In the past few years, the price-per-watt for solar panels has dropped dramatically. This has led to a number of downstream effects beyond simple cost savings. For example, many commercial solar farms have found that it’s now cheaper to install a larger number of panels in fixed positions, rather than accepting the extra cost, maintenance, and complexity of a smaller number panels that use solar tracking to make up the difference. But although this practice is fading for large-scale power production, there are still some niche uses for solar tracking. Like [Fabian], if you need to maximize power production with a certain area or a small number of panels you’ll wan to to build a solar tracker.
[Fabian]’s system is based on a linear actuator which can tilt one to four panels (depending on size) in one axis only. This system is an elevation tracker, which is the orientation generally with respect to latitude, with a larger elevation angle needed in the winter and a lower angle in the summer. [Fabian] also designs these to be used in places like balconies where this axis can be more easily adjusted. The actuator is controlled with an ESP32 which, when paired with a GPS receiver, can automatically determine the sun’s position for a given time of day and adjust the orientation of the panel to provide an ideal elevation angle on a second-by-second basis. The ESP32 also allows seamless integration with home automation systems like SmartHome as well.
Although this system only tracks the sun in one axis right now, [Fabian] is working on support for a second axis which mounts the entire array on a rotating table similar to an automatic Lazy Susan. This version also includes a solar tracking sensor which measures solar irradiance in the direction the panel faces to verify that the orientation of the panel is maximizing power output for a given amount of sunlight. Tracking the sun in two axes can be a complicated problem to solve, but some solutions we’ve seen don’t involve any GPS, programming, or even control electronics at all.
BTW If the “single axis” just happens to be parallel to your latitude then you will never be more that 23.44 degrees out (obliquity of the ecliptic). Then if you have a manual jack screw that you turn perhaps once a week you will never be more than 1.4 degrees out.
Cheaper and better to just put a second panel up.
Moving parts suck.
Indeed. Even 30 years ago when solar panels were much more expensive solar trackers were not used much. The combination of the extra complexity, extra weight to make the moving thing strong enough to resist strong winds, water ingress for electronics and bearings, wear of motors, energy consumption of motors are all causes for reduced reliability and increase maintenance cost, which further reduces the benefit for such system.
And even if available room is limited, most solar trackers still need empty room around it, to prevent the systems from bumping into each other. With stationary panels the whole available area can be covered.
To make a video like this interesting, you would need to make a comparison of total cost of installation and maintenance (including man hours) for both systems over a 10+ years lifespan.
If such systems were used at all, it was mostly for very big systems, were a few percent of extra energy signifies some serious money and even offsets the salary of a maintenance guy.
I may be wrong, but I feel like the bigger the installation, the more the packing density outweighs the incidence angle optimization. The motion system is a fixed percentage cost/complexity adder, I guess, but if it doesn’t make sense for a two unit system, because of the lost space between the two, I can’t see that it’ll make sense for >2.
Exactly. I’ve recently been at a site that has 8m panels installed. Apart from the expense of a tracking system, there is just no space to allow for rotation of the panels. Elevation could still be an option, but given the harsh environment (desert sand, temps up to 122F/50C, etc) and the sheer scale, I suspect that any gains would be quickly outweighed by the additional maintenance required. Even if a failure occurs in 0.001% of the plant per year, that’s more than one per week that would need visiting. And there is literally no space between rows of panels to actually get a vehicle there.
You contradict yourself. First you say there is a difference for bigger installations, then you say it’s a fixed percentage.
A picture search gives an overview of what is out there:
https://duckduckgo.com/?hps=1&q=solar+tracker&iax=images&ia=images
I am a bit surprised that I see more dual axis systems then I expected, and also with bigger installations. There are also plenty of area’s where the size does not matter much. Think of putting solar panels in a desert.
I also like the idea of combining different functions, similar to a Eierlegende Wolmiglschsau :) In Germany whole pastures are planted full with solar panels occupying the land. But with a few solar installations on higher poles, the same area can still be used for grazing cows, and the panels provide shade for the cattle.
In area’s with lots of sun and little water, solar panels may help to give plants a chance to grow.
And of course rooftops. When solar panels get integrated into the rooftops of new houses, then they can act as the waterproofing layer (or reduce cost of the underlying (simpler) watertight layer to reduce the combined cost. (A solar tracker would not make any sense in this application).
https://de.wikipedia.org/wiki/Eierlegende_Wollmilchsau
There are always going to be trade offs, but solar tracking with current solar PV that is so very strongly angle of incidence dependent is going to net you on average a really vast amount power gained for the same sort of area covered, being both a more even output through the day and certain to be pointed at the sun in the weather windows.
So it really can be worth it as the maintenance costs will more than be made up for in extra power (assuming you have any use for more, won’t end up shading your own array etc). In our own setup here solar tracking really isn’t worth the expense or complexity, as it would almost certainly have meant more planning permissions to rebuild the roof structure to support it… But that does mean if the clouds insist on coming over in that two hour window either side optimal alignment the power output for that whole day on a good number of panels is pretty darn pathetic – the whole of that day will probably amount to less than just the one of those hours in sunshine…
Also if you don’t have solar tracking to even out the power generation you almost certainly want more energy storage, which adds its own complexity, maintenance and upfront cost… Really you have to view the whole system, or at least the whole of the node you are personally responsible for to make any sort of judgement on the best.
This is absolutely a ridiculous project, but it would be interesting and funny to make a multiaxis cnc controlled solar panel that could accommodate shadows by routing the panels around them. I’m imagining a couple scara arms waving panels around because there’s a church steeple shadow in the way for part of the day.
It is interesting not only because of solar performance, but also because of safety. A panel at a high angle is very vulnerable in strong winds. But with the help of this mechanism, it is possible to fold it to a horizontal position before or during strong winds.
That reminds me of the solar flower. Both a tracking system and “foldable”
https://duckduckgo.com/?hps=1&q=solar+flower&iax=images&ia=images
I guess this is also mostly used as an eye catcher. I never looked into the performance to cost ratio of this thing.
Hopefully it could stand vertical during hail storms….
But how to position it during hail storms with high wind?
I’m curious to know whether the energy increase you get from adjusting the tilt is more than the energy you spend running the motion control system.
Was curious about this too. It would be nice to use the system to measure the difference in energy output for the different off angles for different solar W/m2. But i’m guessing the gained performance compared to a static setup is not big enough for me to invest in such a system.
Energy collected with a panel on a dual axis tracking mount is 3 to 1. For an array, factor the extra space needed when tracking panels do not shadow each other. Even with the space added between them, the energy collected is higher than a densely packed non-tracking array. There are two major effects, the amount of sunlight intercepted by the panel, and the amount reflected due to the angle of the panel. For example, at 45 deg the shadow of the panel is reduced by 30% and the reflection off typical glass at that angle is about 30% for a total loss of 50%. That is only one interface layer.
I call total BS on the 3:1. Got a reference?
A fairly well-instrumented large (1 MW) non-tracked array on a school near me is measuring a capacity factor of 16%. This site is fairly cloudy, and there’s a planet that inconveniently gets in the way for half the time. There’s no way on god’s green earth you’ll ever get a capacity factor of 48% on a tracked array anywhere, let alone here.
1.3:1 is much more believable than 3:1
3:1 actually seems pretty conservative to me… Even the best solar panels are really very angle of incidence dependent and actually pointing at the sun 100% of the time it is over the horizon means that problem goes away – the only thing changing your power output then is the power of the sun reaching the panel. Which means you will get more even energy output through the day, and reliably get good good energy even on the more overcast days.
There are of course many variables, and your local weather is going to play a fairly major part – if you are prone to cloud cover the tracking system should get a much bigger gain over time compared to a fixed panel than in the most ideal location for solar generation imaginable.
No. 3:1 is completely ridiculous.
Multiple references show gains of 25-35% from tracking, compared to untracked.
One study claims 60% energy increase from a 2-axis tracker, which is the number you get from comparing the incident energy integral of an untracked surface to a tracked one, and does not account for the air mass loss due to looking through more atmosphere at low angles.
Even though there is an acceptance angle effect, surface treatment of modern solar panels mitigate that considerably.
A 3:1 (200% increase) is not a reasonable expectation.
Don’t believe me: go do the search yourself.
No Printed reference. Calculations and measurements made by me in the 1970’s for a company making a full tracking collector for hot water. And 3:1 is conservative since I only included one surface. There is an additional reflection for the other side of the glass and then any protective coating on the solar cells, etc. In my work it was a copper oxide that was a very good black.
Any good optics or E&M book will show have to find the power in the reflected and transmitted portions depending on angle and index of refraction (ratio of them). Google doesn’t produce anything but Snell’s law examples from descriptions in the search. You need the Fresnel Equations. https://en.wikipedia.org/wiki/Fresnel_equations
I have seen much smaller values published several times. I suspect they are wrong or are using some criteria that favors non-tracking systems. Likely they are just repeating a well published value of unknown source.
Ah, there’s your problem. An “incident energy integral” is just the projected area of the solar panel, or the sum of it’s shadow over time. Yes, you will get a number like that. How much energy reaches the silicon and can be converted to electric power? Include the reflections for panels with glass or Lexan as are used on homes and solar farms. I suppose I will have to start a Jupyter Lab notebook now……
Paul there are so many variables and it really depends on the timespan of the study – you pick a relatively short period tracking isn’t going to get as much gain, but once you start getting into serious seasonal differentials that fixed panel ends up in more trouble comparatively – its angle is now always very very wrong for months at a time with the sun never getting nearly as high (or much higher) in the sky. And the best moments of the day, which are just about the only ones a fixed panel really really works are more likely to be cloudy. Then the fact it is static means it is far more likely to catch and hold dirt and dust etc.
Now if your ‘fixed’ panel has a few adjustment stops through the seasons or live really near the equator, you keep it meticulously clean, never get real weather then the gap is going to close considerably. But in the real world based on the system we have here and its performance over the prolonged period that 3:1 actually seems quite conservative – it only takes an hour of overcast at the wrong time to tank a whole days average power production with a fixed panel, and playing with some light manual sun tracking on the smaller panel here at least you can get pretty darn close to the highest peak you could see even in the early morning/later evening by having the panel angled correctly – certainly massively massively closer than the fixed panel gets, which brings the average you’ll get through spotty cloud through a day up considerably.
You don’t need much energy to tilt even a relative big solar panel. Movement is slow, and it does not have to move much. If you want to push it, you can even mount the hinges near the center to balance the panel, and move it a bit every whole or half hour. The problem is more with all the costs for building the system and maintenance.
You don’t need much energy to move the panel, true, but that wasn’t my question.
Unless you’re pretty aggressive about minimizing quiescent draw, it’s easy to chew up all your gains.
That 400W panel would put out, on average, 80 watts. If the tilting gains you 5% (which is about what you’ll actually get, over just setting & forgetting), you only make an extra lousy 4 watts.
You better make sure your system burns (much) less than 4 watts on average, to make it worth it.
Or you take the $500 you spent on all that gear, and buy yourself another 400 watt panel instead, doubling your output, increasing reliability, and reducing your maintenance costs.
If the motor runs for 10s every hour, then your 4W average is 1440W during those 10 seconds, and that should be plenty. But indeed, buying an extra panel instead of the motor and moving mechanical construction makes more sense.
Also, adjusting the tilt as is done in the video is the easiest, but also least effective angle to change. When you rotate around the vertical axis, you can also get the morning and evening sun and that has much more effect. But even then, if you want a moderate amount of energy spread over the day, then mounting one panel to the south-east , and the other to the south-west has a similar effect without the mechanical complexity and maintenance.
You are better off cutting down the near by trees.
In Northern climates with snow, be it roof top or ground mounted, January and February can be sunny, but snow will cover any normal panel angle and at -20C will stay there for a week or more. Near vertical is required for at least as long as it takes to avoid snow accumulation and to shed it. As others have pointed out, going vertical to protect from hail or other weather events. Alas, it is mechanical, which introduces a major pain point. Think 25kW arrays and larger. Thinking bi-facial and various implementations of static positions that could be overbuilt for comparable results.
There is a solar farm in a shopping center near me. It has “industrial strength” trackers for its panels. The trackers were always breaking down. Eventually they gave up and just pointed them in one direction. This is the only tracking system I’ve seen in the area. Some people with roofs that slope east and west just put panels on both slopes.
I just drove by a large rural installation in New Mexico where, unusually, all the panels were on dual-tracking mounts.
I estimate that a quarter to a third of the mounts were completely screwed up, as those panels were facing in random directions.
So, kinda like the Palm Springs windmill farm, where a good fraction of the derelicts are plainly visible by passing traffic on I-10 ;-/
(Tour guide at solar farm)….”The rows of solar panels you see provide green power to the grid. Tracking motors keep the panels facing the sun resulting in a very efficient, eco friendly, and cost effective way to generate power.”
(Visitor) …. “So why is there a long cord from them plugged into an outlet ?”
(Tour guide)….”Well, how else are we going to run the tracking motors ?” 😁
Hack an old Starlink terminal (which has multiaxis tilting) to follow the Sun instead of a Starlink satellite.
If you can mount a 100w panel on this Starlink mechanism, you might generate enough power to operate a separate actual Starlink terminal.
I’ve suggested this to Starlink themselves, but no response so far.
The tilt angle is the least important to adjust, adjust it in 3 steps, summer, fall/spring and winter, that is enough, while tracking over the day is important every day, every season.
I have a drawing for a roofrack for a campervan with just that, 3 steps tiltup (and flat for driving) and horizontal tracking during the day.
First iteration only had a timer that moved the panel (the suns movement is pretty time-predictable) the other iteration had photodiodes or small solarpanels angled from each other to compare the best angle.
There is also an old suntracker that uses a hydralic cylinder filled with wax that uses termal expansion of the wax in the more sunlit side to adjust for equal shade/temperature on both ends of the cylinder if you are solder-allergic and wants an non electronic solution.
The easy to remember number for Earth rotations “A degree every 4 minutes”.
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