Solar Tracker Project - Page 11

Xringer · 06-27-10, 02:20 PM

Quote:

Originally Posted by NiHaoMike

What about use a BEAM robotics circuit that does not require any batteries? Use bigger ratios so the motor can be smaller. Then design a circuit based on charging a capacitor from a small solar panel, then periodically discharging it through the motor in the right direction.

Actually, I've been thinking about getting rid of the battery.

The actuator motor doesn't use a lot of power, and if the sun is bright,
the little 10w PV can move the array.
So, If I was to stick another 10w PV up there, I think it would track,
anytime the sun was pretty bright.

But, the main drawback is the Go-Home after sunset mode.. It needs juice!

Xringer · 06-27-10, 02:31 PM

Quote:

Originally Posted by nibs

My newer panels are pretty good at making power on cloudy days, so it may pay.
A couple of years ago, there was a guy at Quartzsite AZ selling a beautifully made well engineered tracker for around $2,000 but at that price it was far cheaper (not as elegant) to just add another panel or two.

$2,000!! I assume that included at least 500 watts of PV in the package..

The landscape out in the boondocks of New England is dotted with old satellite dishes.
You can get them for free, 'Just take that eyesore out of my yard', many times.
Sell the aluminum and use the mount for your array. Now that PV is getting
cheaper, I'm pretty sure that you can put up a tracking starter array for less than 2k.
I'm not sure what I've sunk into the old mount, but it's around $1,500..

I'm pretty sure it's going to cost more as time goes by and I add items to it..
Ebay addict..

NiHaoMike · 06-27-10, 05:06 PM

Quote:

Originally Posted by Xringer

Actually, I've been thinking about getting rid of the battery.

The actuator motor doesn't use a lot of power, and if the sun is bright,
the little 10w PV can move the array.
So, If I was to stick another 10w PV up there, I think it would track,
anytime the sun was pretty bright.

But, the main drawback is the Go-Home after sunset mode.. It needs juice!

BEAM robotics is designed to be extremely efficient. At sunrise, the BEAM circuit would automatically position it back before there is much energy to extract. You could also add a circuit to switch in a battery only when it gets very dark.

Xringer · 06-27-10, 05:46 PM

Quote:

Originally Posted by NiHaoMike

BEAM robotics is designed to be extremely efficient. At sunrise, the BEAM circuit would automatically position it back before there is much energy to extract. You could also add a circuit to switch in a battery only when it gets very dark.

I just looked at BEAM robotics - Wikipedia, the free encyclopedia

And it sure sounds like what I've been doing.. Which is already working pretty well..

"This is a term that refers to a style of robotics that primarily uses simple analogue circuits, such as comparators, instead of a microprocessor in order to produce an unusually simple design (in comparison to traditional mobile robots) that trades flexibility for robustness and efficiency in performing the task for which it was designed."

"
1. Use the lowest number possible of electronic elements ("keep it simple")
2. Recycle and reuse technoscrap
3. Use radiant energy (such as solar power)
"

Yeah, that sounds like it alright..

nibs · 06-28-10, 09:48 AM

X - No the $2,000 did not include any pv panels. The unit operated by running a stepper motor at preset intervals. All the castings were aluminum and nicely finished, the unit was intended for RV use, so folded flat for travel. My design experience and knowledge of mechanical devices lead me to believe it was a very well done unit. The problem with it of course was that simply by adding another 200 watt panel for $500 +/- you could get just as much power without tracking. So economically it made no sense, however If I could have bought one for the bragging rights .........hmmmmmmm.

Xringer · 07-03-10, 09:50 AM

Quote:

Originally Posted by wilfor03

Appreciate the heads up on the LDR's and the heat....gonna try it and see what happens....gonna do some searching on the internet and see if/what other people have had problems with and how they may have fixed it. I'll keep ya posted......thanks Rich...............Bill

Okay Bill,
What's the good word on your tracker? Got it working yet?

Mine was great with the new LDRs, but yesterday it started acting up.
It was falling behind. The shadow stick showed me the tracker was lagging.
I checked the voltages on the LDRs and they weren't falling below the Ref.
So, I pulled the board, pulled the 10k pot (radio shack) and installed a 20k pot.
I increased the Ref voltage up from 1.23v to 1.5v and got it tracking,
but with relay chatter again.
It was a nice day, not too hot and the LDR head only 80F..

I think one of causes of the instability is the changing +12V supply.
When the motor comes on, it drops the voltage on the battery just slightly.
That drop, is noticed by the Solar charger and it comes on, placing a charge
voltage on the battery, which slightly Increases the +12V supply!

Of course this up&down of the +12V caused the Ref voltage to change just slightly.
And the LDR voltages jump up and down too..
What stays the same is the Sun, and it's effect on the LDRs.

I put a 47uf across the 12V input to the PCB, but no joy.

Tried adding some 0.1uf tantalum caps across the LDRs, hoping to slow
down the voltage changes. But I got back-n-forth motor oscillations again.
(Due to over-shoot & correction reverses).

I'm now thinking about adding a zener diode to the ref divider, to make
that voltage stay put..

I also found some really nice LDRs in my junkbox. They get down to
much lower resistance than the MTM LDRs.
In the sun, one went down to 25 ohms and other one stopped at 38 ohms.
The MTM LDRs are up around 100 ohms in bright sun..

Anyways, I reset the ref voltage to 1.35v this morning.. Maybe today it will work better.?.

Cheers,
Rich

wilfor03 · 07-03-10, 11:32 AM

Hey there Xringer......sorry for not posting for awhile. My board quit working on me! I troubleshot it down to one of the relays not latching (no movement). Got ahold of MTM and he sent me two relays AND another LM339 comparator. What a dude! All in one day!!! He's made a believer out of me with his "Customer Service" policy, eh? The board is working super great with the same clatter on the relays as before. Too bad he doesn't come up with some sort of Mosfet deal versus those relays. That would be a strong board then I think. I love it!!!

Sorry to hear you're still having those LDR problems. Mine mounted in the baby-food jar is doing great. Don't feel any heat whatsoever when I crawl up there and check it out. I'm running my tracker board off the same 12v supply I'm charging with the solar panels. Even when the sun goes down and I need to move the panels (for storms, whatever) I always have plenty of juice to do it with. Just ran a spare wire pair when I initially ran the wiring in the pipe. Sure glad I did that, too......anyhow, if I can help ya somehow, hollar down this way, okay? Bill

Xringer · 07-03-10, 12:43 PM

I somehow burned out a comparator a while back. It took a while with the voltmeter
to locate the stuck output line.
When your brain gets old, it takes awhile for logic errors to register..

Anyways, Radio Shack had two in stock, I got both of them..

I like the nice compact box you have for your tracker.. Very neat..

I'll bet your tracker supply voltage is very stable, coming from a large AH battery pack..

I've been thinking about that little Power Jumper on the PCB..
That's where you can insert 24V to run your motor..
So, I could connect my bouncing-baby-battery into that connection
and use a bit lower voltage to run the chip and replays..?.

Since the battery is always around 13v, maybe I could make a 10v regulator to drive the PCB..?

It would add some load to the battery at night, but that 10w PV would bring
it back up to par with a few minutes of good sunshine..

Edit: I think maybe I'm wrong here. A series regulator chip will add series resistance
to the PCB load, making it use less power..

Regulated voltage running the board has to be way better that what I have now.

http://www.ramsond.com/solarpanel/ra...specs2.jpg.jpg

wilfor03 · 07-03-10, 01:28 PM

Yup, having the great-constant 13.6vdc for the tracker and the actuator really makes things smooth here. The box where I have the board is my combiner/tracker board house. For once, when I was putting the system together, I thought about alot of junk and the outcome was pretty good IMHO. I was gonna try and just use one of the little 5w panels to run the tracker board and then thought if I needed to move this thing in the middle of the night, no-can-dooooo, so, this is what I came up with. The next one will be even better yet (LOL)
I don't think 13.6vdc is to much for the board (LM339/relays) cuz it has a pretty good fudge-factor built into it. I like having the 13.6vdc for the actuator motor (24vdc) because it runs soooooooooooooooo slow (just have relay chatter a bit), definitely won't overrun the target at that speed LOL........Bill

Xringer · 07-03-10, 02:12 PM

I'll bet anything between 10 and 14 volts would work for the board.
It's the motor that likes the higher voltages..

I was thinking of using 10v because it should be easy to build a 10V 1A regulator with 13.6 as a source.
I think the relays and comparator might even work using 9V too.
The goal of using a 10v regulator is to isolate the PCB from being directly connected
to the battery with it's motor loading & solar charger ups & downs..

07-03-10, 11:32 AM	#107
wilfor03 Lurking Renovator Join Date: Feb 2010 Posts: 29 Thanks: 1 Thanked 0 Times in 0 Posts	Hey there Xringer......sorry for not posting for awhile. My board quit working on me! I troubleshot it down to one of the relays not latching (no movement). Got ahold of MTM and he sent me two relays AND another LM339 comparator. What a dude! All in one day!!! He's made a believer out of me with his "Customer Service" policy, eh? The board is working super great with the same clatter on the relays as before. Too bad he doesn't come up with some sort of Mosfet deal versus those relays. That would be a strong board then I think. I love it!!! Sorry to hear you're still having those LDR problems. Mine mounted in the baby-food jar is doing great. Don't feel any heat whatsoever when I crawl up there and check it out. I'm running my tracker board off the same 12v supply I'm charging with the solar panels. Even when the sun goes down and I need to move the panels (for storms, whatever) I always have plenty of juice to do it with. Just ran a spare wire pair when I initially ran the wiring in the pipe. Sure glad I did that, too......anyhow, if I can help ya somehow, hollar down this way, okay? Bill Attached Thumbnails

07-03-10, 12:43 PM	#108
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I somehow burned out a comparator a while back. It took a while with the voltmeter to locate the stuck output line. When your brain gets old, it takes awhile for logic errors to register.. Anyways, Radio Shack had two in stock, I got both of them.. I like the nice compact box you have for your tracker.. Very neat.. I'll bet your tracker supply voltage is very stable, coming from a large AH battery pack.. I've been thinking about that little Power Jumper on the PCB.. That's where you can insert 24V to run your motor.. So, I could connect my bouncing-baby-battery into that connection and use a bit lower voltage to run the chip and replays..?. Since the battery is always around 13v, maybe I could make a 10v regulator to drive the PCB..? It would add some load to the battery at night, but that 10w PV would bring it back up to par with a few minutes of good sunshine.. Edit: I think maybe I'm wrong here. A series regulator chip will add series resistance to the PCB load, making it use less power.. Regulated voltage running the board has to be way better that what I have now. http://www.ramsond.com/solarpanel/ra...specs2.jpg.jpg Last edited by Xringer; 07-03-10 at 02:22 PM..

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06-28-10, 09:48 AM	#105
nibs Apprentice EcoRenovator Join Date: Jun 2010 Posts: 206 Thanks: 1 Thanked 18 Times in 17 Posts	X - No the $2,000 did not include any pv panels. The unit operated by running a stepper motor at preset intervals. All the castings were aluminum and nicely finished, the unit was intended for RV use, so folded flat for travel. My design experience and knowledge of mechanical devices lead me to believe it was a very well done unit. The problem with it of course was that simply by adding another 200 watt panel for $500 +/- you could get just as much power without tracking. So economically it made no sense, however If I could have bought one for the bragging rights .........hmmmmmmm.

07-03-10, 01:28 PM	#109
wilfor03 Lurking Renovator Join Date: Feb 2010 Posts: 29 Thanks: 1 Thanked 0 Times in 0 Posts	Yup, having the great-constant 13.6vdc for the tracker and the actuator really makes things smooth here. The box where I have the board is my combiner/tracker board house. For once, when I was putting the system together, I thought about alot of junk and the outcome was pretty good IMHO. I was gonna try and just use one of the little 5w panels to run the tracker board and then thought if I needed to move this thing in the middle of the night, no-can-dooooo, so, this is what I came up with. The next one will be even better yet (LOL) I don't think 13.6vdc is to much for the board (LM339/relays) cuz it has a pretty good fudge-factor built into it. I like having the 13.6vdc for the actuator motor (24vdc) because it runs soooooooooooooooo slow (just have relay chatter a bit), definitely won't overrun the target at that speed LOL........Bill

07-03-10, 02:12 PM	#110
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I'll bet anything between 10 and 14 volts would work for the board. It's the motor that likes the higher voltages.. I was thinking of using 10v because it should be easy to build a 10V 1A regulator with 13.6 as a source. I think the relays and comparator might even work using 9V too. The goal of using a 10v regulator is to isolate the PCB from being directly connected to the battery with it's motor loading & solar charger ups & downs..