Author Topic: My next brain fart  (Read 3892 times)

0 Members and 1 Guest are viewing this topic.

Madscientist267

  • Hero Member
  • *****
  • Posts: 1181
  • Country: us
  • Uh oh. Now what have I done?
My next brain fart
« on: April 11, 2011, 07:08:01 PM »
Actually I think this might work rather well... :)

So, I'm looking into cheap (key word) means of automatic tracking and in the midst, came up with one of them retro-saves...  ::)

The fan idea wasn't exactly the best... It helps temp wise, but I'm not sure to what degree (heh get it?) because I don't have an IR thermo. Heat is very evident in the exhaust, although not more than luke-warm-ish in the best of sun... The cells are dropping but I can't tell how far... and if there's output gratuity, I can't find it. :(

However, it got me to thinking... Why not power the tracker with the aux panel (which was brought up) but add a battery, dump the excess to the fans, and save my little mishap for one of these here stories.  ;D

And, I'd have a small 'reserve' available to me, should I need it...  8)

It kinda feeds into the next part of this...

I set up a rinkydink solar meter using an old button cell tester and a yard light panel. Just so happens that ~1A of buck output coincides with the very onset of full inflection (repulsion type meter). This was moderate overcast. Not bad... IF -

I tipped the panels and pointed them straight up at the sky. Incident light apparently isn't always best...  ???

So long story less long, considering adding a brain to this thing to tell it that if the average of the sky is better than any one direction, use it.

The idea would involve a rather goofy mod to 'reverse' a 70s fiber lamp (funnelled to a CDS cell), inside some kind of clear globe. There would be two CDS cells, to tell the difference between the combined average sky and the incident light value. This would be up above and in addition to the sensors required for the 'existing' XYZ tracking device.

It would also have hysteresis to prevent unnecessary hunting, maybe a couple of minutes worth before heading for a decision. [Probably integrate this into the H bridges actually... ?  * for me, not you :)]

Maybe, maybe not.

Besides, cooling never hurt anything...  ::)

Steve


The size of the project matters not.
How much magic smoke it contains does !

JW

  • Development Manager
  • Super Hero Member Plus
  • *****
  • Posts: 4020
  • Country: us
    • Flashsteam.com
Re: My next brain fart
« Reply #1 on: April 11, 2011, 10:00:37 PM »
The only thing im curious about, and dont hear about in the decription, is some sort of "pointer" casting a shadow on the photo transistors... I have even heard about LEDs being substituted for photo transistors with other attempts, that dont involve cooling, my opinion is that if the fans are there to control enviromental conditions under solar panels (photo-volt) its probably a good idea environmental-wise verse efficiency-wise.

JW

Madscientist267

  • Hero Member
  • *****
  • Posts: 1181
  • Country: us
  • Uh oh. Now what have I done?
Re: My next brain fart
« Reply #2 on: April 12, 2011, 09:02:25 AM »
The two CDS cells mentioned actually don't need shadowing; they're not for tracking in the traditional sense. They only compare the sky's 'quality to quantity' so to speak.

The one with the fiber optic strands will see the sky average, and is mounted statically to the frame (does not track the sun). The idea there is that no matter where the sun is in the sky, the light falling on the sensor will be the same. This sensor is primarily just a reference for the incidental sensor, allowing for the differences between night, dawn, mid-day, and dusk to prevent false 'assumptions' by the brain. Since absorption and scatter will also have an effect on the light reaching this sensor (during cloud cover), there would be a 'reach for the sky' threshold that must be met before the unit would decide that straight up is an option.

The incidental sensor would track with the panels, and face in the same direction, to measure the light hitting the panel at it's current position. If clouds roll in, this sensor will more closely match the average sensor, telling the unit to reach for the sky rather than sit in the direction it is currently sitting.

When the sun is directly visible once again, the average sensor will see more light, and tell the unit to return to where it came from before the 'panic'. From there, the XYZ sensors take over, and zero in on the sun.

These two sensors would be able to override the XYZ tracking sensors, which would be shadowed, as always. There's not much (if anything) to change about the 'standard' part of the tracker.

The fans were, and will continue to be, a supplemental cooling system for the main panels. There isn't much gain in terms of output (I'm sure there is, but not really measurable), but keeping the temperature down will help extend their life. It just so happens that the fans can readily be used as the dump load for the auxiliary power system, so I'm leaving them in place, but will just be modifying their behavior and purpose.

Steve
The size of the project matters not.
How much magic smoke it contains does !

DamonHD

  • Administrator
  • Super Hero Member Plus
  • *****
  • Posts: 4125
  • Country: gb
    • Earth Notes
Re: My next brain fart
« Reply #3 on: April 12, 2011, 03:52:28 PM »
Several patents claim that in overcast conditions, pointing straight up is better than trying to track.

And in that spirit I have some extra "winter" panels nearly horizontal.

Here's some more: http://www.earth.org.uk/note-on-solar-PV-for-diffuse-light.html

Rgds

Damon
Podcast: https://www.earth.org.uk/SECTION_podcast.html

@DamonHD@mastodon.social

Madscientist267

  • Hero Member
  • *****
  • Posts: 1181
  • Country: us
  • Uh oh. Now what have I done?
Re: My next brain fart
« Reply #4 on: April 12, 2011, 05:17:27 PM »
I can attest that under 'fair' overcast skies, I was able to double my current by pointing straight up, as opposed to pointing in the direction that the sun 'was'. As long as the clouds still appear brighter than a light grey, there is usable power to be had.

It's next to pointless though for anything darker than that. Power rapidly falls off to <10% of the above measurements, so there's no point in seeking it.

I don't this will be an issue since I plan on making it sit and wait when 'uncertain', so as to save as much tracker battery as possible. It's not like the entire sky can spontaneously turn dark grey at once...  ;)

Once it moves to the horizontal position, it won't move unless it registers incidental light directly from the sun. A darker sky will just make it stay put.

The biggest challenge is a full axis tracker on a portable mount! LOL

Steve



The size of the project matters not.
How much magic smoke it contains does !