Solar Tracking

[kalakoa]

Amps harvested, as reported by charge controller, with a dummy load larger than the panel output.

Similar real-world results from the installed array: full-sun peak harvest is the same year-round.

Yes, I was a little surprised.

[Wao nahele kane]

Mppt controllers inherently alter and limit the power output and cant be used to make the appropriate measurements or demonstrate the adverse effects for a tilt angle test. Try putting a DC fan on the thin film cell and then do a tilt angle test... the fan will immediately respond to the effect.



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[kalakoa]

Inductive and/or capacitive properties of the fan contribute to the noise; I used a purely resistive load, but a truly "scientific" test would require substantially more instrumentation.

I would still rather not maintain small moving parts, especially when oversizing the array to compensate for "local weather conditions", more so at this latitude.

[Wao nahele kane]

In any case your system appears to be adequate all around and your demands haven't reached a point where they tax your system so yes... you'll not notice a seasonal change in power charge readings on your charge controller. Be thankful for that, most people use inadequate setups and run their generators frequently. I made the mistake of adding a chest freezer onto our system atop our already load of a fridge etc. before I deployed all 20 of our panels. Now I'm scrambling to get my tracker made so I can pull the 12 panels off my shipping container and add the other 8 inside the shipping container not yet used that have been waiting 3+ years to go into service.

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[Wao nahele kane]

We've been running our generator nearly once every 5 days the past couple months to compensate and I hate the sound of that damn thing running for 5-6 hours straight. How people can cope with that nightly or what have you is beyond me.

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[MarkP]

These were the deciding factors for me:

1. Long skinny flat roof free of any shading.
2. Got plenty of rails and clips to secure panels directly against roof for a very good price.
3. Roof is pointing in more or less the right direction and has an acceptable slope.

Since I lucked into the cheap attachment hardware and can make it work, any sort of adjustable mount system would mean taking three steps back for one step forward. That's just me though. I do like the idea of 2 or 3 banks facing SE, S, and NE. As it is I have sort of backed myself into a corner design-wise. Luckily it is working for me.

Meant SE, S, and SW of course.

[kander]

I built a tracking controller that positioned the panels to track the sun based on physical location/date/time of where the sun should be. It contains accelerometer/Ethernet/panel thermometer/DC amperage sensor. Likely using the same type of algorithm you are using in your mega board.

Anyway long story short.

Modern solar panels have glass on them that allows up to 30degrees of incident angle before power drops. With an AZ-EL tracker you can nearly double your average sunlight hours per region.

considering an economical 6 panel (600W) tracker the extra cost of the hardware was about 25% savings over adding extra panels and the cost of higher output grid tie inverters.

both fixed and tracking require cleaning. tracking has a lot more headache with linear actuators. I can only imagine how long those wont last in the most conditions of Hawaii.

[Wao nahele kane]

Kander,

"tracking has a lot more headache with linear actuators. I can only imagine how long those wont last in the most conditions of Hawaii."
You are correct, basic linear actuators won't hold up here in Hawaii. Be they gate openers or be it a worse scenario installed on a tracker, angled and exposed all around. The actuator on my driveway gate crapped out within its first 3 years of service and I had to replace some internal components. Proper sealing simply isn't feasible for a tracker application.

That's what my original question was aimed at, the average power increases. I knew this region would show better than 1.5X increases but wasn't sure how much more, 2x sounds reasonable although I based my original calculations on a 1.5X increase. The more, the merrier.

I'm going to start with Gabriel's algorithm from http://cerebralmeltdown.com and work from there. I'm not yet literate in the more current programing languages and for that matter the whole digital electronics world has changed leaps and bounds since the late 80's when I did my electronics study. All the things available today were mere pipe-dreams back then. So building the whole thing from scratch has demanded some time just to catch up the modern changes, brushless steppers, driver controllers, breakout boards and microcontrollers, etc.







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[kander]

yea I ran the tracker for over a year, and the average power output was 2x what the fixed panels would crank out over the day. Its algorithm based. Hence the need for accelerometers to tell what direction the panels were pointing in the sky. only used LDR's to verify the math was correct they were pointing at the brightest part of the sky.

What we discovered is that during cloudy days the brightest spot in the sky was sometimes not the sun. I an thinking of building a simpler more cost effective LDR tracker and compare the outputs between the two. The LDR will also track the moon which will produce a little bit of power at night.

I manufactured a polar mount for AZ-EL. your size of panel array is going to need to have some huge motors on it to withstand 90+MPH survival. I figured smaller arrays would work better for wind/snow/ice survival.

Im sure you will have a blast using the mega controller IC, Its actually what I based my controller on. I might consider an eyeball to eyeball meeting with you later this month and perhaps share some of the code and design specs.

[Wao nahele kane]

Kander,
Wind force: the steppers I'm using are NEMA 42 with the azimuth stepper at 32Nm torque into a 62:1 slewing drive (Net 1984Nm/1464Lbf drive torque, self locking). The elevation stepper is 22Nm torque into a 61:1 slewing drive (1342Nm/990Lbf drive torque, self locking). If we get a 90mph wind, the finished system will be in wind parking mode pointing straight up, I'll be building an analogue anemometer circuit switch for that add on, though currently there's already a manual switch for that purpose.

As per keeping track of the actual produced positions per sub cycle, the stepper should suffice (though I wont use it for this application; there's a potential of .036 seconds accuracy within the 40,000 subdivisions of the driver and that option would be better suited for telescope tracking or CNC mill use) but just the same I'm considering encoders mounted on the back of the worm screws on the slewing drives as check counters but I'm not yet sure about the additional programing space in the Mega (should be enough space but not certain yet). I don't have a clear vertical axis way for an encoder inside the pedestal because I'm installing an interior slip ring in the frame to transfer DC power output and AC input for unimpeded azimuth rotation, thus end mounts on the worm screws would be the most effective location for verifying stepper counts with encoders.

The LDR is a good idea and I've been considering implementing that also, will need to verify the practicality first but I've extra components for testing etc. so I can add the additional bells and whistles to the system down the road. As per moonlight power harvesting; I doubt there's enough harvested energy to compensate for the power consumed to drive the tracker, much better off adding a VAWT instead with a custom made neodymium generator for evening energy production (someday) Sure... would like to meet up sometime.

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