SOLAR TRACKING SYSTEMS

Looks like a chain drive, smells like a chain drive, must be a chain drive: What you probably want is a "screw drive": Assuming identical gearbox efficiencies, each mechanism will require the same amount of power to lift a garage door or move a solar tracker.

Looking at the data sheets, they are available in 0.5HP (horsepower) and 0.75HP. 1HP = 746 watts. Assuming 75% efficiency, that's 500 watts and 1300 watts for 0.5 and 0.75HP respectively. Unless you insist on mounting your solar panels on your garage door, methinks the estimated power drain might be a bit on the absurdly high side.

Proabably too big and too much current: This particular EPAS (electronic power assisted steering) motor is rated 12v @ 65A. See the table on Pg 7.

On Fri, 23 Oct 2015 19:57:51 -0700, Jeff Liebermann Gave us:

No, it doesn't.

The only part have gotten correctly.

Off the mark a bit again.

A chain drive usually involves the chain being in motion. This has a fixed chain and the motor creeps along it by way of a rotating sprocket.

It is a variation of a chain drive, but not exactly what is defined by the definition of what a chain drive is.

Oh and it is actually more efficient than a worm drive as they have the screw thread friction to overcome, and must turn the entire screw length.

This crawler drive (just like that on a roller coaster incline, no chain in motion at all) does not suffer that loss.

On Fri, 23 Oct 2015 19:57:51 -0700, Jeff Liebermann Gave us:

Nope. Screw has thread face losses. Sprocket impinges against the chain link rollers and sees very little friction or loss.

you mean the motor moves along the chain? I haven't seen any like that.

I've seen plenty where the motor is bolted to the structure above the ceiling and pulls on a chain and the chain moves a slider and the slider is linked to the top edge of the door.

On a sunny day (Fri, 23 Oct 2015 16:07:27 -0400) it happened Phil Hobbs wrote in :

Absolutely true. Millions of LDRs are in the motion detection lights, preventing those from working doing daytime, I had one.

As to quantitative? I do remember in the old tube based TV studio LDRs were used in the sound mixer, a light bulb (Edison type) and an LDR in a tube, by changing the voltage on the bulb the audio level was changed,. No cracking faders? Master fader simple! OTOH it was the hobby or duty? of my boss at that time to look after the tracking.. replace bulbs .. The memory effect you mention never showed up in that application (sound guys would have killed him).

Start commercial

End commercial

Movie continued Maybe it only happens at lower light levels, I have noticed some very slow behavior at low light.

Once made a little car with LDR that would drive towards a light source. relays, maybe 1 transistor for each LDR, do not remember. An interesting adventure in robotics that I learned a lot from. Especially when it started going towards a light wall, then reversed getting into its own shadow, then forward again, oscillation! To me it showed the predicament humanity is in thriving for the higher goals, getting into its own ways. But that is for an other newsgroup. Maybe if you move towards a black or dark leader the effect disappears, but then will you move at all?

On 24 Oct 2015 07:08:15 GMT, Jasen Betts Gave us:

Maybe you thought the chain moves. Look closer.

On mine (and I have the top brand to my knowledge), the control unit is the large "head" module at the rear of the rail. Inside the rail is a length of chain, tied fast at the head end, and the other end of the chain is tied fast to the other end of the rail near the top of the door. Inside the small crawler module with the arm connected to the door, there is a motor, reduction gear, and a sprocket, and that is what gets fed the juice and runs its small motor and crawls along the fixed chain with teflon "slide bearings" along the rail. There is no motor in the large bulbous module at the rear of the rail, and the chain is motionless.

When you pull the release cord, it releases the reduction gear, and the door can be lifted and the sprocket "free wheels" along the chain until you pull the cord again and it returns the gearing engagement, locking the crawler head back onto the chain.

I hope I explained that so you will understand.

Essentially, the motor is right there at the arm you described, not back in "the head".

Do currently-available solar panels have any useful amount of output if you point them at a full, or nearly full, moon, or does that get into "it takes more power to run the tracker than you get back from the panel"?

Also, I realize that Jeff may be unable to personally test this idea, for medical reasons.

Matt Roberds

On Sat, 24 Oct 2015 09:35:00 +0000 (UTC), snipped-for-privacy@att.net Gave us:

Use one of these to power it... :-)

Here is why wind and solar will not be enough:

No: Full Moon = 0.27 - 1.0 lux Direct Sunlight = 32000 - 100000 lux

I have some thin film and amorphous Si panels that work somewhat better in low light than monocrystaline or polycrystalline panels, but they're not likely to be able to compensate for what looks like 5 orders of magnitude difference in luminous flux.

Yeah, that's a problem. Every time the full moon appears, I turn into a werewolf. I've gotten used to it, but it's still rather irritating having to clean all the fur and hair out of the bed the next morning. Medical solutions are unavailable mostly because Medicare and the insurance companies don't cover the problem. Next full moon is Oct 27 and you're right, I won't be testing panels by moonlight.

hello I have made a tracker, with analog aproach. I have measured on a 10w panel mountet at the tracker and a 10 w stationary panel this summer. I have a tr ee that take the sun from 2 to 4 in the afternoon.the panels was connected to the same battery, but I swithed them to the battery once at a time as I measured the current. I found ,by asuming the same current for an hour, unt il next measurement, that the tracker gave somwhere between 30 and 35 % mor e power than the stationary panel. I will see how it look in the autumn and winter too. The motors will draw a bit current ,as there always is a difference in the system. and I have made a pulsgenenerator, that deliver a one second puls t o the motors eacn 10th minut. first a pulse to horisontal then to the verti cal section ,then it take very little current. I had a similar system ,long ago, and I had to make a sun up detector with another BPW34 aimed at east. when the sun was up the sensor put current to the vertical section in oppo site direction and it mowed against east, and the sensor was then shaded by the tracker.. this arrangement worked well too. To get the turning speed very low, I have used gearmotors . its not perfect at all, but I'm sure it can be made to work well ,if time was invested in it. alex

Do an image search for windmill fire or wind turbine disaster

and such. Lots of fun pics. It will be interesting to see how those machines do in the long term. The offshore ones seem especially nasty to me.

No one asked you to use hydraulics. I was creating an analogy. Just never mind.

No one is talking about elevation. That is a relatively minor error in pointing. The point is that if a clock controlled, fixed mechanical drive is used, it would be at the wrong azimuth at all time other than one point during the day for any day other than the one day it is calibrated for. Sunrise and sunset vary widely over the course of the year. This will give significant error to the aiming during other parts of the day. Part of the reason why a sundial doesn't work well.

This one is only 30A. You only need to run it for seconds per hour. So, total daily power draws could be just a few watts. A small motorcycle battery can easily buffer and handle the power pulses.

I've looked close enough. if it doesn't move it's teleporting!

most recent was a predator brand unit installed 12 years ago. and previous to that some other units with fixed codes. they all used moving chains. and rails that came in pieces ans cosketed together like tent poles. this may have been so that they could be packed in into a box that looks good on a shelf at the hardware mwgastore.

I've not seen one like that before. what's the rail made from?

it seems a rack and pinion would be slightly more mechanically efficient than using a chain and sprocket, AIUI correctly cut gears are essentially frictionless.

On 24 Oct 2015 19:26:15 GMT, Jasen Betts Gave us:

Apparently not. Both ends are fixed and attached. It is a taut chain.

For the chain to move, there would have to be a sprocket at the door end and a drive sprocket at the head end, and TWO chains running in the rail. That makes the cain requisite twice as long, minimum.

News flash: There isn't. There is a SINGLE length of chain, and it is FIXED and TIED (held fast) on BOTH ends.

Do some math. The chain is STATIONARY.

The unit which attaches to the arm which attaches to the door has the motor and reduction gearing and sprocket on it and THAT element moves ALONG the length of the chain. This is the "tractor" or "trolley" assembly.

So again, the chain is NOT moving. The sprocket in the trolley moves ALONG the fixed chain.

Think of a "rack and pinion". The "rack" is the track with the chain length laying in it. The "pinion" is the sprocket in the moving, motorized gearbox of the door actuator assembly "Trolley". There is no motor in the main controller "head" end at all.

Far cheaper than milling gear teeth on a bar and putting that in the rail, and operating a pinion.

Read up on how the direct drive units work:

Part way down the page.

This is the perfect system for the task of this thread's topic. The only change would be selective on/off control instead of end-to-end running.

Consider yourself as having been 'taut'.

Now loosen up and learn something, boy. :-)

What does 'long term' mean? Holland has seen four centuries of windmills in operation, that should be long enough for any engineering design purposes.

For a really interesting failure, there's a video of a suspension bridge...