Design Con 2015
Breaking News
Comments
Tom Murphy
User Rank
Blogger
Shady Business
Tom Murphy   7/23/2013 6:06:43 PM
NO RATINGS
I wonder, instead of using the shade, wouldn't it have been better to simple put a light-absorbing filter over the photovoltaic cells?  The shade would shift in angle, exposing more of one cell than the other, while a filter would keep them even -- replicating Florida in Arizona. 

Caleb Kraft
User Rank
Blogger
Re: Shady Business
Caleb Kraft   7/23/2013 6:15:44 PM
NO RATINGS
The entire point was to make them uneven so that the array would shift to put them back in an even state. Without the shade, both panels reached saturation at all times. The shade gives a mechanical means of increasing the disparity between the two. 

Tom Murphy
User Rank
Blogger
Re: Shady Business
Tom Murphy   7/23/2013 6:22:00 PM
NO RATINGS
I know that's what he meant, Caleb, but I was confused by this part:

The MBED reads voltage from two small photovoltaic cells placed at right angles to each other. It rotates until the voltages on the two panels match. However, Davis found that this did not work in the Arizona sun as well as it did on his Florida workbench. The sun was too bright, and the difference between the panels was too minimal at any angle.

 

That made me wonder, if the Arizona sun was too bright, then why not make it less bright with a filtering lens? Wouldn't an opaque shade cast a longer and longer shadow as it tilts, thereby throwing off the direction more and more?  I'm not getting that part.

Caleb Kraft
User Rank
Blogger
Re: Shady Business
Caleb Kraft   7/23/2013 6:54:29 PM
NO RATINGS
Sorry, He was using a lightbulb on his workbench for testing which is much more directional than the sun (ar at least a smaller source in relation to the sensor)

Tom Murphy
User Rank
Blogger
Re: Shady Business
Tom Murphy   7/23/2013 7:06:07 PM
NO RATINGS
I get it. So the problem wasn't that the sun was brighter, but was more evenly distributed -- the distance from one side of the board wasn't any different from the other side. That makes sense. I'm still not sure how he keeps the increasing angle of the sun against the shade from increasingly throwing off the calibration, but I'll just accept the notion that he found a solution. Thanks!

Luis Sanchez
User Rank
Rookie
This reminds me of my school project
Luis Sanchez   7/23/2013 11:59:13 PM
NO RATINGS
We at school tried to do this almost same thing. But We were using a stepper motor and it was more of a simulation as we didn't have real solar panels. 

But, reading about this makes me question... how about using the same current that the solar panel yields as a measure or as the level to judge if the panel is receiving the light at the expected levels. Mmmm just by thinking on it I guess it would be more difficult as some variations are added to the system like the fact that the sunlight varies in the course of the day and also varies with the seasons. 

Thus, perhaps this is something to consider for using all that horse power in the MBED brain ... to make it able to get the weather info and from that define a range of sunlight intensity. Then wage that with some tables which model the expected intensity during the day and season and vuola! now you can spare some hardware and save some bucks! If it's mass produced then you'd be saving a lot of dollars man! 

There, first Feature Requirement for v 2.0 ;-)

Caleb Kraft
User Rank
Blogger
Re: This reminds me of my school project
Caleb Kraft   7/24/2013 12:08:09 AM
NO RATINGS
Yeah, a stray cloudy patch could put the system into a mode where it thought it was out of allignement (without some way to determine based on direction).


Some companies have abandoned flat panels because of these issues and gone to cylindrical ones with reflectors behind them. That is considerably more difficult in your home though.

Tom Murphy
User Rank
Blogger
Re: This reminds me of my school project
Tom Murphy   7/24/2013 11:45:59 AM
NO RATINGS
Good thoughts, Luis, and it made me think of another approach. Why not put a tube slightly greater than the diameter of the solar cell that would channel the maximum amount of sunlight when the tube is pointed directly at the sun? Then the rig could be calibrated to maintain the maximum voltage from the cell, which would keep it aimed at the sun.

Caleb Kraft
User Rank
Blogger
Re: This reminds me of my school project
Caleb Kraft   7/24/2013 11:58:30 AM
NO RATINGS
this is exactly what one company did recently. Instead of having rotating solar cells, they were cylindrical with a reflector below them that was also cylindrical. When done in a larger quantity this is much more efficient than rotating a flat panel (they claim). 

Here they are if you're curious. http://www.solyndra.com/technology-products/

wwbrown
User Rank
Rookie
Re: This reminds me of my school project
wwbrown   7/24/2013 12:34:48 PM
NO RATINGS
It is easy to calculate the position of the sun very accurately based on location and time.  I do not understand why an optimization algorithm is used when you could just calculate the position.  The MBED has an on board real time clock and the location could be input each time it was moved so a dedicated GOS unit on the tracker would not be required. 

An on GPS could easily be used if the designer thought the drift on the RTC was too great.  The location of the system could be read in from the GPS when started at a new location.  Measurements of the location could be read in for a pre-determined period and the location would then just be the average of those results, this would provide a better location.  Given the distances involved any location the GPS gave you would suffice anytime the GPS had a lock.

rick merritt
User Rank
Author
Tracking the sun and star
rick merritt   7/24/2013 8:48:03 AM
NO RATINGS
Now if Mike got together with the guy tracking satellites  (http://www.eetimes.com/author.asp?section_id=36&doc_id=1318979&)  they could collaborate on a system to track the sun and the stars ;-)

prabhakar_deosthali
User Rank
CEO
North-South tracking
prabhakar_deosthali   7/24/2013 10:34:29 AM
NO RATINGS
The way the correction has been applied to rotate the panels to get maximum sunlight thruout the day, a similar correction can be done to track the sun's north south movement during the year. This is especially required for the regions which are away from the equatorial regions.

Caleb Kraft
User Rank
Blogger
Re: North-South tracking
Caleb Kraft   7/24/2013 10:36:36 AM
NO RATINGS
Indeed. He talked about that a little bit, stating that he didn't need it at this point.

It seems like a linear actuator on the taller end of the base would achieve this pretty easily. 



Top Comments of the Week
Flash Poll
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
<b><a href=Betajet">

The Circle – The Future's Imperfect in the Present Tense
Betajet
Post a comment
The Circle, a satirical, dystopian novel published in 2013 by San Francisco-based writer Dave Eggers, is about a large, very powerful technology company that combines aspects of Google, ...

Max Maxfield

Recommended Reads From the Engineer's Bookshelf
Max Maxfield
2 comments
I'm not sure if I read more than most folks or not, but I do I know that I spend quite a lot of time reading. I hate to be idle, so I always have a book or two somewhere about my person -- ...

Martin Rowe

No 2014 Punkin Chunkin, What Will You Do?
Martin Rowe
2 comments
American Thanksgiving is next week, and while some people watch (American) football all day, the real competition on TV has become Punkin Chunkin. But there will be no Punkin Chunkin on TV ...

Rich Quinnell

Making the Grade in Industrial Design
Rich Quinnell
15 comments
As every developer knows, there are the paper specifications for a product design, and then there are the real requirements. The paper specs are dry, bland, and rigidly numeric, making ...

Special Video Section
The LT8640 is a 42V, 5A synchronous step-down regulator ...
The LTC2000 high-speed DAC has low noise and excellent ...
How do you protect the load and ensure output continues to ...
General-purpose DACs have applications in instrumentation, ...
Linear Technology demonstrates its latest measurement ...
10:29
Demos from Maxim Integrated at Electronica 2014 show ...
Bosch CEO Stefan Finkbeiner shows off latest combo and ...
STMicroelectronics demoed this simple gesture control ...
Keysight shows you what signals lurk in real-time at 510MHz ...
TE Connectivity's clear-plastic, full-size model car shows ...
Why culture makes Linear Tech a winner.
Recently formed Architects of Modern Power consortium ...
Specially modified Corvette C7 Stingray responds to ex Indy ...
Avago’s ACPL-K30T is the first solid-state driver qualified ...
NXP launches its line of multi-gate, multifunction, ...
Doug Bailey, VP of marketing at Power Integrations, gives a ...
See how to ease software bring-up with DesignWare IP ...
DesignWare IP Prototyping Kits enable fast software ...
This video explores the LT3086, a new member of our LDO+ ...
In today’s modern electronic systems, the need for power ...