Best Size for Residential

[Yianie123.]

I am having a difficult time choosing right size turbine to build.  I know I can look at my application, power consumption and do some math, but is there a good size that is reasonably easy to build, develops real power, and is very durable?  I have read comments that it may be better to have multiple smaller turbines then one larger one.  Any opinions will be greatly appreciated.

[imsmooth]

Actually, you want to have turbine that is as large as possible, rather than multiple smaller ones.  There are three big costs: generator, tower, batteries or grid-tie inverter.  The tower can cost as much or more than the generator.  So if you put up one big turbine you have one cost for the tower.  If you put up two turbine that have half the capacity of the big one, you are still incurring twice the cost for the two towers.

A 10' tower can generatre some appreciable power in the right conditions.  You can get several hundreds of watts.  You can look at my web diary of what I did with the F&P and the Axial turbines.  I have a grid-tie. I built mine mainly to see if I could do it.  There was a lot to learn and this board has been very helpful.  I have a lot of trees, so I am far from developing the true power my turbine is capable of doing.  When I get wind in the right direction I have seen 1000-2000 watts.

Here is the link http://www.mindchallenger.com/wind

[Rover]

I know I can look at my application, power consumption and do some math, but is there a good size that is reasonably easy to build, develops real power, and is very durable? 

Yianie123,

Do the math, figure out what you need , figure out what you need again after a look at conservation. This does not sounds like a hobby for you, so you need to approach it with real numbers.

- Post your numbers
- Don't ignore other forms of RE (Solar)
- When asking for other peoples numbers, see if you can get watt/hours/month  (or even over a year) to be realistic.  I have two 500W turbines, telling someone that is pretty much meaningless . Yeah they "CAN" produce it, but on average? ... err not likely...not even close

I know of very few one solution fits all scenarios in most aspects, I know of even less in wind turbines (otherwise we'd all have one)

[Beaufort]

I agree with the "bigger is better" for everything in wind (swept area, tower, battery bank, etc.) however that's not always a realistic approach due to cost and neighborly concerns over 100 foot towers.  Sometimes we're forced to start smaller and add over time....not easy with wind.  It seems that many here (like myself) have at least two smaller wind turbines in the air for various reasons. The 8' and 10' dia. book models are nice ones.  Some day I'll get up the guts to laminate some real wings and build a 20 footer; I'm convinced that if you can build a 4' or 6' machine and get it to run true, you should have no problem going after the big ones.  The high RPM for the tiny turbines requires very good balancing and good tracking to eliminate the tail wag.  And when stuff breaks, it gets thrown pretty far with the tiny ones. 

[ChrisOlson]

I went with several smaller turbines for the same reason large aircraft have more than one engine - redundancy.  If one goes down I still got power.  Several of us up here in the North Woods who live off-grid have done the same.

I can build two complete 10 foot turbines, ready to put on the tower, for less money than it costs for just the magnets in the generator for a 17 foot.  I can put up three towers for 10 foot machines for less than it costs for one tower for a 17.

And there's survival odds.  We get 80+ mph winds at least once a year, the survival chances for a smaller 10 foot turbine is much better than a large one in high winds.  And if it does go down I can have a replacement on the tower within 2-3 days.

All of this is probably only important to people who live off-grid.  If you live on-grid then a wind turbine is more of a "toy" because you don't rely on it for primary power.  From what I've seen in small wind power, the people who live off-grid almost always put up more than one.  The people who live on-grid or do grid-tie stuff generally seem to think bigger is better.
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Chris

[SparWeb]

Actually, you want to have turbine that is as large as possible, rather than multiple smaller ones.  There are three big costs: generator, tower, batteries or grid-tie inverter.  The tower can cost as much or more than the generator.  So if you put up one big turbine you have one cost for the tower.  If you put up two turbine that have half the capacity of the big one, you are still incurring twice the cost for the two towers.

I can't go along with that advice.  Despite the economic argument about the two towers, the question is being posed about one turbine built as a hobby.  I have built 3 now.  I'm only using one at a time!  As a DIY project the turbine should be best suited to the builder's abilities, interests, and facilities.

Yiannie,
I think I'm one of the ones who steered you away from a "giant" turbine a while ago.  I'm glad you are still keen to have one and looking forward to the project getting under way.  I hope Chris's and Beaufort's disagreements with Mr. Smooth haven't confused you any.  They do layout a lot of the advantages and disadvantages.

If it's any help, I built an 8-foot diameter turbine, and designed the tower to handle up to 12-feet if I ever want it to in the future.  So far the 8 has satisfied my needs, so there's really been no incentive to go much larger.  Instead what I've done is improve upon the art, going from 300 watts peak from the first iteration to my current machine that can kick out a kilowatt at times.

[bj]

    Yannie: you've had a pretty good representation of both sides, with good points on both.  I bought enough neo's to build two ten footers, mostly
because of my lifelong association with Mr. Murphy.  Even with big wind damage, I figure one might survive, and I still be in business.  But that is just me
and my tendency to plan for failure.  Good luck sorting out what is right for you.

[ChrisOlson]

Instead what I've done is improve upon the art, going from 300 watts peak from the first iteration to my current machine that can kick out a kilowatt at times.

I'd also like to point out for Yiannie's sake that the peak power doesn't mean much.  People always talk about their turbines as being 300 watts, 500 watts, 1 kW, whatever.  That's in darn near gale winds.  What's important is how many kWh the thing makes to run your house, or whatever.  It's kWh that gets the work done in your house, NOT the fact that your turbine made 1,000 watts (or whatever) in a storm once.

I have determined over many, many months of logging power output that my 10's make 2.5 kWh per day if the wind averages 12 mph for 12 hours of the day.  My actual output over many, many months is 1.9 kWh per day out of each one.  I get more power out of them in the spring, fall and winter than I do in the summer because the only time the wind really blows here in summer is during a storm.  So for summer, with the long days, solar power is better than wind.  In the winter, when the days are short, wind power beats solar power hands down.

A 10 foot turbine that averages 80 watts output for 24 hours makes that 1.9 kWh output that I have gotten out of mine, averaging the output over about two years.  80 watts from your turbine sounds really weak.  But it adds up and 1.9 kWh is 1.9 kWh no matter if it's made at 80 watts for 24 hours or 1,900 watts for one hour.

And those are real world numbers for a 10 foot turbine, not some hyped-up advertisement for a 10 foot Chinese turbine that claims 2 kW output.  And that's what you really need to know in the end - how many kilowatt-hours do you need.  Figure out how many kWh your house uses in a day, then get some real world numbers from people who have built small and big turbines.  Then decide what would be best for you to generate the power you figure you need or want.
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Chris

[taylorp035]

As Chris Olsen was going with, my example stems from the Bergy 10-kw windmill's in my region.  The one on the lake averages 19% = 1.9 kw = 17,000kwh / year , up to 2000+ kwh per month in the winter and down to 500 kwh per month in the summer.  This is on a 120ft tower, on the lake, in a class 4-5 wind area and a 23ft diameter.  If you are the average person in America, you would need 1000 kwh /  month to power your house.  Obviously (or maybe not), that is a lot of power.  People off the grid use much less power, therefor a few solar panels and 1 or 2 10ft windmills works well.  For some grid tied people like me, it is not financially good decision to put up a windmill.  For myself, generating 35,000kwh's would be near impossible.  I would probably need 10-20kw of solar + a 40-50ft windmill.  Obviously it is cheaper to pay the 10 cents/ kwh.

Good luck with what ever you do, and please run your numbers by the experienced members here before you spend any serious money.

[wooferhound]

You are asking about a Residential area, so my answer would be, as big as you can get away with before you get the attention of the local government.

[ChrisOlson]

If you are the average person in America, you would need 1000 kwh /  month to power your house.

That number amazes me.  My wife and I live pretty good on 10 kWh per day.  On 15 kWh per day we can live a life of lavish luxury.  If we have to, we can get by on 3 kWh in a day.
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Chris

[Yianie123.]

I appreciate everyone's opinion.  I guess it comes down to what can you manage with what you have to work with.  Many smaller 8-10ft blades is most likely good for the one (1) man operation who has limited asistance.  The one (1) large one is likely better if you have assistance and you can get it up in the air.  Either way, you can get the same results by using different methods.  Thanks again eveyone.
John