Small wind turbines no longer worth it?

[12VoltInstalls]

Wind, power is proportional to cube of speed, so we need "Cubed ... Mean ... CubeRoot"

I’m going to start using that as my new pet euphemism to name-call bozos and boneheads: “cuberoot”

 

[HighDesertOffgrid]

...At $150 price of entry, though, it could be ‘cheap’ investment for some charge overnight.

What is the model/brand and how does it brake in high wind (or if there is no load because batteries are full or strong sun is out).

I’m just curious. In the right place wind could be a benefit, but if 5mph is only 10W at 15V generation that would be a typical “no it’s not worth it” scenario.

ROI $ is not as clear cut as a simple wattage calculation for me. As the majority of my winds are after sundown, lessening cycle depth plays some part on battery life. I don't have any with/without wind assistance longevity data, but I know it helps some.
As heat is the enemy of electronics, taking some load from my charge controllers during the day helps to a smaller degree as well.

Model:


For braking, I have an a/c electric water heater programed as a dump load for excess solar and wind. It gradually increases current to the water heater element starting @ 27.5V and ramping up to 100% of 2000 watts at 28V. This, along with standard ac loads, has been effective.
Right now it is producing 28 watts at at 27.5V at 3mph wind speed according to my clamp meter and home weather station.

 

[HighDesertOffgrid]

"6 mph average wind speed" is the wrong kind of average.

For rainfall, (mean) average gives amount of water delivered.
Electricity delivers power proportional to square of voltage or current, so RMS.
Wind, power is proportional to cube of speed, so we need "Cubed ... Mean ... CubeRoot"

I don't understand your meaning. I don't know of any other statistical data from the NWS or NOAH pertaining to wind speed other than mph?

 

[sunshine_eggo]

For braking, I have an a/c electric water heater programed as a dump load for excess solar and wind. It gradually increases current to the water heater element starting @ 27.5V and ramping up to 100% of 2000 watts at 28V. This, along with standard ac loads, has been effective.
Right now it is producing 28 watts at at 27.5V at 3mph wind speed according to my clamp meter and home weather station.

Your data are bad. The maximum power that can be extracted from the kinetic energy of a 4' diameter column of air moving at 3mph is 1.725W. Yes, under 2W.

In order for your 4' diameter turbine to extract 28W of power, the wind needs to be 11.5mph assuming a typical 30% efficiency rating.

 

[HighDesertOffgrid]

Your data are bad.

The clamp meter and weather station have some inefficiencies, I'm sure. That is the data I gathered, along with my original post.
(on edit: the turbine is not turning and clamp meter still shows .98A. Not sure if it's the meter or the rectifier?)

 

[sunshine_eggo]

The clamp meter and weather station have some inefficiencies, I'm sure. That is the data I gathered, along with my original post.

Weather stations tend to sample several seconds apart (mine is like 18 seconds). I'm just saying that there's no way your turbine is collecting 28W in 3mph wind. That's below the start-up speed. I'm saying in order for your turbine to collect 28W, wind has to be moving at 11.5mph.

If your wind turbine is significantly higher than your weather station, you're going to get faster wind speed. If your anemometer is influence by turbulence from structures, it will typically read lower.

 

[HighDesertOffgrid]

Weather stations tend to sample several seconds apart (mine is like 18 seconds). I'm just saying that there's no way your turbine is collecting 28W in 3mph wind. That's below the start-up speed. I'm saying in order for your turbine to collect 28W, wind has to be moving at 11.5mph.

If your wind turbine is significantly higher than your weather station, you're going to get faster wind speed. If your anemometer is influence by turbulence from structures, it will typically read lower.

You are correct on all counts. I edited my last comment to reflect that. There is a very light breeze at the moment, enough to spin the prop, but not enough to get breaking voltage or an accurate reading on the ammeter. I could disconnect the leads and get a more accurate reading in millis but I'm not that motivated.

 

[OzSolar]

My toddlers reaction to the first time he saw/heard my turbine spinning up was priceless

"Ooo ooo ahhh!!"

That alone "makes a very small wind turbine worth it". Thanks for sharing!

 

[HighDesertOffgrid]

assuming a typical 30% efficiency rating.

Although... we should ascertain where this typical 30% rating comes from and if it applies to micro wind turbines designed for low winds. Most wind generation data is going to come from large commercial turbines with a much larger rotating mass than my toy.

 

[OzSolar]

I can personally testify as well as point to studies that painfully document that ALL small wind turbines will have a negative financial ROI when used in grid tied systems. That is, they will cost you more money to purchase, install and maintain than they will ever save you.

Oh sure someone one will point out a very unique situation with some pretty hefty incentives but those are the exceptions that hide the true economics. Please prove me wrong, all I ask is that you supply data. I want to be wrong because I really want small wind to work.

Off grid is a bit of a different beast though. No, I'm not saying small wind makes sense for off grid. It will be a complete loser compared to solar in regions that have sun 12 months per year. But it will likely be cheaper per KWH than a gas generator when you don't have any sun.

 

[HighDesertOffgrid]

I can personally testify as well as point to studies that painfully document that ALL small wind turbines will have a negative financial ROI when used in grid tied systems. That is, they will cost you more money to purchase, install and maintain than they will ever save you.

Oh sure someone one will point out a very unique situation with some pretty hefty incentives but those are the exceptions that hide the true economics. Please prove me wrong, all I ask is that you supply data. I want to be wrong because I really want small wind to work.

Off grid is different beast though. No, I'm not saying small wind makes sense for off grid. It will be a complete loser compared to solar in regions that have sun 12 months per year. But it will likely be cheaper per KWH than a gas generator when you don't have any sun.

I would go as far to say that any wind DOES NOT makes sense as an ALTERNATIVE to solar at the present (except in Fairbanks, AK maybe). It has no place in any grid tied system for financial ROI. As a supplement to solar in off grid applications it may have a place because it is hard to put a monetary value on the ability to make coffee with your batteries before sunrise.

 

[sunshine_eggo]

Although... we should ascertain where this typical 30% rating comes from and if it applies to micro wind turbines designed for low winds. Most wind generation data is going to come from large commercial turbines with a much larger rotating mass than my toy.

Micro wind turbines are by definition not designed for low winds UNLESS they have a high blade count. The high blade count usually means a lower cut-in speed, but the additional blades actually reduce overall efficiency.

I realize I'm coming across as mostly negative. That's not my intent. I'm very glad you have something that is giving benefit. Part of me still wants to go with a ~7' dia micro turbine, but even then, the ROI is very very poor, and we get some crazy winds up North. A full installation on a 24' tower is about $2400.

Problem is the average is pretty sad: 8-10mph. That means 80W when I'm lucky with many days pulling in nothing. There are a lot of MWandS installations in my area, and most of the time, they're not spinning. On average, it will produce the same as about 300W of solar.

Due to the gusting and turbulence, I'm also inclined to go VAWT, but that performance is even more atrocious.

 

[HighDesertOffgrid]

Micro wind turbines are by definition not designed for low winds UNLESS they have a high blade count.

My time in the pilot's seat infers that blade pitch has a role to play in that equation. The big boys (turbines) have variable pitch built into the design (which I may play with in the future for fun). But blade count isn't the only factor.

I realize I'm coming across as mostly negative. That's not my intent

I have no internalized need to be right. I enjoy the discussion.
I may look into a Hurricane Wind 1000w. They don't have certs, but seem to have good reviews.
Carry on eggo!

 

[Hedges]

I don't understand your meaning. I don't know of any other statistical data from the NWS or NOAH pertaining to wind speed other than mph?

Miles per hours is good, but my point is that linear "mean" average isn't weighted in a way that relates to power production.
The average would need to be of speed raised to the power of 3, because power production is proportional to that.


1 mile per hour average and constant 1 mph 24 hours day won't produce anything from a turbine, and energy theoretically available is proportional to 24 x 1^3 = 24 <something> units. and 1 mph average.

0 miles per hour 23 hours followed by 24 miles per hour would make power, energy proportional to 1 x 24^3 = 13,824 <something> units. but 1 mph average.

The latter is 576 times greater.
I think it is same has having a constant speed of (24^3/24)^(1/3) = 8.3 mph (not "average" of 1 mph)

 

[pollenface]

ROI $ is not as clear cut as a simple wattage calculation for me. As the majority of my winds are after sundown, lessening cycle depth plays some part on battery life. I don't have any with/without wind assistance longevity data, but I know it helps some.
As heat is the enemy of electronics, taking some load from my charge controllers during the day helps to a smaller degree as well.

Model:
View attachment 117689

For braking, I have an a/c electric water heater programed as a dump load for excess solar and wind. It gradually increases current to the water heater element starting @ 27.5V and ramping up to 100% of 2000 watts at 28V. This, along with standard ac loads, has been effective.
Right now it is producing 28 watts at at 27.5V at 3mph wind speed according to my clamp meter and home weather station.

This is the exact unit I have. The most I've seen it produce is 221w. The included charge controller brakes it at 14.3v or 28.7v (it's always outgunned by the SCCs). It needs a much bigger tail to stay in the wind, otherwise the blades act as a vain as well in turbulant wind and casuing it to spend more time rotating back and forth instead of spinning.

I can't really comment on it's annual production because I can't say I had it mounted in an optimal position not to receive turbulent wind. I have recently moved house though and have a 4m high shed on the highest point of land for as far as I can see, when I was on the shed roof putting up the solar panels I noticed a strong constant wind current, I think the turbine will do well on the new shed, I just haven't put it up yet.

I would like to try a 5 blade model as well at some point

 

[HighDesertOffgrid]

Miles per hours is good, but my point is that linear "mean" average isn't weighted in a way that relates to power production.
The average would need to be of speed raised to the power of 3, because power production is proportional to that.


1 mile per hour average and constant 1 mph 24 hours day won't produce anything from a turbine, and energy theoretically available is proportional to 24 x 1^3 = 24 <something> units. and 1 mph average.

0 miles per hour 23 hours followed by 24 miles per hour would make power, energy proportional to 1 x 24^3 = 13,824 <something> units. but 1 mph average.

The latter is 576 times greater.
I think it is same has having a constant speed of (24^3/24)^(1/3) = 8.3 mph (not "average" of 1 mph)

Okay, I'm tracking you now. One would think that kind of information would be compiled from the official wind stations and a true power generation average for a given site would be available. Does that kind of database exist?

 

[HighDesertOffgrid]

It needs a much bigger tail to stay in the wind

This was my first one. It was a 5 blade turbine (supposedly) rated for 1200 watts. After weeks of wind tunnel testing, my engineering team devised this tail extension. It helped so much that the 16 ga. wiring in the slipring had a meltdown during a windstorm.

 

[OzSolar]

I would go as far to say that any wind DOES NOT makes sense as an ALTERNATIVE to solar at the present (except in Fairbanks, AK maybe). It has no place in any grid tied system for financial ROI. As a supplement to solar in off grid applications it may have a place because it is hard to put a monetary value on the ability to make coffee with your batteries before sunrise.

Yeah that's what I said. Lol

There really needs to be a flow chart for small wind.

Step 1 - Do you want to save money or want to watch something spinning?

I think it's pretty clear where the flow chart goes from there.

 

[brandnewb]

I would go as far to say that any wind DOES NOT makes sense as an ALTERNATIVE to solar at the present (except in Fairbanks, AK maybe). It has no place in any grid tied system for financial ROI. As a supplement to solar in off grid applications it may have a place because it is hard to put a monetary value on the ability to make coffee with your batteries before sunrise.

In my scenario I have no more space for solar. My roof is already packed with them.
I am prepping for doomsday so I am not really concerned with ROI. I realize not everyone can do that at the moment so that is why I hope that once I have something spinning and producing then it could be copy paste for all of us here and for us to bypass all the trail and error costs. However little it produces.

Is that something you could get behind or even in such a scenario you are still leaning towards better not to go wind?

 

[HighDesertOffgrid]

Is that something you could get behind or even in such a scenario you are still leaning towards better not to go wind?

Sure. I would get behind that, once there was a working prototype that produced substantial power. Until then, I would probably build one of these.