connecting more than one windmill

[Tanqua]

hi all.

been reading this forum for quite a while now and have my first question. i am totally of grid (140km to nearest town) no cell reception, no grid, no nothing, just wind and sun all year, even in the winter.

putting up a high tower is out of the question due to my location, thus i want to know how/can i connect a few smaller mills to achieve a reasonable output. the property is very flat with wide open spaces and no high trees, semi desert area. windspeeds are more or less in the low to med range, occasional high winds.

also will be using solar and a backup generator. am still in the planning stages, would like to do it right from the beginning.

henry

[ghurd]

No problem.
The windmill's rectified output goes to the battery.
So do all the others.
They all do whatever charging they can at the time.

More details here-
http://fieldlines.com/board/index.php/topic,144005.0.html

G-

[Tanqua]

thanx G

[Ungrounded Lightning Rod]

Just be sure you have an adequate dump load and controller to discharge the battery at or above the combined charging rates of all the mills in a high wind (excluding transient gusts).  Otherwise you will overcharge the battery, possibly damaging it, certainly requiring you to water it a LOT more often.

[fabricator]

Seems like in your location solar would put wind to shame, especially in a marginal wind area, you might want to think about just buying a few more solar panels with what you would be spending on wind.

[Tanqua]

solar panels are still quite expensive in south africa. i can build three 10' otherpower PMG's for the price of 800W of solar panels. the wind is blowing for an ave of nine months a year, last month we had winds of 10 to 15 knots most of the time. the lower windspeeds account for more or less a third of the total.

another plus is i dont need high towers, 20' should be ample for my needs. to the north and northwest where the winds are blowing from i guess the closest obstruction to be about 3 to 5 km away, some areas one can see for miles and miles.

[DamonHD]

Certainly a mix of sources (eg at least a little solar in with your wind) is a good idea, to reduce the occasions when you have nothing at all coming in.  It does definitely sound like you should have most of your generation from wind, but don't make it exclusive IMHO.

I have crappy wind resource deep in suburban London (England, rather than Eastern Cape!) only even detectable ~10% of the time or less, but I'm glad to have it chipping in during the winter with pitiful insolation.

Rgds

Damon

[jeraklidis]

No problem.
The windmill's rectified output goes to the battery.
So do all the others.
They all do whatever charging they can at the time.

More details here-
http://fieldlines.com/board/index.php/topic,144005.0.html

G-

I would do the same... I'd run all three phases to your charging area. Then rectify the output and use thick cables to connect in a way that makes sense (in Series voltage is additive and current is the same Parallel voltage is the same and current is additive). Make sure you have a controller that can handle a worst case scenario...

[ghurd]

No problem.
The windmill's rectified output goes to the battery.
So do all the others.
They all do whatever charging they can at the time.

More details here-
http://fieldlines.com/board/index.php/topic,144005.0.html

G-

I would do the same... I'd run all three phases to your charging area. Then rectify the output and use thick cables to connect in a way that makes sense (in Series voltage is additive and current is the same Parallel voltage is the same and current is additive). Make sure you have a controller that can handle a worst case scenario...

I have no idea what you are talking about.  Any way I can read it is not good.

Henry Tanqua should not be confused by that statement.

[ChrisOlson]

I would do the same... I'd run all three phases to your charging area. Then rectify the output and use thick cables to connect in a way that makes sense (in Series voltage is additive and current is the same Parallel voltage is the same and current is additive). Make sure you have a controller that can handle a worst case scenario...

Do what?  I'm not sure what you're saying here.

I run five turbines - three of them on my house.  When you run multiple turbines it's best to rectify at the base of the tower, install an outdoor DC junction box on the wall, and run DC power thru the wall into the building.  That way you only have to make one installation in the house and as you add more more turbines you bury the wiring from the tower to the outside junction box and hook it into the DC bus in the box instead of drilling more holes in the wall.

Rectifying at the tower base requires either a manual shutdown at the tower base (which you should have anyway) or running a signal wire from the panel in the house to relays in the tower base junction for remote shutdown capability.  I'm sure there's other ways to do it, but that's the way I've done it because it's nice to be able to shut down a turbine from inside the house when it's raining cats and dogs outside and the wind is blowing at 60 mph.  Therefore, when you run the DC service thru the wall put enough 12 AWG wires in the conduit, terminated in the outside box on one end, and in the indoor panel on the other end, so you have a separate shutdown signal wire for each turbine you plan to add in the future.  If you plan on running three turbines eventually - put five shutdown signal wires in the conduit.  If you never use two of them, big deal.  Always put in more than you think you need.

You can also run a separate AC service thru the wall for each turbine, if you don't mind drilling more holes in the wall.  But if you have a long wire run from the tower to the house, you get less losses with DC than you do AC.  So regardless, I think rectifying at the tower base is the way to go for a multiple turbine installation that's being used to charge batteries.

Henry mentioned a standby generator.  Keep in mind that if you live off-grid, have a battery bank, turbines, solar, etc., your standby generator should be a battery charging unit, NOT a 120/240 AC unit.  If you use 12 or 24 volt you can build a standby generator out of a small gas engine driving an automotive style alternator like I use:



This thing will put out 30 amps with the engine just idling and will run for three hours on 4-1/2 pints of gas.  If you use 36 or 48 volt you can build an axial turbine generator and drive it with a low rpm engine of some sort for standby power.

If you don't have grid power don't even THINK about buying an inverter/charger - they're the most useless unit on the planet when you don't have grid power.  Using a 120/240 volt standby generator to make AC power to run the charger in the inverter while it powers your house in AC bypass mode is just a way to waste fuel running the generator because generators like that have to run at full bore to make AC power, while a battery charging standby can run at very slow speed.
--
Chris

[scoraigwind]

putting up a high tower is out of the question due to my location,

I wonder why the tower is out of the question?  It would give you a much better result.  You will get a lot of turbulence and problems with ground level turbines.

[Tanqua]

Access and distance is the problem. Have spoken to a few contractors with cranes, quotes are ridicilous. The nearest crane is 240km from me and there are nobody in the area with a large enough truck or tractor to use. Imagine travelling that distance at 30 to 40 km/h.

I was thinking about using old waterpumping windmill stands and then running 6m tubing vertical through the centre and using a winch for lowering and raising. Should be able to reach 30 to 40' in height. Believe me when i tell you the ground is flat, the elevation differs about 5 to 7m over a 3km stretch.

Will post pics when i have figured out how to, any help?

[DamonHD]

For posting help try: http://fieldlines.com/board/index.php/topic,143664.0.html

Rgds

Damon

[fabricator]

Do a search on guyed tilt up towers, no fancy equipment needed and no climbing the tower, ever, a mid size tower can be raised with a hand winch.

[scoraigwind]

Do a search on guyed tilt up towers, no fancy equipment needed and no climbing the tower, ever, a mid size tower can be raised with a hand winch.

Here is a photo of my 20 metre tower with a 3.6 metre diameter turbine on it.  I lowered it in June because the tail had jammed.  I used a 1.6 tonne rope hoist to lower it, and it was pretty easy to do.  It was the first time I took it down since first putting it up in Spring of 2007.  The gin pole is about 7 metres long and there are guys from the gin pole to the tower in 3 places.  The hoist is attached to the end of the gin pole.  I remove the guys from the anchor after attaching the hoist between the anchor and the gin pole.  The anchor is about 20 metres from the tower base.  The gin pole has its own, shorter guys.  When the tower is vertical, the gin pole is sitting a bit above horizontal so that the hoist can apply some tension to the gin pole guys even at the end of the lift.

[scoraigwind]

did it work this time... ?

[scoraigwind]

Here is another photo of a 12 metre mast ready to lift using a single lifting cable that passes over the top of the gin pole in this case.  As the tower goes up the lifting cable parts company from the descending gin pole and pulls direct.  Ultimately it's used as the top guy in this case.

I am struggling a bit to produce pictures with a small enough fiel size that you can actually make out anything useful for some reason.

this is a photo of the previous 20 metre windmill erected.  It's taken from the top of another tower.  YOu can see the trees behind are pretty large so it has to be at least that high.

[scoraigwind]

Finally here is a link to a video I did last year showing some simple guyed towers being lowered and erected by a neighbour, Nigel.
http://www.youtube.com/watch?v=T_VrumkFx4E

and there are a few pages about tilt-up tower design and erection in my Recipe Book, now available in Amazon Kindle format.
http://www.amazon.com/Wind-Turbine-Recipe-Book-ebook/dp/B003XVZADA/

[TomW]

[Boss]

I just love seeing your turbines Hugh,
What kind of material is this tower made from?
Damn beautiful country on your island
Thanks for sharing
Brian

[Tanqua]

Thanks everybody, and for the pics and advice about the tower Hugh. Will def reconcider, maybe just do the tower for the shurflo on a windmill stand to help on cloudy days.

[scoraigwind]

I just love seeing your turbines Hugh,
What kind of material is this tower made from?
Damn beautiful country on your island
Thanks for sharing
Brian

I make towers from ordinary steel pipe.  Or Circular Hollow Section as they call it.  I use 3 inch size (89mm) for the 12 foot turbines (3.6 metre/AWP).  I don't paint it because I found that makes the rusting worse, once it gets going.  Here things rust fast, but I find that steel pipe forms a surface patina of rust, and then this changes very little over long periods of time.  But if it is painted, it forms deep blisters and rusts right through quite fast.  So leaving them bare works best for me.

Yes it is pretty amazingly beautiful here I think, which is why I find it hard to go away.  I will be travelling a lot in the next couple of months including teaching courses in Wales, Ireland, and three for SEI in the USA, but I always look forward to going home too.

[Tanqua]

What is the wall thickness of the pipe/tubing? I would feel "safe" i guess with 4 to 6mm on towers up to 20m or maybe using 4" at the bottom.

[scoraigwind]

Wall thickness would usually be 5.5 mm on those 3 inch pipes.  They do bend and sway a bit, but I am used to that and it doesn't bother me.    Most americans choose the next pipe size up but it's not actually necessary for a 1 kW turbine.

Maximum bending load is usually at the top guy level and not at the base as one would assume.  The guys prevent it bending at the base - especially if you include plenty of guys on the way up.  I usually put in one set of guys per length of pipe i.e. every 6 or 7 metres.  The top ones take all of the real load and that's where the pipe will bend in gusty weather, but so long as the furling works right it will not be damaged.

Hugh

[Tanqua]

I guess since i have not put one up before, and the towers allways looks so thin on photos i'll just have to do it and get it over and done with. I will admit though that i'm not very fond of the idea of all the wasted space around the tower because of the guy-wires as I am planning to put them up as close as safely possible to my house and workshop to keep costs down. I also do know that in order for the turbine to work properly it is of no use putting up a 50cents tower either.

Would it be an option to move them a bit further away then, connect all three together and run a single cable to the batteries?

I am asking this because there would be other structures/sheds/tunnel in the vicinity and I am trying to have the batteries/power room against the house wall and more or less in the centre of things. Hopefully that way I can avoid long cables to a few lights/pumps in the other structures. I should add that I have not started with anything on the property yet, but have bought most of what i need over the last two years. The next step is to gather the goods for the power setup. It is only going to be for 2/3 people to live comfotably and to be selfsustainable.

We do have a supllier in town that sells all sizes/sorts of 3ph cable at better prices that I can source in Cape Town. I have quite a few different sizes and lenghts of cable as well as a number of 6mm/2 rolls of wire by 30m long.

I am aware that there definitely will be power losses in such a system therefore would like to plan well and rather spend money on an extra solar panel than on my own mistakes.

[scoraigwind]

I did help with a system at Temaruru in Zimbabwe that had 4 machines on a hilltop and then they shared a 48 VDC cable to the battery shed.  We had some problems with lightning surges blowing the diodes in the rectifier box up there on the hill but the principle was good.  I don't recommend paralleling them before you convert to DC.  I can't see that working out happily at all.

http://www.scoraigwind.com/powervision/index.htm

Duncan designed them as 'guy wire assisted' free standing towers.   They bolted down onto the rock, and the pipes were pretty massive near the bottom but they put guys on them anyway.  Belt and braces?

Anyway yes you can do a tilt-up free-standing tower.  Why not?  Lots of people do that.  It costs a lot in steel and in foundations but you get rid of the need for guy wires.  Unless you decide to fit them anyway :-)

Hugh

[Tanqua]

Ok, that solves the cabling from the turbines.

Just went to check, I have, added together, 6,8m of dia 220, 165 and 110 by 6mm. Think i will add a lenght of dia 100 and 3 guy wires at the top for a tilt-up, have 6 4m pieces of railway line to concrete and make a pivot from. Sound ok to you?

Am toying with the idea of hydraulicly assisting the tower, number of cylinders lying around from old construction and agricultural machines and my tractor has external hyd connections. Friend has Eng firm with contracts at a mine, can get more large dia pipe off-cutts if I need to.

The other two will be guy-wire towers, and the shurflo will have a windmill stand, just love the look of them. Reminds me of growing up on my grandfathers farm.

Hugh, thank you very much for your time and help in sorting out my tower and cabling issue. Now to source the winches and cables.

Have read on the OP site you had hand in designing the Dans turbines. Is there any difference between theirs and yours worth mentioning? To me they look like basically the same thing. Just a matter of curioucity.

Anyone with suggestions regarding a tilt-up with hyd assistance please feel free to raise your voice. Am open for suggestions.

[scoraigwind]

Hydraulic rams are recently very popular for freestanding towers.

http://www.youtube.com/watch?v=Uro86C2q2no for example.   I woudl say that mostly the installers bring the ram and hydraulic pump with them. 

I still like the old Tirfor rope-hoist.

Differences between the Otherpower design and mine?  They both initially used a too-small disk for the 10 footer.  I rated the turbine for low power at first and then later used a larger disk.  OP upgraded the magnets.  You can go either way, but the larger disk is cheaper and the larger stator is easier to cool.

Otherpower have a nicer looking steel frame but I hope that mine is easier to make.

To be honest I recommend reading both designs and then choosing your own way.  That's what a lot of people seem to do.  And they mostly add their own ideas, which is when it starts to be fun.

Hugh

[Tanqua]

Never mind the reading, I've build both frames this morning, including cutting the material it took me about hour and half max for both. Yours def the easier to make. Must add I have a small eng shop at home with all the tools and machines. I have a passion for series Land Rovers and do a lot of mods to them, have four at the moment.

Rural areas with their lack of sophisticated tooling will def benefit from your simple design. From what Ive seen they normally have some sort of generator, a crude arc welder, hacksaw, gas set and a few other hand tools. The area I'm moving to is one of the most remote areas of SA. Donkey carts are still the main form of transport for the locals. Escom has given grid supply a back seat for another few years. 

I allready have a few people asking  me to build a "wind battery charger" for them. I'm planning a small RE workshop once I'm there. Have had great success with solar stuff before, many thanx to Gary's "built-it solar" site and others. I believe its no use re-inventing the wheel, rather try and make improvements, combine ideas and if possible go the simple route and have an efficient model at the end.


A few photos to give you an idea of the site