Author Topic: I'm TRACKING!  (Read 15333 times)

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Elby

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I'm TRACKING!
« on: May 29, 2011, 04:53:24 PM »
Wonderful, wonderful feeling when it first took off, heart stopping moment when it quit, till I remembered that it would cycle on/off till it achieved equilibrium.









Next step is to build a self charging capacity into it. A Lawnmower type battery will just fit inside the Box mounted to the pole.

I have a Harbor Freight 5-watt (I think) solar panel. Any guesses if that would be sufficient to maintain the tracker's battery? Also could something as simple as a LM317 voltage regulator be used to prevent over-charging? I don't think the HF unit has any type of protection for the battery.

chainsaw

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Re: I'm TRACKING!
« Reply #1 on: May 29, 2011, 05:07:41 PM »
I use a lawnmower battery that is charged by a 10 watt panel.

Runs three (Redrok) trackers with no problem.

I really like the cover for your sensor, what and where did you obtain it?

Harold in CR

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Re: I'm TRACKING!
« Reply #2 on: May 29, 2011, 05:14:46 PM »

 Home made or bought ?? How much ??  Nice install. I'm hoping to FINALLY get my panels built, toward the end of this month.  ::) ::)

Elby

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Re: I'm TRACKING!
« Reply #3 on: May 29, 2011, 05:18:10 PM »
It's an outdoor light fixture from lowes. Not my idea, I copied somebody else. Find the "Outdoor Lighting" section. They'll have everything mounted on the wall, exit signs and such, then look up at the bottom of the top most shelf and you will see this light, it has an aluminum cage on it that's supposed to protect the glass. I never could find it on their on-line store.

I found got the idea from this guy's site:
http://www.briery.com/solar/parts_list.html

birdhouse

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Re: I'm TRACKING!
« Reply #4 on: May 29, 2011, 05:53:35 PM »
elby-
nice work!  i think those light fixtures are the type used in explosion potential areas.  areas with high fumes ect, where a broken light bulb (spark, flame) could send the whole joint up!

i like your box in a box in a box for the sensitive electronics.  that should keep the water out! 

how many watts are you planning on putting on that rig?

kudos!
adam

Elby

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Re: I'm TRACKING!
« Reply #5 on: May 29, 2011, 06:32:11 PM »
Plan?!

Seriously don't know. The project started out as a solar concentrator, but the wind caught my dish while it was propped up against the shop and bent it pretty good. So bad that I just got rid of it. I'm kinda poor right now, but I got to thinking about it the other day and realized I had almost all the parts for it already. In fact the entire mount with linear actuators has been mounted in the back yard for 2-3 years now, it just needed put together.

They're very similar to explosion proof lights (what I originally wanted), but much cheaper made. Nowhere near code compliant for explosion proofing.

I just (almost) had a bad bad thing happen. When I went out to marvel in the glory of backyard technology, I noticed that the actuator for altitude was within 1/8" of the control box and still climbing. I got it stopped,  I dropped the box 4-5 inches and it can now travel lock to lock without interference. Thing is, I was certain it would clear from when I put it together. Oh well, good opportunity to go back and check how far it travels while checking for interference. BTW, E-W is +/- 60 degrees from center, N-S is 30 to 88.5 degrees from horizon.

Seriously everybody, thanks for the positive comments!

ghurd

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Re: I'm TRACKING!
« Reply #6 on: May 29, 2011, 10:12:06 PM »
"Also could something as simple as a LM317 voltage regulator be used to prevent over-charging?"
Not really.
(it can work on paper, but real life can have issues with 5W of solar)

Try PB137ACV, and heat sink it far too much more than it looks like it requires.

I 'almost' doubt a FLA lawn mower battery needs any regulation with a 5W HF PV.

Looks great!
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jaysicle

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Re: I'm TRACKING!
« Reply #7 on: May 29, 2011, 10:30:41 PM »
Brilliant Elby !. I would love to set something like that up... Nice work.
Marble cake is hard on the teeth.

hydrosun

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Re: I'm TRACKING!
« Reply #8 on: May 31, 2011, 08:36:13 PM »
My tracker circuit lives in an old peanut butter jar. I've got the glass water proof light cover like yours down by my hydro turbine with a 24 volt bulb.
Chris

Elby

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Re: I'm TRACKING!
« Reply #9 on: June 12, 2011, 11:26:04 PM »
Dunno if it matters to anyone, but in the last two weeks I have had a voltage gain on the battery from 12.2 volts to 12.5 volts.

Battery is a Interstate "Workaholic" 660cca /825ca. Energy usage is a Redrok 2-axis tracker, and two linear actuators being driven lock-to-lock through the day and return after dark. PV panel is Harbor Freight 5w mounted on tracker. Weather has been mostly clear, sunny and HOT! 100+ temps.

Looks like that the PB137ACV is going to be a must-have and the 5w panel will probably be sufficient for a drive power source. For temp, I've just unhooked the PV panel to keep it from getting out of hand.

Bruce S

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Re: I'm TRACKING!
« Reply #10 on: June 15, 2011, 01:10:16 PM »
Dunno if it matters to anyone, but in the last two weeks I have had a voltage gain on the battery from 12.2 volts to 12.5 volts.

Looks like that the PB137ACV is going to be a must-have and the 5w panel will probably be sufficient for a drive power source. For temp, I've just unhooked the PV panel to keep it from getting out of hand.
That's good news! It is always good to see updates on things that workout  :)
Here's hoping that battery gets up to 13.5Vdc where it really should be for long life  ;D
Not sure what you mean by unhooked though, did you disconnect the panel due to the outside temps? if so they'll probably be okay, mine did ad they're the HF15watters.
The little 5watter I have did as well even while still in its RED surround.

Cheers!
Bruce S
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Elby

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Re: I'm TRACKING!
« Reply #11 on: June 15, 2011, 06:23:23 PM »
Sorry, I shouldn't have abbreviated "temporary" immediately after discussing the temperature. Bad form on my part.

Because I've got about a thousand irons in the fire right now, I just unhooked the leads going from the PV to the battery on a temporary basis. That way I can't forget about it. The regulator and a few sundries should be here soon thanks to a very kind board member and then I'll make a permanent connection to the lawnmower battery that I've gotten for it. After that, I gotta start thinking about making actual use of it. It looks kinda goofy having a tracker that size with only a 5w panel mounted on it.

Voltage was measured at night, without the panel charging. I know a battery actively being charged should be higher than 12 volts (up to 14.5), but I thought 12.2 to 12.5 indicated a fully charged battery when not being actively charged. I could easily be very very wrong about that.

Elby

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Re: I'm TRACKING!
« Reply #12 on: June 15, 2011, 06:45:18 PM »
It looks kinda goofy having a tracker that size with only a 5w panel mounted on it.

See.



One thing I've noticed that I didn't plan for, is that the sun's angle seems to be coming from just a touch north of due west in the latter part of the day. As a result I can't directly aim at the late day sun. In retrospect that seems obvious due to seasonal changes in the earth's orientation to the sun. I've looked at some of the online solar calculators, but it looks like they all give angle at a specific date/time, not the maximum / minimum a location will receive. Is there a better way to go about calculating this effect? Without manually inputting every possible combination that seems likely?

I'm probably not making much sense the way I'm asking this. I can get the max, and min, sun's angle relative to the horizon, what I would like to know is the maximum amount that the sun's position would appear to be north of due west.

ghurd

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Re: I'm TRACKING!
« Reply #13 on: June 15, 2011, 08:07:19 PM »
That sure is funny-looking.

Lat + 24 degrees?  Just the knee jerk response.

I did not put a lot of faith in tracking before.
Now, after many years of watching the sky, I do.

Today is a good example.  Bright clear blue sky. Until about an hour or 3 after sun rise.  Cloudy all day.  Now, with 2 hours until sun set, bright blue sky.
Today would make most PV power whem the power should be dropping off.
The vast majority of todays solar power, here, would have come from South of an East/West line.

I need to test a thing or 2, so I have been watching.  Even if I can't do it when it it is a good time.   :(

I am in the snow belt.  Here, winter is much worse.  It happens very often, sometimes for weeks on end.  Can go many days without a shadow, but the night stars are bright.  I have much less faith in the carts and calculations than a did a few years ago (for here), and I believe tracking could make some major improvements over the calculated solar insolation for PVs.
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Bruce S

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Re: I'm TRACKING!
« Reply #14 on: June 16, 2011, 09:11:05 AM »
Sorry, I shouldn't have abbreviated "temporary" immediately after discussing the temperature. Bad form on my part.

Because I've got about a thousand irons in the fire right now, I just unhooked the leads going from the PV to the battery on a temporary basis. That way I can't forget about it. The regulator and a few sundries should be here soon thanks to a very kind board member and then I'll make a permanent connection to the lawnmower battery that I've gotten for it. After that, I gotta start thinking about making actual use of it. It looks kinda goofy having a tracker that size with only a 5w panel mounted on it.

Voltage was measured at night, without the panel charging. I know a battery actively being charged should be higher than 12 volts (up to 14.5), but I thought 12.2 to 12.5 indicated a fully charged battery when not being actively charged. I could easily be very very wrong about that.
No problem on the temp thing  :P
Fires in the iron ? OOO-boy do I understand that part!!
The true test of a batteries health is of course the SG(specific Gravity) however for tesing purposes and the like a lawnmover type Lead Acid battery should normally be reading up much higher more like 13.5 or better depending on the type. There should be a label on the battery (newer ones) stating it's normal voltage range even more if it's a name brand. IF however you're like most of us  ;D and grabbed a battery you already had, then try getting the battery up to 13Vdc.
I think the tracking system is Umm HAS character  ;) yeah that's it  ;)

Putting it to good use, here's what I started with after the euphoria drop off to manageable levels.
I went around the house grabbing ALL the cell phone and battery chargers. For 12V I added cig lighter adapters (started with 4 on a switch found in clearance isle at Wally world for $1.50, and for battery chargers got an old 300 watt inverter.
With these I stopped having walworts for cell phones and battery chargers. IF I accidentally left everything on and drained my system, then I had to due "work" by hand.
Boy that'll quickly teach a person Solar power management in a quick way.
Hope that helps!!
MOST OF ALL HAVE FUN WITH IT  ;D
Cheers
Bruce S
 
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conntaxman

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Re: I'm TRACKING!
« Reply #15 on: August 17, 2011, 02:36:05 PM »
Elby. where did you get the tracker? did you find a cir, or make the cir. and could you Post the cir. OR did you buy the tracker.
you never did mention where you got the tracker.
Many would like to see the cir, if you can post it.
tks
John

Elby

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Re: I'm TRACKING!
« Reply #16 on: August 18, 2011, 10:32:29 AM »
It's a redrok tracker, http://www.redrok.com/

There's another post (previous to this one) that covered the specific tracker, problems I had with it, and how it was fixed.
http://fieldlines.com/board/index.php/topic,145446.0.html

If you're looking to design your own, the best help I can be to you is to point out that this tracker is pretty thoroughly laid out on redrok.com, if you want to take the time to dig through all the info that's there.

defed

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Re: I'm TRACKING!
« Reply #17 on: August 24, 2011, 06:07:07 PM »
when tracking, how do you determine the angle you will need to rotate to the east and west?  do you go basically as far as you can?  or are there some factors used like when you determine your seasonal tilt?

i am looking to make a traxle type mount.  if i could figure out how much i need to rotate east/west, it would help in designing it as to keep it as compact as possible w/o having any moving parts crash into the legs when rotating.  for example, my main tilt is 45 degrees (+/- 15).  if i make the legs in a vertical "A" frame, the panels would hit the legs at maybe a 45 degree rotation to the east/west.  i can get around this if i have to, but if X degrees is far enough, then i can determine if it will clear w/o extra engineering.

the pictures i was looking at have the array at a 60 degree tilt, and then the rear legs are also at a 60 degree angle.  this allows the rack to rotate and miss the legs.  putting my legs at 45 degrees will make the overall footprint too large, and the pipe for those legs rather long. 



Elby

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Re: I'm TRACKING!
« Reply #18 on: August 24, 2011, 07:13:24 PM »
Mine was built for max angle tracking East to West. Go much further and the frame will severely bind on itself. This is more than sufficient due to the local landscape, which blocks the sun very early and very late in the day.

I "planned" to only go to just shy of straight up, and as far down as was convenient in the North to South mode. My reasoning was that unless you are at the Equator, the sun should always appear to be less than straight up (or just slightly South of straight up). This logic appears to be true only midday. In the afternoon the sun can appear a little north of a true East-West line. At which point my tracker hangs up on it's limit switch. I do not fully understand and will not try to explain why, just observe that it happens.

Moral of this story, measure twice, cut once.

defed

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Re: I'm TRACKING!
« Reply #19 on: August 24, 2011, 07:31:38 PM »
here is what i'm looking to build:

http://www.solar-trackers.com/cz/

not a very good picture, but good enough to get the idea.

the frame is tilted at a fixed angle, looks to be 60 degrees in the photo.  when it rotates on its axis, in theory, it could rotate until vertical.  as you say, this is probably not necessary as the sun is usually not visible all the way to the horizon.  but, in a perfect scenario, would you want to rotate from vertical facing east to vertical facing west?  you can see the actuator they use to rotate, and i'm sure that can't go vertical to vertical anyway...so my guess is you rotate as far as the equipment will allow you to.

rossw

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Re: I'm TRACKING!
« Reply #20 on: August 24, 2011, 08:26:38 PM »
not a very good picture, but good enough to get the idea.

the frame is tilted at a fixed angle, looks to be 60 degrees in the photo.  when it rotates on its axis, in theory, it could rotate until vertical.  as you say, this is probably not necessary as the sun is usually not visible all the way to the horizon.  but, in a perfect scenario, would you want to rotate from vertical facing east to vertical facing west?  you can see the actuator they use to rotate, and i'm sure that can't go vertical to vertical anyway...so my guess is you rotate as far as the equipment will allow you to.

Also not a very good photo, but here's one of mine. I built 4 of these, 600 watts each. The geometry is such that the linear actuator will tip the array from about 15 degrees off vertical east, through horizontal to about 15 degrees of vertical west. Ie, around 150 degrees total. The arm it's mounted on also tilts for seasonal control, which is much easier to achieve with this sort of construction than a traxle.

defed

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Re: I'm TRACKING!
« Reply #21 on: August 24, 2011, 08:51:32 PM »
i was debating between single pole mounts and other 'multi-pole' mounts.  the big negative for the single pole is that i wanted to try to get all 10 panels on one pole...this means a fair amount of concrete in one mass.  w/ a traxle, i could get the same amount of concrete in 3 or 4 holes meaning i could mix it myself in smaller batches.  i have some ideas to make seasonal tilt easily adjustable w/ the traxle.

what is the area of your 6 panels?  how much concrete did you use to support the pole?  i'm not entirely against a cpl small single pole mounts...even w/ a 10 panel traxle, i would need to add another if i add more panels in the future.

Volvo farmer

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Re: I'm TRACKING!
« Reply #22 on: August 24, 2011, 10:30:56 PM »
I have a couple of mounts like RossW's, also with about 600W of panels, (four 165's) and they has survived four years now. My pole is about 3.5" OD,  and round, not square.  One thing that is extremely nice about this type of pole mount is the ability to adjust north/south for seasons. It literally takes me three minutes with two crescent wrenches to adjust one of these types of mounts from winter to summer. Also, if the tracker quits, I still have a nice pole-mounted array, off the ground and out of the snow, and easy to adjust for the seasons.  My second mount only has about four bags of concrete in the hole. I think it's easier to go deep than to pour massive footers, and I've done it both ways.



As far as east/west... Yes, you try and get the maximum without physical interference or running out of actuator. In all practicality, I believe an extra 10 degrees towards vertical will get you very few extra watt/hours. There's a lot of atmosphere for the sun to pass through in the early morning/evening.

My mount had a 8' solid c-band satellite dish on it so I sized my square footage to approximate the dish size.  If you want to track ten panels of modern sizes (150+w) I think you're going to need two or three pole mounts, unless you want to engineer some monster rack. I saw a commercial freestanding pole mount  with ten 120 watt panels on it last week and I think the pole was about 8" in diameter. 
Less bark, more wag.

rossw

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Re: I'm TRACKING!
« Reply #23 on: August 25, 2011, 12:48:49 AM »
i was debating between single pole mounts and other 'multi-pole' mounts.  the big negative for the single pole is that i wanted to try to get all 10 panels on one pole...this means a fair amount of concrete in one mass.  w/ a traxle, i could get the same amount of concrete in 3 or 4 holes meaning i could mix it myself in smaller batches.  i have some ideas to make seasonal tilt easily adjustable w/ the traxle.

So did I. I even built a traxle. It was more trouble than it was worth and I've since pulled it apart.

Quote
what is the area of your 6 panels?  how much concrete did you use to support the pole?  i'm not entirely against a cpl small single pole mounts...even w/ a 10 panel traxle, i would need to add another if i add more panels in the future.

My modules are (from memory) 1.1 x 0.67m or 4.4 sq m for the whole 6. (about 47 sq ft)

I dug deepish holes, positioned the post, and filled with concrete. Not so much concrete but I think its much more effective than a big shallow chunk! I have 4 of these arrays, plus 2 more that don't track (seasonal only).

I think you'd probably be far better off putting them in a line, north/south, far enough apart that they won't shade each other in winter. 2 or 3 arrays like this are far more managable than one monster.

defed

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Re: I'm TRACKING!
« Reply #24 on: August 25, 2011, 05:38:40 AM »
i have a couple problems that limit me on a single pole mount.  first, i can't go deep.  i hit water at 4', so i need more surface area as opposed to depth.  second, i can go east/west easier than north/south when positioning arrays.  this has limitations, as you can get shadowing of each other.  in this case, it would be easier to get as many as possible in one location.  how would you determine the positioning?  i just had a thought of 3 single poles set in a triangle.  one out front and one each staggered to the north east and west.  the rear 2 would be on the same plane, but far enough apart as to not affect each other.

don't get me wrong, i would love a single pole....easier to mow around, etc...but w/ my limitations, a multi-pole setup would alleviate some engineering issues.

all 10 panels together would be approximately 10' x 13'.

i have pages upon pages bookmarked of various single pole and multi-pole mounts...check this thing out:

http://voodoosolar.com/pg_04.html 

Volvo farmer

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Re: I'm TRACKING!
« Reply #25 on: August 25, 2011, 08:46:57 AM »
i have a couple problems that limit me on a single pole mount.  first, i can't go deep.  i hit water at 4', so i need more surface area as opposed to depth. 

If you look at my back array, it has a big chunk of concrete poured on the surface. I hand-dug the hole to about 18" and poured in a couple bags of quickcrete, but it was wobbling in the wind. So I framed it up with 2x6's and poured a slab around the pole. 

 
Quote
second, i can go east/west easier than north/south when positioning arrays.  this has limitations, as you can get shadowing of each other.  in this case, it would be easier to get as many as possible in one location.  how would you determine the positioning?  i just had a thought of 3 single poles set in a triangle.  one out front and one each staggered to the north east and west.  the rear 2 would be on the same plane, but far enough apart as to not affect each other.

They make a tool called the Solar Pathfinder, but it's about three hundred bucks.  If it were me, I'd go drive a few tall stakes in the ground where you think you might like the arrays, then watch the sun over a few day period.  I agree with Ross, you want them in a north/south line if at all possible. You could make the pole shorter on the northernmost array so that you could place them closer together.

Quote
all 10 panels together would be approximately 10' x 13'.

My panels are 54 square feet, and I did not feel comfortable going to 81 SF or 6 panels/rack.  My 8' satellite dish was about 50 SF. It all depends on your mount, but you might get away with 5 panels/rack at 65 SF each.  The wind can be a harsh mistress on tracking racks. It's not unusual to have a pretty good gust come up late in the evening, when the tracker is nearest to vertical.
Less bark, more wag.

defed

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Re: I'm TRACKING!
« Reply #26 on: August 25, 2011, 04:08:29 PM »
trust me, i know about the wind....which is why i'm always paranoid about having a large enough chunk of concrete to hold it upright.  it gets pretty nasty here, which is why i've been working on a turbine.  in fact, i started w/ a turbine then added solar, now the turbine is on hold while i get the solar wired up.

anyway, i was making some sketches and maybe i can't seasonally adjust a traxle as easy as i thought i could...+/- 15 degrees is a fair amount.

so, now i might be leaning towards smaller single pole mounts.  6 per pole, about 80 sq ft.  this is approximately the same area as a 10' dish (which i have one up).  if i put them in 2 rows, 1 in front north and 2 behind staggered east and west, the 2 in the back would be quite far apart i think.  i mean, they will each be 10' wide, so the 2 back ones would be at least 15' apart by the time i leave some room for them to clear the north array.  what is the rule of thumb for north to south spacing?

i've seen my 10' dish get beat up in the wind, and i actually had an actuator get bent...tho i can't recall if it was just from the force of the wind of if it got jambed up from turning too far.

rossw

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Re: I'm TRACKING!
« Reply #27 on: August 25, 2011, 05:58:27 PM »
anyway, i was making some sketches and maybe i can't seasonally adjust a traxle as easy as i thought i could...+/- 15 degrees is a fair amount.

Thats what I found too. It sounds easy. Right up until you actually make it....


Quote
if i put them in 2 rows, 1 in front north and 2 behind staggered east and west, the 2 in the back would be quite far apart i think.  i mean, they will each be 10' wide, so the 2 back ones would be at least 15' apart by the time i leave some room for them to clear the north array.  what is the rule of thumb for north to south spacing?

There's no "rule of thumb". It's just maths. You need to work out the difference in heights (if any). You need to find the lowest elevation of the sun in winter at midday. That tells you the ideal angle for your array on that day. With that angle, and the physical dimension of your panel, calculate (or draw, to scale) a line from the sun, past the top of your array. That shows you the shaddow line as it falls behind the array.
Now, calculate where the BOTTOM of the array behind it is (again, from the angle of the array and the size of it, and its mounting height), adjust for any ground level difference. If the rear panel falls in the shaddow area you figured above, its too close.  :)

As summer aproaches, the panels get more horizontal, and the sun gets higher, so it ceases to be a problem.

East-west alignment is done similarly, but I think you will find 15' is far too close.

As much as I'd like to have mine north-south, I too was forced to go east-west. I have them 8 metres (25') apart but still get significant shading at different times of the year.


rossw

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Re: I'm TRACKING!
« Reply #28 on: August 25, 2011, 06:43:58 PM »
If you look at my back array, it has a big chunk of concrete poured on the surface. I hand-dug the hole to about 18" and poured in a couple bags of quickcrete, but it was wobbling in the wind. So I framed it up with 2x6's and poured a slab around the pole. 

I should probably confess I had a similar problem.

My posts were dug 3' deep and 1' diameter with a hand post hole digger. The posts are about 3.5" square gal steel and quite strong.
After several weeks of continuous rain, we had a reasonable storm with substantial gusts - at a time when my panels were vertical (dusk).
The wind didn't just blow - it screwed around from all directions. The fact that the ground was fill (mostly clay), and soaking wet meant that the arrays were not sufficiently attached to the ground...



Here's looking at the ground around one:


Once things had dried out a bit, I used a winch to pull each array back square, poured concrete down the holes, compacted the clay around the top, then attached some diagonal bracing to the posts, welded reinforcing mesh to the legs, cleared out an area and poured a modest slab around the base. The idea is that it will partly help stop the ground getting so soggy, and if the slab is keyed to the post - wind trying to tip the post over will need to lift one side of the slab (hard), but push the other side into the ground (much harder!). So far, we've had winds over 100kmh and no sign of any movement whatsoever.





defed

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Re: I'm TRACKING!
« Reply #29 on: August 25, 2011, 07:42:39 PM »
well, i need to decide how i am going to situate them so i can get my combiner box situated...then i can at least hook up my 4 panels on the test stand.  i think i'm just as far away from deciding as i was before!

if you had to choose one as more important...would you have seasonal adjustment or tracking?  it appears if i only track, a traxle would be ideal (no shading of/from other racks).  if i wanted seasonal, single poles would be easier and shading wouldn't be as much an issue if not tracking.  i wonder if i had the 3 single poles in a triangular fashion, i could maybe limit the tracking angles to reduce shading.  if i am picturing it correctly, the most shading would occur during tracking when the arrays are tilted further (putting one side of the array high into the air).  fixed arrays seem as if they could be closer w/ less shading than trackers.

defed

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Re: I'm TRACKING!
« Reply #30 on: August 25, 2011, 07:48:15 PM »
in regards to your foundations....that's impressive to hold up to those winds w/ such a small amount of concrete.  even with that extra pad on the top, that's not a huge amount of weight/area.

i found one chart of recommended pole and footer sizes.  for 90 sq ft, they suggest 48" - 60" deep, 24" - 30" diameter, to support a 6" pole that extends 60" - 84" above the ground.  that too seems awfully light to me.  48" deep by 36" diameter is 1 yd...their recommendation is less than that.

rossw

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Re: I'm TRACKING!
« Reply #31 on: August 25, 2011, 08:19:26 PM »
if you had to choose one as more important...would you have seasonal adjustment or tracking?

Depends on your application.

Here's my "seasonal-only" adjustment array:



The east-west tracking gives a SUBSTANTIAL increase in usable watt-hours per day.
Seasonal adjustment lets you get 10% or so more than a fixed array at the midpoint.

Pure bang-for-buck, tracking gives much more benefit, but there's a lot more complexity to the mechanics.

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if i wanted seasonal, single poles would be easier and shading wouldn't be as much an issue if not tracking. 
See above photos.

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i wonder if i had the 3 single poles in a triangular fashion, i could maybe limit the tracking angles to reduce shading.  if i am picturing it correctly, the most shading would occur during tracking when the arrays are tilted further (putting one side of the array high into the air).  fixed arrays seem as if they could be closer w/ less shading than trackers.
Yes, and you could fiddle around with combinations of tilt, and different tilt on the front vs back array and all sorts of things to eek out a few extra watts.

If you haven't already done so, SERIOUSLY consider a MPPT charge controller.

defed

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Re: I'm TRACKING!
« Reply #32 on: August 25, 2011, 08:25:44 PM »
your non-tracking rack looks like something i had in mind before.  i thought i had a way to track, make them tilt like a window shutter, but then realized that they would have to be too far apart to avoid shading each other.

i've already got an mppt, and i wasn't planning on tracking right away (need to get some stuff up NOW!), but i would like to make sure i CAN when i want to.

been looking for a sun angle chart by season by location...i think i have one for solar noon that i used to find the best spot...maybe that has the info i need now that i think about it.