An interesting solar project..

[solarman]

Having recently returned from a solar project in Goa, I found myself like many others, "grounded"
with time on my hands from the consequences of the COVID-19 virus, I'm semi-retired, so I was thinking of
ways to occupy my spare time and decided to resurrect an old project from some 30+ years ago.
This is a solar tracker with a difference. the design is based on a 3 support gimbal assembly
much like a tripod. each support arm is a linear actuator attached to a ball joint assembly to a platform.
hence, by extending or retracting each arm a certan distance the
top platform ( a solar panel ) can be adjusted to point in any direction.
My eldest grandson ( 15 ) who is mathematically adept, also expressed an interest in this project, so he will
now have the chance to learn some interesting disciplines such as motor control, advanced math, software, mechanics
and of course solar engineering..

I decided to make the project somewhat ambitious, just for the fun of it..

the unit will be semi-autonomous, the concept is to have the unit deploy the tracker(s) on an RV
with little to no intervention from the user in that the tracker logic will determine the RV's location from
a GPS unit, the orientation from a compass module and then set the panel's asimuth and elevation automatically
by computing the sun's position. I have a collection of various software ( thanks to NASA and NREL ) that does the calculations.
this will be incorporated into the motor control software that we will write.

this is at the moment just a pure educational exercise, but if it is economically feasable, I may
attempt to market this, i have seen nothing like it for an RV, the major challenges are of course cost and space.
i'll update with pictures and posts in due course..

 

[msw3113]

Dang.  Though I suspect most of it will be well past my comprehension this sounds like a fascinating project.  As time and opportunity allows please do post your progress. 

 

[sadixon49]

Sounds like a great project.

 

[Ernie n Tara]

Sounds like a really fun project. I'd refine your estimate of the principal difficulties to being MECHANICAL STIFFNESS and STRENGTH plus height.  Given that this is not brain surgery, I'd imagine that high precision in azimuth or elevation is not super critical (a few degrees off will have minor impact). I'd suggest you consider a central pivot point (ball mount?), and three cable positioners. Then the height may be limited to that required by the maximum angles and size of the solar panel. It may then be reasonable to latch the corners down for travel.

Similarly, the GPS approach may be unnecessarily complex when the unit starts out known to be level and fully retracted. The electronic compass and a gyroscope chip combined with a simple azimuth table (determines approximately where the sun will be found) may be used to control positioning both during scan and peaking by monitoring panel output.

I'll leave my comments there and apologize for my impertinence in making these suggestions. In any event I'll be following your project with interest.

Ernie

 

[Kevin Means]

Coincidentally, the image below is a device that we?ve been developing and testing for about a year. It?s an autonomous solar tracker for RV rooftops, with an auto-stow/auto-lock feature in both azimuth and elevation. (It was patented about two years ago) The device in the picture has a 100 watt panel on it for testing, but it has been reliably tilting a 45 lbs residential panel for a couple of months now. That may be overkill, because when it comes right down to it, our research has shown that there aren?t many RVs that have enough room on their roofs to rotate a panel that large.

The device itself is four inches tall, rotates 360 degrees and has its own circuitry to track the sun. We evaluated SA and tracking with GPS but found it more complex and less effective than actual solar tracking - depending on conditions. We stumbled across other advantages of direct solar tracking too.

We?re currently in talks with a US manufacturer to build them for us, because demand for this device, and the original SolaRVector system has outpaced our ability to build them.

Kev

 

[solarman]

Coincidentally, the image below is a device that we?ve been developing and testing for about a year. It?s an autonomous solar tracker for RV rooftops, with an auto-stow/auto-lock feature in both azimuth and elevation. (It was patented about two years ago) The device in the picture has a 100 watt panel on it for testing, but it has been reliably tilting a 45 lbs residential panel for a couple of months now. That may be overkill, because when it comes right down to it, our research has shown that there aren?t many RVs that have enough room on their roofs to rotate a panel that large.

The device itself is four inches tall, rotates 360 degrees and has its own circuitry to track the sun. We evaluated SA and tracking with GPS but found it more complex and less effective than actual solar tracking - depending on conditions. We stumbled across other advantages of direct solar tracking too.

We?re currently in talks with a US manufacturer to build them for us, because demand for this device, and the original SolaRVector system has outpaced our ability to build them.

Kev

yes, space is a premium on a rooftop, always obstacles to bump into, this particular design i have may alleviate some of those issues.

In compiling a specification for this project i did consider various panel sizes and concluded that a square format panel might be a better
solution for an RV rooftop in a tracking application rather that the typical rectangular format.

As far as tracking performance, there is no difference ( or should not be ) in panel output between optical servo or software computed methods.
the acceptance range on a typical panel is in the order of 10 degrees, i have measured panel outputs at various degrees of error from the ideal
and the delta in this range is so small to be relevant.

Interesting, I'm surprised you can patent what is basically 20 year or older old prior art.. hmm...
still, i'm glad you have identified and are supplying a market, i would not have thought there was really any demand for
trackers, but having said that, I have not done any market research in the RV field either !.

Off grid we have all but abandoned trackers in small ( < 20 KW ) systems, it's far more cost effective ( especially maintenance wise )
to just add extra panels in different planes to compensate. sadly it's not possible on an RV.

I would agree with your statement on complexity, GPS and all the extra subsystems are indeed more complex, this project is really intended for
my grandson's education, however, with the abundance of micro computing solutions and low cost electronics these days, it might be economical
enough to market.. we shall see...

 

[solarman]

Well, here is a small update to the project..

Despite the covid menace, we are moving along at a reasonable pace, my grandson does however have asthma, his mother is a little too protective
so much so that most of our conversations are video chats.. this has slowed things a little, but we are making good progress.
he now has an understanding of basic electronics and is experimenting and learning how to control motors. I setup some hardware for him so he could
experiment and he is having fun.. that's the main thing..

I gave him quite a few exercises to work through, that should occupy him while i continue on the hardware drawings etc..

 

[Mark_K5LXP]

I have a friend that's a "solar nut", had an off grid house since back in the '70's long before it was as inexpensive or plug and play as it is today.

He was forever messing with a servo driven heliostats and even had a few really impressive examples.  But the ones on his production solar farm were passive.  A balanced frame that had tubes of what I think was freon that were shaded such when the sun hit them at an angle the freon would gas, move to the cooler tank on the other side, become heavier, and tip the frame.  As the sun moves across the sky so would the panels.  I thought this was pretty cool.  No moving parts, no electronics, no calibration, nothing to wear out.  I'm not sure how you get much better than this for sun tracking panels.  I totally get the technical challenge here though, much can be learned in a number of disciplines by even just building up a few prototypes.

Mark B.
Albuquerque, NM