Are the sub $300, 400w wind generator from china/ebay worth it?

[Bicycle Bob]

Over at Airborne Wind Power, (kites) Dave Selsam is always telling horror stories about generators wrecked by high wind, but he's in Mohave. In general, cost per watt hour goes down as size goes up. If you are off-grid, and seriously simple in style, a small, high-quality could be enough, but you have to get it above the tree tops for good results, and the vibration is too much for a rooftop you live under. Then, you still need batteries, etc. If you can arrange for a water tower or some other 2-level water ponds, I'd be inclined to use wind to pump water up, and get electricity on demand from a hydro powered generator.

[Robaroni]

Originally Posted by davidbr13

Totally agree with Mikesolar. I have Hugh's 200 edition brakedrum windmill book. Its perfect for DIY. And he has an updated version available online that uses a different, even easier to build, generator design.

David,
There are better designs out now than the brake drum wind mill. Hugh has newer books with more efficient, longer lasting designs.

Rob

[Daox]

Does anyone have any links to online designs? I know there is Otherpower | Make Your Electricity From Scratch! that has some good stuff.

[Robaroni]

I have been monitoring the wind on my front field for several years now and I definitely have enough wind to get a benefit, especially in the winter when the sun isn't out very long and the trees are bare.

Remember, wind compliments the sun as someone else said here. They work together. Germany has been installing wind on its north shore to work with their PV.

You can get respectable power at lower elevations BUT you have to account for it. Instead of taking out a life insurance policy and kissing the family good bye every time you have to climb a hundred foot tower why not put two wind mills up on shorter poles? That's what I'm doing, so I get a little less power, I can live with it.

Wind is not like PV. you can't just put it in and walk away, it needs care and that means lowering the tower at least once a year. I plan on putting my towers up 40 feet, that's all. I have a monitor up about 18 feet and get good wind. Yes, there's more shear but if you have it in an open field shear is reduced.

The Chinese mills are modeled after the South West Air's. I bought two Air's several years ago but never installed them. The thing about wind is that you can only get so much out of swept area, you eventually hit the Betz Limit and can only extract so much from the wind relative to span.

The thing you have to watch is the wind speed some of these small mills get there "400" watt figure from. Most times it's around 10 or 12 m/s or about 25 to 30 mph. How many times do you get 25 mph winds? My monitor only hits 25 to 30 several times a year AND I'm in a good wind area, a company came in a few years ago wanting to put mills in because the wind is that good.

I suggest you monitor your wind for several months to a year and go look at the excellent charts for wind in your area before you invest in a windmill. If you go to South West's site they have wind maps and you can actually see your property.

Rob

[Robaroni]

Originally Posted by Daox

Does anyone have any links to online designs? I know there is Otherpower | Make Your Electricity From Scratch! that has some good stuff.

Daox,

Several years ago a friend of mine did some wonderful work with VAWTs (vertical access wind turbines). They have gotten a bad shake from guys like Hugh Piggot but they have some good points, especially for DIYers.

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Ed Lenz is a very knowledgeable guy, we were on Otherpower for awhile but, as nice, and knowledgeable as those guys are, the are in the business of selling magnets. Their design happens to use twice as many magnets as conventional designs.

I use conventional designs (hopefully I'll get one up here at some point) and what I do is go to motor repair shops and ask them to save me large fields of burnt out motors that i strip and convert to wind and water mills.

The other mistake people make is attempting to build a windmill with too large a span right off the bat. I suggest building a couple of small mills on short poles to learn about them first. The logistics and stresses of a 15 or 20 foot span mill is huge! Try starting with a 6 to 7 foot mill first or even Ed's design of a VAWT. Have some fun with it first, you'll build a much better mill your second or third time out.

Rob

[Servicetech]

We're in an decent wind area, Oklahoma of all places. Yeah, some of the highest winds on record have been recorded in Oklahoma. Yellow on the map linked above, not as strong as out in Western Oklahoma where all the windmill farms are though. Wind speed at time of posting 20mph/26gust which isn't out of the ordinary.

Not sure I'm ready to bite on a Windmill though even if considering are on top of a hill (TV towers less than 1/4 mile from us). Solar is a no-go due to the frequent hail storms in our area. Something to keep in mind, areas with consistent high winds are also subject to severe weather.

[Robaroni]

Originally Posted by Servicetech

We're in an decent wind area, Oklahoma of all places. Yeah, some of the highest winds on record have been recorded in Oklahoma. Yellow on the map linked above, not as strong as out in Western Oklahoma where all the windmill farms are though. Wind speed at time of posting 20mph/26gust which isn't out of the ordinary.

Not sure I'm ready to bite on a Windmill though even if considering are on top of a hill (TV towers less than 1/4 mile from us). Solar is a no-go due to the frequent hail storms in our area. Something to keep in mind, areas with consistent high winds are also subject to severe weather.

I've seen some pretty big stuff hit modules. I wouldn't be especially worried about hail especially if you tilt the modules when the weather predicts it. Modules are made tough, I've seen mine rock in 40 mph winds with no bad results or even a couple of feet of snow and ice on them. If you're worried about high winds mount the modules in a single row lower to the ground in short runs and fix the angle optimally for your area. Another trick I use is to leave a small gap between each module (3 or 4") to reduce the surface area the wind hits.
If you're getting 10 m/s wind speeds consistently then you should seriously consider the windmill option.

rob

[Servicetech]

Originally Posted by Robaroni

I've seen some pretty big stuff hit modules. I wouldn't be especially worried about hail especially if you tilt the modules when the weather predicts it. Modules are made tough, I've seen mine rock in 40 mph winds with no bad results or even a couple of feet of snow and ice on them. If you're worried about high winds mount the modules in a single row lower to the ground in short runs and fix the angle optimally for your area. Another trick I use is to leave a small gap between each module (3 or 4") to reduce the surface area the wind hits.
If you're getting 10 m/s wind speeds consistently then you should seriously consider the windmill option.

rob

Here's what the hail storm of 2010 did in our neighbourhood, there were several holes in my roof the size of that in the 1st photo. That would be one tough solar panel not to have broken in that storm !!

[MN Renovator]

Whoa! Straight through the decking!! That's insane! Is that OSB?
Architectural shingles won't save you there.

Here's the question, your homeowners insurance would cover the roof but what sort of coverage do you need to protect a solar system?

[Servicetech]

Originally Posted by MN Renovator

Whoa! Straight through the decking!! That's insane! Is that OSB?
Architectural shingles won't save you there.

Here's the question, your homeowners insurance would cover the roof but what sort of coverage do you need to protect a solar system?

Yes, holes through OSB decking in several spots. It would have KILLED anybody that was out in the storm unprotected, but we didn't have any injuries from it. You saw where it fractured the wind shield in the neighbours car? Architectural shingles went back on the roof, may help with a minor hail damage. Not sure about insurance for the panels, be we got a nice little hike after the storm went through. We're at about $1,300/yr already !!