september

[Capt Slog]

I realised that I might not able to get enough power from the infrequent wind here and just the one PV panel. I plan to use an inverter that will be 'always on' to power some house lights, and this will use it's share of power to run. So I went and bought another 80w.  This arrived within a few days and I excited unwrapped and tested it.  

I'm afraid it was a bit of a disappointment.  It was slightly bigger thanthe previous panel and there were 40 cells on arranged 10 x 4 rather than the 9 x 4 that i had already.  That wasn't the trouble though.  The problem was that it didn't give anything like the same output for the same light conditions; where the old panel was kicking out 17volts, this new one wasn't managing 12 !  Not good at all.  I also noticed that the two 'sides' of the panel were not matched.

I phoned the shop and they agreed after a bit of haggling to have it back.  rather than beingsent a duffone again, I decided to go to the place personally and took a meter with me.  I had several panels out in the sunshine and in the shade and took home the one that I liked the best along with £10 for my petrol.

The panel is now mounted on the foof and kicking out lots of charge.

Next, I decided to do something with my blades on the wind turbine.  If you're already bored with reading this saga, go no further, otherwise....

A few months ago I made some wooden blades instead of the PVC pipe things I had been using.  I put them on but was never completely happy, they just didn't seem to spin like I thought they would.  One day while i was watching and testing the output I noticed that they weren't doing the job.  I confirmed this by quickly swapping back to the plastic set and watched the power DOUBLE; definitely not right.

The wooden set languishedin the shed untill this month when I took them out and had a really good look at them.  What i noticed was that the front (wind) side of the blade wasn't as flat as it should have been, it was actually convexed.  So I set about cutting more wood off all three blades, eventually getting to a profile that was very slightly concave on this front edge.  In taking the wood off, I also sharpen the trailing edge, by the time I'd finished it would take a kangeroo's head off if it was a boomerang.

I then made some balancers, I've noticed in the past how much power is mopped uip by even a slight wobble.  I'd just made them when I saw a post that refered to them as Jubbly's, perhaps I'd seen them a long while before and they stuck in my mind.  Anyway, I made three, and mounted them opposite each blade behind the front plate in the recess between the blade roots...

They are made from 1" brass bar tapped with 2BA thread so that they can be adjusted on the 2BA bolts, and locked with nuts.  The bolts go through bits of aluminium angle and I was able to achieve very fine balance once I'd mounted the blades on the turbine.

I finished off by making a nice front boss to cover all the screws and keep the water out, this was all sealed with silicone as were any wood to metal gaps.

The new blades seem to perform much better, certainly adequate for the moment.  The main problem will always be the turbulent winds I have here.

[Flux]

If the alternator suits pvc blades then it is probably very slow and you are stalling with the wooden ones.

Flattening the front face will effectively alter the pitch and may bring you nearer the curved single surface of the pvc. Normally having the front face flat doesn't matter much but it requires the blades set at a different angle and raises the tsr.

To even approximate the pvc things you may have to under cut the front face and make it concave to get a higher lift.

These high lift type blades do seem to work better in low and turbulent winds, but for every blade type the matching to the load makes more difference than the actual blade form.

If you have an extra 6v battery just give your mill a try into 18v and see what happens. If it takes off and works far better then try at 24v. When you know where you are you can alter things to suit.

Flux

[Capt Slog]

Thanks Flux.  You've tried to help me before with this and recommended the 24v tryout then.  I didn't have a go because after watching very carefully I didn't feel the problem was stall in that sense; most of the time the mill is sitting at well under the battery (12v).

When there is wind I do get charge, but it's difficult to take measurements.  I can't say what I get in watts per wind speed which I think could be helpful.  I've seen you say before that wind is very deceptive, it seems to be blowing trees but there really isn't much there.  I'm going to have to employ the services of a son to help me, perhaps one of us looking at the wind gauge while the other looks at the voltage, I can then get some serious data

I've already accepted that I don't have enough constant wind to make it truly workable, but it's worth it for the times when I do.  I see it as thoroughly testing out the design for a time when I could be able to put it much higher or on the house (!)

.

[margusten]

Hi,

Good idea to try 12V, 18V, 24V, 30V, 36V battery set to find out max power Your blades and alternator mach.

Higher tower can help always to increase harvested power.

But usually tower height is limited.

Alternator should match blades. Here is my experiment:

Initially built 2m diametre fixed pitch plywood blades. Not spinning at all. Never reaching charging voltage.

Then added some pvc blades to top. Now over 3m diametre. Spinning easily but too slow.

Then added more pvc blades to centre. Suddenly this thing start working.

At high winds I can hear some strange noise like big trees do, bending in high wind.

Let's see how long this creature can hold in one peace.

This windmill has one problem more.

Some old automobile bearings are too tight, not spinning freely. Only 3m diametre blades can make it spin. I suggest to use bearings You can take a part.

Margus