Solar/Sun tracking system DIY?

[McIntoshUSA]

This at first glance looks ingenious. I guess it would work. I wonder how it could be setup on a Sailboat? (For use when anchored or docked) Any Ideas? https://www.youtube.com/watch?v=HkhVomoD47g I am guessing he used an electric motor with forward and reverse. One side of his small electrical panels hook up to forward and the other side hooked up to reverse. Seems simple?

 

[Brian D]

The same concept is used to track satellites on cruise ships. The motors/controller must be connected to a GPS to get your Lat/Long/Heading. Then, there needs to be software to determine the Az/El of the sun at any given time during the day. All this information controls the tracker so no matter what point of sail or heading, the controller will always have the panel(s) pointing at the sun (when visible). At sunset one would want the panels to stop tracking.

In a nut shell, that is all there is too it. It can be done very easily. All one needs is a motor for azimuth and a motor for elevation. That can come from a telescope that tracks stars. You already have the GPS with heading. Just need a software package to calculate az/el of the sun.

 

[SailorTom]

Brian D said about all there is to it! Happens I built a solar tracker using stepper motors as a programming project at VT many, many years ago using assembly language!
I'm sure today any 13year old computer guy/gal could do it an an half hour

 

[Bill Roosa]

This is one of the overly complicated tracking devices. You can do the same thing with 5 LEDs and an duel opamp.
Do it in altitude and azimuth and it would work on a boat
AND
you don't need a GPS for lat long as it just stays pointed at the strongest light source. At night it would track a flash light or street light nearby.
http://solartracker.greenwatts.info/solar_tracker_cds_new_theory.htm

 

[capta]

If you are thinking of something like this on a boat, the whole thing seems pretty energy inefficient on a boat at anchor. What energy you might gain by always being lined up directly on the sun would be more than consumed in keeping that alignment as the boat swings on her anchor.
Also the strength of the mechanism would need to be considerably more than a shore based unit, if one takes into account the torque of the boat's movement underway.
We find that our panels are trickle charging by noon anyway on most days, so there would be little advantage to this set up. I think practically speaking, the money would be much better spent towards the purchase of a quality windgen, to take up whatever slack in the solar panels' charging .

 

[Bill Roosa]

So what do you base your assertions on capta?
the differance between horizontal no tracking and two axis tracking is pretty amazing. I can show the math (takes a trip down calculus lain though) but 54% increase in production gives you a lot of room to run a small motor. I would note that you only need two small motors. a well balanced design on good bearings is not going to be that hard to move around. The tracker takes almost no (>> 1 amp) current.

 

[capta]

So what do you base your assertions on capta?
the differance between horizontal no tracking and two axis tracking is pretty amazing. I can show the math (takes a trip down calculus lain though) but 54% increase in production gives you a lot of room to run a small motor. I would note that you only need two small motors. a well balanced design on good bearings is not going to be that hard to move around. The tracker takes almost no (>> 1 amp) current.

I think you are underestimating the power necessary to move your array at the speed most small craft swing and the strength of the system (weight) to keep it attached to a moving vessel. For the last week or so our winds have been running 18 knots to 23 knots with 30+ knot gusts and our swinging is considerable and swift.
But hey, go for it and when your system has finished charging at 11AM (as mine does without the added 54% efficiency) and dropped back to trickle charge, you can watch it maintain the batteries as it needlessly expends energy following the sun around. For my part, I think simple, corrosion and maintenance free, is the preferable way to go.

 

[justsomeguy]

Agreed, capta.

 

[Delezynski]

Agreed, capta,

What a lot of people don't understand is a boat at anchor and what the ocean environment can do to mechanisms.
As I am fond of saying, The difference between theory and reality, is reality!

Greg

 

[Brian D]

Although Capta has a valid point, the key to keeping power requirements down is counter balance. Again, let me use the satellite dish on a cruise ship analogy.

First, the dish is in a radome so there is no outside forces such as wind to fight with the motors. However, cruise ships are not always in fair winds and following seas. They get beat up a bit. The antenna is designed with weights for balance and counter balance. If and when the dish is pointed at the satellite, no matter how much yawing, pitching, and rolling is going on, the dish remains locked on the satellite. The key is, as mentioned above, good bearings and well balanced.

If the solar panel were well balanced, it does not make any difference what the boat is doing under the panel. It will remain pointed at the sun. The motors are there to just make minor alignment changes.

Again, the key is "well balanced"!

As for the GPS, true, it might not be needed, but at least ones lat and long are required to make the calculations for sidereal tracking of any celestial body.

 

[trkarl]

As for the GPS, true, it might not be needed, but at least ones lat and long are required to make the calculations for sidereal tracking of any celestial body.

To calculate the tracking, yes. To track it using brightness differentials, no, there is no need for lat/long data.

Bill Roosa's link tracks using brightness differentials. Just add another circuit like this for height (leds mounted vertically with a blind between them), and your're done!

The whole point of this setup is that, if you don't already have solar panels, you can use a smaller solar panels with tracking to generate the same or similar amount of power as larger panels without tracking. Putting a tracking system on solar panels that already charge the batteries by noon is a waste of time/money.

Of course the tracking system would have to be built for rough weather/marine use, but may turn out to be a great idea because you get away with smaller panels.

 

[Bill Roosa]

I find it hard to believe that you can top off you banks by noon. Add a reefer and freezer to the loads and you can easily get 240 Ah / day. That means a 40 amp input from sunup to noon!!!!! not going to happen. So you need a 80+ amp panel working mostly between 0900 and 1200???? That would be a 1152 watt panel!!!
The deck space for that kind of panel is just not available on most boats. Even if you charge all day long you are not going to be able to support those kinds of loads with a non-tracking setup. Add a two axis tracker and get full output from 0700-1700 = 10 hours (versis the 5 planning hours for non-tracking) and you can half your panel size!!

 

[Ron20324]

I find it hard to believe that you can top off you banks by noon. Add a reefer and freezer to the loads and you can easily get 240 Ah / day. That means a 40 amp input from sunup to noon!!!!! not going to happen. So you need a 80+ amp panel working mostly between 0900 and 1200???? That would be a 1152 watt panel!!! ... Even if you charge all day long you are not going to be able to support those kinds of loads with a non-tracking setup. Add a two axis tracker and get full output from 0700-1700 = 10 hours ...!!

If CAPTA says that's the way his boat functions, then I don't believe it is good forum etiquette to infer he is lying by making assupmtions and trying to prove his statement is false. His boat, he ought to know, let it go.

 

[walt]

To make the panel adjust for boat heeling gets complicated.. but for example just having the panel track the sun on a mooring would just require setting the panel angle based on the time of year and just letting the control system adjust the azimuth (horizontal angle).

I have a 40 watt solar panel that I can adjust angle and azimuth (manually) and a few years ago did some measurements in February in Arizona. I think that the lower the sun is in the sky, the more you likely get from having the panel track the sun and in my case, the sun would be somewhat low in the sky. I put the measurements into a simple spread sheet to see about what I would get if the panel did track the sun. The numbers are just ballpark..

In this simulation, I also added in MPPT with a 15% gain. edit.. that is hard to read but the tracking panel would have about a 38 percent gain over a panel looking straight up.

I think you are underestimating the power necessary to move your array at the speed most small craft swing

Maybe you can show your numbers but I don’t think the power to move the panel would be significant compared to the gain. I think for a 100 watt panel, it might take .2 amps (which would be 2.4 watts at 12 volts) with a 25% duty cycle to move the panel. Over a seven hour period, that would be only .35 amp hours.

Using a rough number of maybe 25 amp hours from that panel for the same 7 hours, by tracking the sun and using the 38% gain, you increased the output by 9.5 amp hours.

I.e., you used .35 amp hours to net 9.5 amp hours.. Well.. that is a significant gain.

Regardless, I’m also of the impression that this just would not be worth doing on a sailboat especially if used mostly during the sumer when the sun is high in the sky. MPPT with a 3% loss in the wires to the panel and 1% loss to the battery is much simpler way to get easy gain. I think Maine Sail was getting near 19% in the North East in May or June (cooler temps).

Also, simply minimizing shading nets big gains. Which leads to me to wonder... how much does a single bird poop dropping reduce a solar panel output? Or multiple droppings?

 

[Brian D]

... how much does a single bird poop dropping reduce a solar panel output? Or multiple droppings?

Before one can answer that, one must first ask... "What is the airspeed velocity of an unladen swallow?" :naughty:

 

[uncledom]

Before one can answer that, one must first ask... "What is the airspeed velocity of an unladen swallow?" :naughty:

African or European?