built it, and I think we only had two days with any real decent wind.  So I don't consider that too bad.

For most people the wind blows at 12 mph about 100x more than it does at 20 or above.  If you have a 12 volt system and wanted to put up a 17 foot 12 volt turbine, it would make tremendous power in the average wind speeds that most people get, which is what really counts day in and day out.  You'd just have to furl it at a reasonable output level like I'm doing with my geared 12 - right around 1.2 kW, or about 80 amps.  I've pushed 120-130 amps with my 12 volt turbines but it's not practical to do that, no matter what the voltage is, because those high charging rates on a battery bank push the current beyond what the batteries can absorb and all it does is dump power.

If you have a 12 volt system I'm pretty sure it's cheaper to build a couple 10's or 12's than it is a single 17, and that's the way I'd go.

As far as the argument on 12 vs 24 vs 48, I love the 12 volt system.  I had 48 once and switched back to 12 because any time I wanted to expand the system I ran up against a wall of cost on 48 volt.  12 VDC systems are the most common on earth because of the automotive industry, and there's a lot of quality stuff built for 12 volt automotive that adapts well to 12 volt off-grid power systems.  If you want to put in DC appliances or lighting in your house, just get stuff built for RV's.  You want a small standby battery charger - you can grab a car alternator out of the junkyard, drive it with a small gas engine and charge your battery bank for hours on a quart of gas.  You can get 3-5 kW inverters for 12 volt, that are designed to wire into panels in RV's and boats with a ground bonded neutral, and will take anything you can throw at them, for less than $500.

All brands like Outback and Xantrex have is the name and cost, and a bunch of menus and options on a screen that you don't need for off-grid power unless you like to tinker with your inverter.  The less than $500 12 volt inverters that I got now are so dead reliable that I haven't even looked at one for two months.  They "just work" and when I throw the light switch in the house I know the lights are going to come on.

So that's my take on it - 12 volt, the most economical to install, maintain and repair there is.  24 volt, maybe slightly better efficiency from your wind turbines, but not much, less selection available for quality inverters, more expensive to maintain, repair and expand.  48 volt - no way.  BTDT and neither me nor my checkbook liked it.
--
Chris

[swaro]

Hi Smidy,
I have knowledge of the home page, it was also where I got price example. I've looked at a number of other sites with similar stuff but found nothing that makes me happy. I have also searched the international sides, but the price seems about the same level.

 I think I got good information from here, now I know at least how I'm going to take me on. therefore, I would like to thank everyone who contributed information.

[DanB]

Chris O. has argued, and made a good video about the merits of Delta vs Star (wye) winding.  I do believe, and have noticed that when I wire in Delta, there is usually some very slight noticeable drag on the alternator - there has to be parasitic currents in delta, unless the machine is built *perfectly* - however, I usually find it to be small, and when winding in Star, with multiple strands, I find the same problem comes up

I think a 12 volt 17 footer would be doable.  But even with my latest 12 foot geared turbine, which is more powerful than my 13 footer, I have to use dual 8/3 cables down the tower, and 2/0 copper underground to handle the amps on 12 volt.  That turbine has averaged 4.33 kWh per day on 12 volt since I built it, and I think we only had two days with any real decent wind.  So I don't consider that too bad.

For most people the wind blows at 12 mph about 100x more than it does at 20 or above.  If you have a 12 volt system and wanted to put up a 17 foot 12 volt turbine, it would make tremendous power in the average wind speeds that most people get, which is what really counts day in and day out.  You'd just have to furl it at a reasonable output level like I'm doing with my geared 12 - right around 1.2 kW, or about 80 amps.  I've pushed 120-130 amps with my 12 volt turbines but it's not practical to do that, no matter what the voltage is, because those high charging rates on a battery bank push the current beyond what the batteries can absorb and all it does is dump power.

If you have a 12 volt system I'm pretty sure it's cheaper to build a couple 10's or 12's than it is a single 17, and that's the way I'd go.

As far as the argument on 12 vs 24 vs 48, I love the 12 volt system.  I had 48 once and switched back to 12 because any time I wanted to expand the system I ran up against a wall of cost on 48 volt.  12 VDC systems are the most common on earth because of the automotive industry, and there's a lot of quality stuff built for 12 volt automotive that adapts well to 12 volt off-grid power systems.  If you want to put in DC appliances or lighting in your house, just get stuff built for RV's.  You want a small standby battery charger - you can grab a car alternator out of the junkyard, drive it with a small gas engine and charge your battery bank for hours on a quart of gas.  You can get 3-5 kW inverters for 12 volt, that are designed to wire into panels in RV's and boats with a ground bonded neutral, and will take anything you can throw at them, for less than $500.

All brands like Outback and Xantrex have is the name and cost, and a bunch of menus and options on a screen that you don't need for off-grid power unless you like to tinker with your inverter.  The less than $500 12 volt inverters that I got now are so dead reliable that I haven't even looked at one for two months.  They "just work" and when I throw the light switch in the house I know the lights are going to come on.

So that's my take on it - 12 volt, the most economical to install, maintain and repair there is.  24 volt, maybe slightly better efficiency from your wind turbines, but not much, less selection available for quality inverters, more expensive to maintain, repair and expand.  48 volt - no way.  BTDT and neither me nor my checkbook liked it.
--
Chris

More later.  I should just say Chris... try living 'off grid' -with a fridge, washing machine, welder, a couple microwaves... maybe a well pump... 
there is a reason that 48V is the standard now.  It's more efficient, and less expensive.  I was on 12V with 'automotive appliances' for the first 35 years or so of my life.  I have neighbors that are still stuck with clunky 12V systems and they are only hoping for the day that they can afford to get out of it.  12V is nice if you have a hunting cabin or an RV or perhaps you live in a 3rd world situation and your only needs are lights and a radio.  Otherwise it's just poor use of resources.  I went from 12 to 48 the day I put up my first 17' machine - not because I am made of money (I am not) - only because it saved a lot of money and trouble.  It took a small investment to do so and now I have no regrets.

I expect Chris does not live off grid and if it's just a hobby then...  12 Volts probably seems fine.  For me, at the moment... my 20' turbine (it is windy at the moment) is peaking over 100 amps (that'd be 400 amps at 12 volts), it's cloudy... so my solar isn't doing much...  I have more energy than I know what to do with today.

Another note... cheap inverters -they do work fine for most stuff.  I would not expect one to run a well pump or take the surge when you start a motor while something else is running.  If its not a true sine wave unit.. it may or may not melt your cordless drill charger.... Until you need to start a big motor - or have some sort of surge in the system... it might work fine.  It's fine to get a 3000 Watt $300 inverter and it will do fine in most cases.  It wont charge your battery from a generator (the more expensive unit will do a nice job there).  Those $2000 'inverters' are really lots more than just inverters  - in a 'hobby' situation you may not realize the difference but if its the stuff you depend on then you will.

[DanB]

All brands like Outback and Xantrex have is the name and cost, and a bunch of menus and options on a screen that you don't need for off-grid power unless you like to tinker with your inverter.

Right...  exactly!~
they are slightly full of bells and whistles it seems... but have you actually tried to live off grid with batteries and an inverter, and a washing machine, well pump, welders... etc?  What if you need to charge your batteries from a generator or something...  (at a serious rate, say maybe 100 amps or so... properly tapered etc...  )

My inverter also has 3 aux relays to play with that can turn stuff on and off at different voltages, I can set the hysteresis  (I use that for some charge control)

It can also start my generator to charge my batteries automatically if I want it to (if my generator had electric start which it doesnt....)

I have it hooked up through a transformer so I have 240VAC (with one inverter) to run my welder and my well pump as needed.

In my mind, the bottom line is this...
inverters.. you will get what you pay for.
12, 24 or 48 Volts...  yes, 12, or 24 is easier to expand (a bit less money can add batteries or solar panels).  48 Volts is going to save you tons everywhere else ~ if ~ (and perhaps only if) you want a serious power system, capable of running all the stuff most folks in america and europe are used to running.

Again... in a small cabin or RV... 3rd world country, or hobby system - 12 Volts might still make sense for a few years just because of the automotive industry and the availability of small 12 volt appliances and cheap modified sine wave inverters.

[ChrisOlson]

If its not a true sine wave unit.. it may or may not melt your cordless drill charger.... Until you need to start a big motor - or have some sort of surge in the system... it might work fine.  It's fine to get a 3000 Watt $300 inverter and it will do fine in most cases.  It wont charge your battery from a generator (the more expensive unit will do a nice job there).

DanB, you're pretty far off the mark here.  In fact, you didn't even hit the target after three shots.

Everything in my house is powered by two 3KW AIMS Power PWRIC300012W inverters.  They have built-in smart battery chargers, auto transfer switches, ground bonded neutral, the whole nine yards.  They run any motor I got, including air compressor, water pump, bench grinders, drill press, hand tools, furnace blower, they are modified sine and run microwave ovens without the transformer buzzing, and the 'fridge pulls the identical .9 amps on inverter power that it pulls on generator power.

 $449 each with 3 year warranty from one of the biggest names in recreational , marine and industrial inverters on earth.  AIMS Power just starting building units for off-grid, standby and prime residential power with the above features.  They are top-of-the-line inverters at a fraction of what you'll pay for any 48 volt unit.

As far as 12 volt and off-grid, perhaps I'm "Third World" to your fancy 48 volt system.  But my 12 volt system is more efficient than the XW6048 inverter I had before.  That XW6048 had split-phase and with the legs of the split phase loaded unevenly (which is going to happen in ANY 240 volt panel) the efficiency was horrible.  We no longer have 240 split phase in our house  - everything is 120 volt.  For 240 volt stuff like the welder I run the generator.

So you can refer to my system as "clunky" or "hobby" if you want, but it powers our house, and my wife and I live pretty good on 9-10 kWh per day.  And we also have washing machine, microwave, real 'fridge and freezer - the whole nine yards - all totally powered by sun, wind and occasional gas charger or generator power - all on 12 volts.  The difference between mine and what you've seen is that I know how to design a system that works.
--
Chris

[DanB]

If its not a true sine wave unit.. it may or may not melt your cordless drill charger.... Until you need to start a big motor - or have some sort of surge in the system... it might work fine.  It's fine to get a 3000 Watt $300 inverter and it will do fine in most cases.  It wont charge your battery from a generator (the more expensive unit will do a nice job there).

DanB, you're pretty far off the mark here.  In fact, you didn't even hit the target after three shots.

Everything in my house is powered by two 3KW AIMS Power PWRIC300012W inverters.  They have built-in smart battery chargers, auto transfer switches, ground bonded neutral, the whole nine yards.  They run any motor I got, including air compressor, water pump, bench grinders, drill press, hand tools, furnace blower, they are modified sine and run microwave ovens without the transformer buzzing, and the 'fridge pulls the identical .9 amps on inverter power that it pulls on generator power.

 $449 each with 3 year warranty from one of the biggest names in recreational , marine and industrial inverters on earth.  AIMS Power just starting building units for off-grid, standby and prime residential power with the above features.  They are top-of-the-line inverters at a fraction of what you'll pay for any 48 volt unit.

As far as 12 volt and off-grid, perhaps I'm "Third World" to your fancy 48 volt system.  But my 12 volt system is more efficient than the XW6048 inverter I had before.  That XW6048 had split-phase and with the legs of the split phase loaded unevenly (which is going to happen in ANY 240 volt panel) the efficiency was horrible.  We no longer have 240 split phase in our house  - everything is 120 volt.  For 240 volt stuff like the welder I run the generator.

So you can refer to my system as "clunky" or "hobby" if you want, but it powers our house, and my wife and I live pretty good on 9-10 kWh per day.  And we also have washing machine, microwave, real 'fridge and freezer - the whole nine yards - all totally powered by sun, wind and occasional gas charger or generator power - all on 12 volts.  The difference between mine and what you've seen is that I know how to design a system that works.
--
Chris

Hi Chris - well I was wrong once before that I remember so it's possible that it could happen again! ;-)
Do you have a link to the inverter you use?, I'm curious....
at any rate, if you're using 12V you need about 16 x more copper(except that in the stator of your wind turbine which should remain the same) than you do at 48, and 4x the rectifier and 4x the regulator/dump load.
It does sound then like you actually do live 'off grid'.  I can't hardly imagine doing what I do here at 12 Volts but I do know it's possible.  To me though, it just does not make sense... it'd be like having a 2 volt battery in your car. 
The inverter I use here is 4000 Watts, I only have 1- got it perhaps 6 or 7 years ago refurbished for about $1800.  Being only 4000 Watts I still have to be a bit careful about what's running and when... but it does handle surges nicely.  It's an old trace SW4048.

I find myself usually 'stuck in the past'... but in this case, I find it hard to believe that if one is designing a system to run a normal household it makes sense to go with 'lower voltage'.  The standard now, for battery systems is 48 Volts - its simply more efficient and the cost of energy will be less at the end of the day.  I realized that really fast when I went to install my first larger 17' machine.  I removed all my 12V lighting... 12V appliances... etc, and installed a 48 volt inverter *and* got a spare backup inverter (only 1000 watts) juist incase something went wrong with the bigger one.

Its really quite a no brainer in my opinion,.

a 48 Volt system requires....
1/16 of the copper as a 12V system
1/4 of the diodes if you need to rectify anything.
At 12 Volts... losses in the rectifiers are about 10%, more like 2.5 at 48, which is significant... and lets not bother to talk about the size of heat sinks required or... fans required to remove heat from your rectifiers.
1/4 of the current rating of your controller
Batteries are likely to be in series rather than parallel which has obvious advantages

Again though - there are drawbacks to 48 Volts...
I can no longer use 12 volt stuff easily.  I have a power supply for my HAM radio...
no more 12 Volt lights or 12 V car stereos...
if I want to be *really reliable* - if my inverter fails....  I need either a backup generator or a spare inverter.  (I do have both)

The difference between mine and what you've seen is that I know how to design a system that works.

Sorry don't buy that... you pobably do know how to design a system that works, no doubt.  So did I, and most of my neighbors.  Some of my neighbors are still stuck with clunky 12V systems that work...  nicely I might add, but... had they to do it all over again they'd never go there again.  Again Chris - unless it is a:
- small remote cabin for weekends or hunting
- RV
- Tractor trailer sort of truck or something
- 3rd world country
then designing a system for 12 Volts makes no sense.  The standard these days is at least 24 and for the most part 48 Volts, if it is to be a battery based system - and there are *lots* of good reasons for that.  Do you insist on reinventing everything from the ground up?  If so, someday you will likely come to the same conclusion ;-)

[rossw]

If its not a true sine wave unit.. it may or may not melt your cordless drill charger.... Until you need to start a big motor - or have some sort of surge in the system... it might work fine.  It's fine to get a 3000 Watt $300 inverter and it will do fine in most cases.  It wont charge your battery from a generator (the more expensive unit will do a nice job there).

DanB, you're pretty far off the mark here.  In fact, you didn't even hit the target after three shots.

Funny, I thought *HE* was spot on the money, and *YOU* were the one way off the mark.

Everything in my house is powered by two 3KW ...... (list of bells and whistles deleted) modified sine and (justifications deleted)

Just because a couple of dinky toys happen to run the loads YOU have doesn't make it THE correct answer for others.

top-of-the-line inverters at a fraction of what you'll pay for any 48 volt unit.

Ahh, so 12V/cheap is good, 48V bad. I see where you're comming from now. Pity you don't share the same "reality" the rest of us have to.

As far as 12 volt and off-grid, perhaps I'm "Third World" to your fancy 48 volt system.

48V systems are hardly "fancy". For any non-trivial power, they're virtually essential IMO.

But my 12 volt system is more efficient than the XW6048 inverter I had before.  That XW6048 had split-phase and with the legs of the split phase loaded unevenly (which is going to happen in ANY 240 volt panel) the efficiency was horrible.  We no longer have 240 split phase in our house  - everything is 120 volt.  For 240 volt stuff like the welder I run the generator.

Soooo... you blame 48V for YOUR inability to use your resources efficiently?  Yeah, right, I can see how that's the 48V systems fault.

So you can refer to my system as "clunky" or "hobby" if you want, but it powers our house, and my wife and I live pretty good on 9-10 kWh per day.  And we also have washing machine, microwave, real 'fridge and freezer - the whole nine yards - all totally powered by sun, wind and occasional gas charger or generator power - all on 12 volts.  The difference between mine and what you've seen is that I know how to design a system that works.

My wife and I, and our late-teenage daughter also "live pretty good" with the same washing machine, dishwasher, microwave, real fridge, hairdriers etc. And the plasma TV, and the plethora of computers, and the lathes and grinders and the welder and bore pump and pressure pump and the plethora of other devices. Similarly running off PV, wind and the occasional top-up from a propane genset when weather is uncooperative.

I can't imagine trying to do all this with quasi-wave, or off 12V.

You can protest all you like, but 12V simply IS NOT SUITABLE for a sizable installation you want to work, work well, and keep working for years. The extra "crap" on some of these better units  are *SO* worth the effort... let me give you an example from my next door neighbour who was moaning and bitching about his last week...

He went 120V!!  He spent a small fortune on batteries (60 of them at 900 amphours each) - and an expensive genset - but he cut corners on the inverter.
Every time the system transfers to generator his computers reboot, his security system resets, his security cameras all reset to factory defaults, his TV turns off etc.

My "expensive" inverter will call for the genset when it needs it (power draw too high, battery volts too low, too many amphours drawn by 7pm etc etc - great list of conditions it can start the genset) - it'll then watch for the generator to come online. When it does it matches generator volts, frequency and phase, then "jumpers" the generator directly to the load and inverter - and then SLOWLY transfers the load to the generator. No switching spikes, generator doesn't just instantly have to take the load (and all the nastyness that causes).

Un-necessary whistles and bells, expensive crap? I think not.  Sure, the technology probably exists to do it for 12V too - but the currents involved for similar sized inverters are just insane. Silicon losses, cable losses and battery load make 12V UNSUITABLE for that size system IMO.

[Madscientist267]

DanB -

Stupid question, and probably a bad moment to interject, especially with argument...

You mention running batteries in series as being better than running them in parallel...

Granted, I'm not off grid, and ATM it is more of a hobby (although not for much longer hopefully...)

I go out of my way when possible to try and ensure that I don't leave cells 'stranded' in single series strings.

I'll agree that the higher voltage systems are more efficient for numerous reasons, but I don't think that even if I had plans for a 48V system that I would ever go ahead and build it unless I could bridge after each battery in the string to a twin in a parallel string. I know that this literally doubles the cost, but IMO it would be better to run a bank of twice as many smaller batteries than a bank of 1 single long string.

Too many times, parallel batteries have saved me from destroying either one due to deep discharge, etc. They help 'support' each other electrically so that neither one gets even more damaged from cell reversal, etc.

Got a set of 4 of them actually that I'm convinced this is their longevity, just wish they were higher capacity to start with - 4x 12V 12AH SLA that I've had for 15 years and they're still @ something like 75% of their capacity - and I beat the $#!+ out of them.

Not saying you don't have a good reason, but it seems from the wording that you're eluding to paralleling as a bad thing... ?

Steve

[fabricator]

Here is one of the aims units I use, dinky toy? NOT, made in Japan not China, I always thought this site was about options, now it appears if you don't have the biggest most high priced inverter your the "Village idiot" this surely seems like conduct unbefitting a "Global Moderator" and is very disapointing.
http://www.theinverterstore.com/the-inverter-store-product.php?model=pwrinv5k-front-rgb

[ChrisOlson]

then designing a system for 12 Volts makes no sense.  The standard these days is at least 24 and for the most part 48 Volts, if it is to be a battery based system - and there are *lots* of good reasons for that.  Do you insist on reinventing everything from the ground up?

You dang right I re-invent everything from the ground up.  I've spent most of my life doing just that, and correcting the mistakes made in past designs.

I'll tell you without blinking an eye that my cost per kWh in equipment and maintenance is less than yours.  Granted, we don't use a lot of kWh because we wait to wash clothes some days when the wind is blowing and the sun is shining good.  We heat our house with coal and our furnace is hand fired and the blower only draws 85 watts.  We don't have things like AC for summer time but our house is only 900 square feet and doesn't take much to cool or heat it.  We don't watch regular TV much - we got a thing for our laptops so we can watch TV on those because they only draw 65 watts instead of 400 for a TV.  Our freezer is small and will only hold a half a hog or quarter of beef, or two deer, but it's big enough for us.  We have a combination of 12 volt florescent lighting and 120 volt CF lighting - also in my workshop I don't use 120 volt florescent tube lights because they aren't very efficient compared to CF or 12 volt florescent tube lights.  We got a timer on our 'fridge so it only runs during the day when the sun is shining, but it makes it thru the night fine.  And there's many other things - we don't live like "normal" people probably, but we're far from "third world", at least in my mind.

As far as not making sense, somebody tired to tell me that geared drives on small wind turbines don't make any sense either.  They're wrong.  I'm a mechanical engineer by education, although I farm these days.  You never tell an engineer with a passion for re-inventing things from the ground up that something won't work or doesn't make sense because he'll prove you wrong every time.  And at the end of the day when everything is said and done, copper wire is way cheaper than inverters, and a well-designed geared drive on a wind turbine is way cheaper than big expensive neo magnets.

After averaging many readings taken at different times I've determined that my new geared 12 foot (12 volt, BTW) turbine puts out 319 watts @ 12 mph wind speed with the rotor supplying roughly 360 watts to the shaft.  Right around 87% efficient @ 12 mph from the input shaft to the batteries.  You'll be hard pressed to match that with any 48 volt direct drive, and that 12 mph figure was what was important to me in that design because that's our average wind speed here.  I don't care what it puts out 20 or 25 mph, although it does peg the ammeter quite regularly in higher winds.

And I also invented a different way to "dump" power with a load increasing system on my inverters to heat water with 120 volt inverter power instead of using DC because the losses are less in the inverter than they are even transmitting 48 volt DC power to heaters.  But that's another story.  The bottom line is, don't try to tell me that a 48 volt system is "more efficient" as a generalization, just because it takes smaller copper, because I'll prove you wrong.  The bottom line, when everything is said and done, is the cost per kWh in equipment, maintenance and repairs on the system spread out over several years, and that includes eventual battery replacement and recycling of your old batteries.

I've kept immaculate records on everything I've done and I estimate my cost at battery replacement time to be 14.7 cents per kWh spread out over 10 years on my 12 volt system, using today's prices and adjusting for 2% increase in the cost of batteries, per year, after 10 years.  The cost of grid power is around 10.5 cents, so I still can't compete with the cost of grid power today.  But in 10 years I'll bet I can.  What's your figures on your 48 volt system?
--
Chris

[DanG]

Oh sure, its all fun and games until some gets their eye-verter poked by a post!

I've religiously bought 48V large inverters for buildings and 12V for mobile units... and now find I needed 24V to mesh up to military and HD OTR truck components. And I thought I was being smart by not buying the 'wrong' inverter to begin with.

Chris, sorry you bought the wrong big inverter and glad you accommodated the 12V ones but blanket statements that 12V is the only path to an enlightened RE happening...  ...just aint so.

[ChrisOlson]

Here is one of the aims units I use, dinky toy? NOT, made in Japan not China, I alway thought this site was about options, now it appears if you don't have the biggest most hig priced inverter your the "Village idiot" this surely seems like conduct unbefitting a "Global Moderator" and is very disapointing.

I agree.  There's more than one way to skin a cat.  For those who think there isn't, you're in for a rude awakening.

I'm done here.
--
Chris

[Madscientist267]

Hello? Is this thing on?

<hears squeals...>

 

Steve

[fabricator]

Oh sure, its all fun and games until some gets their eye-verter poked by a post!

I've religiously bought 48V large inverters for buildings and 12V for mobile units... and now find I needed 24V to mesh up to military and HD OTR truck components. And I thought I was being smart by not buying the 'wrong' inverter to begin with.

Chris, sorry you bought the wrong big inverter and glad you accommodated the 12V ones but blanket statements that 12V is the only path to an enlightened RE happening...  ...just aint so.

Wouldn't you also agree that for every individual, in every situation, that 48 volt inverters for buildings could also be characterized as a blanket statement that just aint so?

[fabricator]

Hello? Is this thing on?

<hears squeals...>

 

Steve

Turn down the gain and that feed back will quiet down.

[Madscientist267]

Jeez guys...

First of all, designing, fabricating, and installing an entire system to run an entire house off of (you guessed it) entirely RE is an accomplishment that obviously takes nothing short of a lot of knowledge, experience, time, and of course, money. For most of the people on here, it is still just a dream...

And you guys are pi$$ing at each other over voltage?!?!

I don't get it...

Steve

[DanG]

Wouldn't you also agree that for every individual, in every situation, that 48 volt inverters for buildings could also be characterized as a blanket statement that just aint so?

fabricator

Indeed.

[fabricator]

Ok, now I really believe an apology is in order from Ross for the village idiot post, that kind of conduct by a moderator is certainly uncalled for.

[TomW]

Guys n Gals;

If I knew how to I would split this thread off to preserve the original question which seems to have gotten lost. Maybe its me that is lost?

I am in the middle @24 Volts but don't have any intention of joining in the voltage wars.

I will make a blanket statement, however:

Blanket Statements are a bad thing [TM]

 

Tom

[freejuice]

FWIW,
 I have an AIMS inverter, 48v 7000 watt. The thing listed for about 1800 dollars, I found one never used on Ebay, paid much less than 1800. It is now grid tied to a transfer switch and works very well.no problems at all...nice well made units
 
There is good arguments on both side of the fence for 12, 24 & 48.
 But too each his or her own. I wont call anyone out over an inverter.... Chris dosent beat up on me for my choice and I dont beat up on him...live and let live.

 My personal observation: 48v is expensive and limited choices
24v not so bad, more choices, cost not as bad but can still be pricey
12v a bunch of choices

 But to be quite honest with everyone.....and if I lived off grid where I could be away from everything for a month or so  due to bad winter weather I would start off with 48 v, I would also have a 24 volt inverter and a 12 volt inverter inside a closet, in case a few batteries crapped out, or an inverter died.

 I "got's" to have my "inter-net's"
 Sorry for "off threading"