I used to be like OP. (have a similar background and have similar interests in tech for the planet)
Then I realised couple of things, an humbling experience:
1) given any position on earth, you can compute exactly what's the optimal inclination at any given point in time for a PV to maximize the energy production. Sure, there are reflection and secondary irradiation conditions (eg.: there is a lake close to it), but again, assuming the environment is static, it's way faster to just compute it statically rather than dynamically. Also, in most scenarios Beam irradiance from diffusion (the beam hitting the object) is order of magnitude higher than from reflective one (the same beam bouncing on a 3rd object first).
2) In mechanics movable part are the things to avoid. They have lower MTBF (mean time before failure) and as such they introduce complexity and increase cost
3) Economics is a key component of engineering. There is a cost to everything, the computational power, the energy needed by the servo, etc, etc. Given 1 and 2, a dynamic solution simply has a lower ROI than a static one.
I really appreciate the OP exploration here: there is a good overview of basic control theory and a good foundation of ML (although don't be deceived, this is a very simple modelling task that OP is overkilling with a way more complex model). That said, for everyone reading, this is not something you want to do in a real world situation.
On a large scale motorized sun tracking photovoltaics is very costly. The systems that can take the wind loading of six 1.65 x 1.00 meter size 60-cell panels on a pole cost more than the panels. Needs like a 6" OD sch80 pipe set into a concrete foundation.
Commodity fixed angle ground mount photovoltaics arrays are low cost.
If you do the dollar and kWh produced in year calculation for spending $40,000 on fixed mount ground pv, and $40k on a combination of pv panels on trackers, and compare the kWh proxied by both... The fixed ground mount comes out far ahead.
A tracking mount can make sense only if you have a VERY small amount of space to work with and want the absolute most kWh per month per square meter of area occupied on the ground. And don't care about money much.
Heliostat installations used to be common when panels were so expensive that spacing them out wide enough to keep them from shadowing each other when angled for dusk/dawn made sense. Now heliostats are only done in exceptional situations, for example I've seen some that didn't seem to be particularly old on rugged terrain were the quantity approach would be costly as well and easy foundation opportunities are sufficiently far from each other to prevent peer shadowing anyways.
But I do wonder if heliostats might see quite a revival in agrovoltaics: there, you want a certain distance between panels anyways, and perhaps the plants won't mind if you steal a little more light off-noon in exchange for less shadowing at noon. Electricity supply/demand would certainly applaud this bias, in a market with lots of photovoltaics a Wh at noon is certainly worth less than those closer the the periphery of the daily sun cycle.
And if you do agrovoltaics right, the structure will be expensive anyways (making the markup for heliostat insignificant) because imho it's still just an unfinished prototype if the structures for holding the panels aren't designed to double as an overhead rail system for farming powertools that could become a considerable efficiency gain over the century-old game of tractor vs mud.
Yeah, exactly. Tracking photovoltaics used to be worth it back when photovoltaics were $5 per watt. The price has dropped so much that even for fixed angle ground mounts, the mounting frames and labour to install them costs far more than the panels themselves. Sun-tracking is just not economical compared with cheap static panels.
(I spent quite a lot of time on an idea for rooftop solar thermal power and was trying to build a prototype when the solar panel prices started crashing. It pretty soon became inescapable fact that small scale solar thermal with all its moving parts just wasn't viable any more. I'd be surprised if even the large mirror-farm CSP is competitive these days.)
Thermal for heating/hot shower or thermal for some adventure in driving a generator?
For heating, photovoltaics supplying a heat pump is starting to give direct thermal a run for the money (well, not actually for the money yet, direct thermal is still cheaper, but at least in terms of how much you could harvest from a given roof area)
If money isn't an objection at all, e.g. if you strive for that sense of achievement of a good setup, there are hybrid modules that pick up the 20% or so photovoltaics achieves and still funnel the remaining energy into heating a liquid medium.
This idea was a flat "panel" of parabolic reflectors focused on heat exchanger tubes, driving a heat engine. The new bit was that the heat engine was going to be open loop (basically Brayton cycle with the compression stroke pushing air into the heat exchanger and expansion stroke driven by heated air from the exchanger) so its power density would have been much higher and cost lower than the usual Stirling cycle engines which cost a ridiculous amount for what they are.
I had all the thermodynamics worked out and it would have been something like 5x as cost effective as photovoltaic. Then the cost of photovoltaic panels dropped 10x in a year. C'est la vie, at least my roof is covered in PV now. I've thought of running some tubing under the panels to pre-heat water for our solar hot water system but these days it's scarcely worth the bother (at least where I live which is pretty much perfect for solar power.)
There are hybrid solution of panels that are basically layering a PV over a Thermal Panel (pipes with fluid inside). I never saw them getting massive traction. I wondered why.
Reminds me of a bug in a certain laptop docking firmware that considers TjMax of 95F (instead of 95C) and running the CPU at full throttle mode (like 400MHz) at all times.
I went on a solar power course at the Centre for Alternative Technology in Wales (~10 years ago, so perhaps this into may be somewhat out of date) and they'd calculated that the extra energy generated by moving a panel to the optimal direction during the day was less than the energy it took to move the panel, let along the extra costs of the mechanics. Bear in mind that in Wales there's plenty of cloudy weather during the year, so light is often diffuse, and it's quite a long way north (the gulf stream tricks people into thinking the UK is further south than it is, but the CfAT is 600 miles further north than Toronto). If you're somewhere with lots of direct sunlight that calculation might be different, but as others have pointed out, that doesn't take into account the cost of the mechanics and controllers.
Can you make a purely mechanical solution to the tracking problem, at least along a single axis? If you put a water container on the left and the right side of the solar panels, the one in the sun will get hotter, expand, and that can move the solar panel. It's moving parts and extra cost, but no energy consumption.
I'm no engineer, so I can't determine whether it would work, but on the surface it looks like it should?
I remember a guy in a community that I frequent that build a small trailer that had fixed solar panels, he had build one for a reason I don't remember and afterward some companies were interested and that post was showing his second one he had just sold. It was a bunch of panels on an A frame so essentially one side had awful sun visibility but not the other. People wondered why he did it in such ways, as that meant that half the time they would be useless, why not a moving platform on a central pivot that you can adjust? Well turns out it was cheaper to add panels on the other sides than building a more complex frame that allowed pivot. I'm sure it could have been cheaper to build a system sure (maybe not in his case considering it was on a trailer), but I have an hard time believing the maintenance cost and failure potential is worth it. You can just add more panels... they are starting to become that cheap.
I can imagine that this kind of research is done once 15 years ago, as I remember that too, but perhaps with the recent advance of technology might actually not be true anymore. I don’t have sources but in general some types of things get reiterated so long that time overtook it
As GP argued, the movement can be entirely precomputed, and even if it isn't "move the panel to face the brightest spot" is trivial to solve with simple components. The only real advances I can imagine to make this profitable would be better motors that are cheaper and use less energy, or new types of solar panels that are more directional (e.g. a solar concentrator setup where you move mirrors to hit a smaller collector).
The latter exist but don't seem more profitable (in the case of PV panels because of lifetime problems due to more heat), and while we have gotten a bit better with motors I don't think there even is a lot of headroom to gain much efficiency.
Y'all have plenty of water in Wales: it feels like a simple water clock could do a trivial repositioning of the panels to do precomputed solar tracking.
> 3) Economics is a key component of engineering. There is a cost to everything, the computational power, the energy needed by the servo, etc, etc. Given 1 and 2, a dynamic solution simply has a lower ROI than a static one.
A 'joke' we had in engineering school: Anyone can design something to do X for $5, but it's an engineer's job to get the same results for $3.
Yes, I agree this is vastly over-engineered. There are commercial solar farms that actively point toward the sun, but many (most?) do not, because they may fail. Before medicine, I studied and worked in renewable energy: in medicine, simplicity in critical engineering problems is more obviously important.
In this solar project, the metric should be a comparison to the yield from pointing at the sun based on lat,long, and (earth) time.
Really, the analysis would have to include anticipated costs of installation and maintenance in comparison to a dumb array.
Perhaps the ingenious author could consider xy or xyz movement in an intermittently shadowed environment instead of 2-axis rotation. This might be be a better job for machine learning, or just a well-known control system problem.
Then I realised couple of things, an humbling experience:
1) given any position on earth, you can compute exactly what's the optimal inclination at any given point in time for a PV to maximize the energy production. Sure, there are reflection and secondary irradiation conditions (eg.: there is a lake close to it), but again, assuming the environment is static, it's way faster to just compute it statically rather than dynamically. Also, in most scenarios Beam irradiance from diffusion (the beam hitting the object) is order of magnitude higher than from reflective one (the same beam bouncing on a 3rd object first).
2) In mechanics movable part are the things to avoid. They have lower MTBF (mean time before failure) and as such they introduce complexity and increase cost
3) Economics is a key component of engineering. There is a cost to everything, the computational power, the energy needed by the servo, etc, etc. Given 1 and 2, a dynamic solution simply has a lower ROI than a static one.
I really appreciate the OP exploration here: there is a good overview of basic control theory and a good foundation of ML (although don't be deceived, this is a very simple modelling task that OP is overkilling with a way more complex model). That said, for everyone reading, this is not something you want to do in a real world situation.