If you want solar power, you usually have to make a choice. You can put a solar panel in a fixed location and accept that it will only put out the maximum when the sun is properly positioned. Or, you can make the panels move to track the sun.
While this isn’t difficult, it does add cost and complexity, plus mechanical systems usually need more maintenance. According to [Xavier Derdenback], now that solar panels are cheaper than ever, it is a waste of money to make a tracking array. Instead, you can build a system that looks to the east and the west. The math says it is more cost effective.
The idea is simple. If you have panels facing each direction, then one side will do better than the other side in the morning. The post points out that a tracking setup, of course, will produce more power. That’s not the argument. However, for a given power output, the east-west solution has lower installation costs and uses less land.
Letting the post speak for itself:
East-West arrays are simple. They consist of parallel strings of PV modules that are oriented in opposing directions, one facing East and the other West. The current of the whole array is the summation of these string currents, effectively letting East-West arrays capture sunlight from dawn till dusk, similar to a tracked array.
So what do you think? Are solar trackers old hat? If you want one, they don’t have to be very complex. But still easier to just double your panels.
Tracking systems for solar panels have always been a very niche phenomena because of this. Even 20 years ago when solar panels were still expensive, tracking systems were rare. And it’s not only installation cost, and (regular) maintenance. It’s also the bulk of a moving system that is impractical in a lot of situations. The only large scale application of solar trackers is with systems that concentrate solar energy before conversion.
Pointing solar panels southward (in the northern hemisphere) has been common, but I guess that east / west orientations (or south-east / south-west) is becoming more common in the long term. Here in the EU (and I heard also Australia) the amount you get for generating solar power is becoming variable, with at some moments even negative prices. and those moments are of course during peak delivery. With more East / West pointing panels, generation of solar energy would be more spread over the day.
One thing I’ve find both flabbergasting and annoying is the existence of “solar farms”, where precious land area is used for nothing else but solar panels. I’d say ground is too precious to waste it for such applications. Putting these things on roofs is a good place for them. Making the whole roof out of solar panels (for new houses) would be even better. Putting a few of them in pastures apparently also make sense as it provides a shady area for the grazing animals, but I never looked into further details.
I recently watched a youtube video about using bifacial solar panels vertically mounted in an east/west orientation. The results were pretty positive. However, a very simple tracking system might make this much better. If the panel had a mounting with three, fixed positions: inclined to the east in the morning, horizontal around midday, and incline to the west in the afternoon/evening. The change of position could be done with a timer. The logic and electronics to adjust the time according to the season should be pretty simple. I leave it to the more mechanically aware to say if this might work. A simple flip for east inclination to west would be simpler and, maybe, near as efficient. No timer necessary, just flip at midday.
video: https://www.youtube.com/watch?v=LqizLQDi9BM
“Precious land area”? There’s an entire planet’s worth of land. And the bits that get the most sun tend to be the least used.
We want the power where the land is used and people are… Ideally on structures that already exist, rather than squatting on land that could be used for other things.
There are a lot of applications for power where there are no people.
Such as carbon sequestration. The company “Verdox” (not an advertisement) has figured out an electrochemical way to extract CO2 from the atmosphere, and we could pump liquid CO2 back into the ground where it would be converted into carbonates.
Such as fuel production. Slowly make fossil fuels and store it locally, send a tanker out once a month to gather the proceeds.
Such as ammonia production. Currently this uses 5% of the world’s energy production (for fertilizer), slowly make ammonia and send a tanker out once a month to gather the proceeds.
And I read just last week that some Chinese researchers created robots that can install solar panels. Without human labor. (I assume this is “mostly” without human labor.)
The idea of building a factory in the middle of nowhere to gather solar power, and then using that power to install more panels, and then using the excess power to do something valuable…
is no longer science fiction.
My understanding of CO2 is that it can only be liquid under high pressure. Pumping it into the ground and expecting it to remain a liquid until it reacts chemically seems unlikely.
“Pumping it into the ground and expecting it to remain a liquid until it reacts chemically seems unlikely.”
You don’t expect it to remain a liquid.
@chris maple
You realize that things underground ARE at higher pressure right. Right?
Here in the Netherlands, we have 520 people per square km and there really is not much empty space.
Sure, plenty of empty deserts. Mostly empty. There have been several plans for big solar installations in the northern Sahara, but due to political instability in the area, no one is willing to build such an installation over there, and I can’t blame them.
Saudi Arabia and thereabouts are some pretty big solar installations, even though oil is (still) cheap there.
It is possible to build some HVDC lines from the Sahara to the EU. There already are some pretty long HVDC lines. It would be curious whether https://en.wikipedia.org/wiki/Australia-Asia_Power_Link would ever get built…
I also just bumped into the proposed:
https://en.wikipedia.org/wiki/Xlinks_Morocco%E2%80%93UK_Power_Project
But for small installations, I agree with Hacaday article that it’s (probably) not cost effective to build moving installations for solar.
I read an article (https://solarmagazine.nl/nieuws-zonne-energie/i40452/daken-niet-vol-alle-stroom-die-we-met-zonnepanelen-kunnen-oogsten-moeten-we-oogsten) that states that in the Netherlands about 20% of household roof surface has solar panels. Not all that 80% remaining roof is technically or economically possible, e.g. north-facing, shadowed roofs, roofs that are not strong enough or that aren’t allowed to have solar panels (i.e. directly under a runway), and some homeowners just haven’t cared enough.
In my appartment building, the roof is in a legal limbo, it is co-owned by both the HOA ánd the people on the upper floor (who are allowed by the HOA to install a roof terrace, just not by the municipality) and constructing solar panels will infringe on those owners’ property rights. We have not been able to find a legal advisor that was able to find a legally stable way out of that.
For larger roofs on warehouses etc, I once read (can’t find the link) that close to the full economic percentage is leveraged, as there are a lot of roofs that are built too light to bear the extra weight of solar panels, and insurers sometimes forbid it due to fire risk.
‘Straya has loads of ‘waste’ land with AAA solarization. The issue is distance, and a lack of power transmission infrastructure. Once we ring the planet with superconductive power transmission lines, then the storage problem also goes away. I’m just musing.
They’re already out of land in Europe tho, and have resorted to putting panels out at sea
There are solar farms where the solar panels are more elevated and spaced than usual, and the shaded ground under them is used to grow strawberries. Any other culture that need partial shade can thrive under solar panels
The least used is also often the least populated and the furthest from cities, so transport/conversion losses and infrastructure costs become prevalent.
I pointed my small setup (4 panels) West due to trees on the next property that didn’t give me due south sky access. When I added another 10 there were angled to face Southwest.
You will need another microinverter, so that’s added to the panel cost.
I dont mind ground mount solar farms that much, but we really do need to get more panels on the roofs of homes. My 10-panel setup supplies me 4kw, which is not a huge amount, its over 50% of my energy use in the spring & fall. On the other hand, with my reports receive, I can tell you which days we had rain!
Here are some photos in this Quora answer: https://www.quora.com/Today-is-Earth-Day-How-are-you-contributing/answer/Steve-Heckman-1
I’m a fan of covering parking lots. In the US the parking lots for retail stores in suburban areas is easily twice the square feet of the stores they serve. Both the tarmac and the vehicles generate heat. We are not going to give up our individual vehicles or big box stores any time soon, so lets cover that mostly unused space with panels to provide shade for the surface and vehicles while generating energy to run the businesses.
https://maps.app.goo.gl/b8xcScnVF5f2ts4MA
https://maps.app.goo.gl/xZVoVKvpZsRfRtoz8
We could generate enough solar power to replace the US’s energy use just replacing the space we use to grow corn for ethanol (about 27 million acres.) Taking a national average of about 5.5 sun hours, and a utilization rate of about 1MW per 10 acres, that’s 2.7TW of solar. 5420.25 TWH per year, or about 20% of the US’s total ENERGY use.
Solar power is certainly variable especially in the north europe, plenty of sun during summer, no sun during winter.
There’s power per panel and power per land area.
A single-axis tracking row of panels does not need more space than the panels laid flat on the ground, bar a pivot at either ends in the simplest design, but produces something like 25% more power than a fixed array.
A fixed east/west array collects the exact same amount of energy as a fixed east or fixed west array with the same number of panels – varied orientation just distributes the power output over the day.
As such, the east/west array will need to pack 20% tighter than the single axis tracker to have the same power output with the same land and even tighter to do so with less land.
They will pack tightly at very steep angles, but it seems like using them near flat was part of the pitch for its simplicity.
Considering that any east/west panel configuration could also be made to increase the angle for tracking (e.g., by lifting the top or lowering the bottom, creating gaps), which while less efficient than proper tracking uses no more space than the east/west configuration that was modified, it seems impossible for east/west to be more land effective than a compact tracker.
Might still be cheaper in some places of course. Although, a fixed panel oriented something other than due east or due west might be much more appropriate at some latitudes and intended load patterns, please check with a solar calculator.
There is only so much solar irradiance on a given area, if you cover the land 100% with flat laying panels, you get all the energy you can get. By tilting the panels you cast a shadow, from which the next row must stay clear. So (static or dynamic) tilting only increases the output, if you can’t place the panels next to each other in the first place.
It will of course depend on the location, but here in the Netherlands you hardly see tracking systems. A lot of the energy is generated during cloudy days. This reduces much the effect of the theorethical cosine theta reduction. Purely from an irradiation perspective, you loose only about 10 % when laying them flat, compared to oriented at peak angle. You of course would loose self-cleaning. See for example the following graph for angle dependancy. https://voltasolar.nl/wp-content/uploads/opbrengst-instralingsschijf-zonnepanelen.webp
Sorry, I need to correct myself a little. The graph is comparing orientation of fixed positions, it is not comparing to a tracking system. On a quick search I found roughly 20% gain from a tracker compared to a fixed system in the UK, which is at roughly the same latitude an probably has similar cloud coverage. Given the price of a tracker, you better place 20% more panels.
Or they can all be optimized for power output during peak solar exposure and the power stored in batteries so it can be slowly discharged as the sun sets.
As soon as someone adds smallish batteries to mount in tandem with micro-inverters , between the solar panel and micro-inverter, the problem is solved for many. Will cost a little more but the system automatically scales with each added solar panel, micro-inverter, battery module.
I was going to do that but opted to invest $20k and just install a 12kW hybrid inverter and 50kWh of LFP batteries to go with the 7.5kW of solar panels(2 strings, 1 optimized for winter elevation). No grid used since Nov 2024 and now we charge not only our two EVs but also 2 of the neighbors EVs.
Charging four EVs on that? Impressive. It implies you don’t drive a whole lot: The amount of energy you get from that array would make maybe 15 miles/day for each. (though I’ll admit “a whole lot” depends on where you live — our family car sees half that usage, so an EV is pointless for us.)
People ask whether it would be effective to install solar panels on the roof of an EV.
Tesla pointed out that if the car was in direct sunlight all day it would add the equivalent of 20 miles to the range each day.
A 7.5 kW array at 550 watts is about 14 panels, or 280 added miles divided by 4 EVs is about 70 miles added each day.
That’s not bad as a daily addition. I frequently drive more than 70 miles, but not every single day.
I’m not following that arithmetic.
Tesla’s numbers are in ‘spherical cow’ territory.
7.5 kWpeak at a 16% capacity factor (the going average here around the 43rd parallel), is 1.2 kW, 29 kWh/d, or 7.2 kWh per car. After panel-inverter-storage-inverter-distribution-charger-storage-standby (i.e., real) losses, that’s around 15 miles range.
yeah that’s something that always stands out about cars…every car has a different portion of long trips vs short trips and busy days vs idle days. at the extremes, they look like totally different problem spaces. you see someone at the other extreme and naturally say “that’s hardly a car at all”
“with the 7.5kW of solar panels(2 strings, 1 optimized for winter elevation).”
Okay, obviously manual solar tracking east/west isn’t possible, but I don’t get why you wouldn’t make a setup whose elevation can be altered during the year. I mean, it’s not like twice-yearly maintenance is a huge deal.
Solar trackers do not need to be full pan-tilt affairs. A single tilt point allowing the panels to move east to west, a small DC geared motor, and a couple small side panels to drive the motor. Done.
This does full pan-tilt, but could be simplified even further:
https://www.youtube.com/watch?v=wL9PcGu_xrA
From my experience, the discussion of if you should fit solar is over, it works and works so much better that you would expect. As this article points out, when you fit it put as many panels up as you can. They call it ‘over panelling’. The panels are the cheapest part of the system.
I have a modest system, 12 panels 6 on each side of the roof. Both are not in the ideal direction which is why I fitted as much as I could. 5.2kWh of solar. This time of year I see peek 3.2kWh which blew my mind. Over the year I use 2500 kWh and generate 2000 kWh. I have a 12kHw battery and inverter outputs max 6kWh. I have no gas, all electric. Energy bill down from £2000 a year too £700. Also, if you can, get the ‘island mode’ fitted. No more power cuts for me.
Can someone explain why they don’t just place the solar panels flat? When the east panel gets more power the west one gets less so it’s just a zero sum, isn’t it? Does it make a difference if we get out 200W/SQM (from the perspective of the sun) if it’s on one solar panel or spread out to three solar panels because they are at an angle relative to the sun?
i think generally the panels are flat in practice…just tilted north-south for your latitude. but if you can fit more panels by orienting them in different directions then that will be a win in capacity. the idea is to take the money you might spend on a motor / moving mount and spend that instead on more panels. it’s the greater number of panels not necessarily the directions they face
Tilting the panels produces more power per day and spreads it more evenly across the day. If your battery charger or inverter can’t handle the noon production, it is wasted.
Tracking rigs are basically like steerable dish antennas, not very practical. Also there are the seasons to worry about so your solution must to account for them as well. 9 times out of 10 is better to just overbuild and install more panels obviously if you can afford it. The last rig I worked with gave us a very consistente output all year long, moreso having 300+ days of sun.
‘old hat’ ? quite the opposite. Until we massively break the economy to the point where we cant get them at a reasonable price motors, metal, and controllers are cheap. Especially compared to the cost of power conditioning, sotrage, and conditioning that also get put in place.
Also solar tracking doesn’t take more land in most setup. Not like you can put the next solar panel in the shadow of the 1st anyway. This is just someone trying to argue for simple. Simple does have a benefit but that commentary is overstating it and trying too hard.
Shouldn’t that depend on application? If you need more power but have less space you track sun, otherwise you go with fixed installation?
I have a small book with a schematic for a simple tracking system without any extra electronica. It has 2 small identical vertivke solar panels sideways on the horizontal direction, both connected to the motor that turns the solar panel. If one of these solar panels gets more sun, it automaticly runs the motor, and in that way the panel is always horizontally pointed toward the sun.
I bet you could also place 2 horizontal panels to put the vertical direction towards the sun too ;)
The real problem is: storm. There are no easy solutions for directional systems when it comes ti surviving a storm.
And nothing beats heat pipes, which get 60% efficiency (instead of 20% for solar) without moving parts!
I have solar PV and thermal, but I am no fool and know that there are natural events that can render them useless for long periods of time so I have looked into back ups and optimisation options. Solar thermal will still operate in conditions where PV is effectively useless. As for tracking, the right sort of lenticular array over the cells may improve early and late in the day output levels.
“Tracking rigs are basically like steerable dish antennas”
There should be a law that says you can’t build a solar “tracking rig” until you’ve talked to an astronomer first.
To track the sun all you need is rotation on a single axis, and the control is no more complex than a clock. The tilt of that axis is the important bit – it needs to parallel the axis of the earth’s rotation.
It’s called an equatorial mount.
“To track the sun all you need is rotation on a single axis,”
uh… no
To track the sun over the period of one day, you need a single axis.
To track the sun over the period of one year, you need two.
In a world where we are talking about mounting solar panels facing east and west, tracking the sun on single equatorial axis should be “good enough”.
Using bifacial panels is far more cost effective. Current mainstream TOPCON panels have a bifaciality of 80%, and have no material difference in price compared to monofacial panels.
I see two solvable problems with bifacial PV. The first is the lack of good simulation software with local weather data. For places that usually get snow in the winter, the increase in albedo is large compared to grass or even crushed rock.
The second problem is mounting systems. I’m experimenting with vertical bifacial PV, and have had to build the mounting systems myself. For fixed-tilt, I can choose from multiple mounting systems such as Clenergy, Fastrack, and Polar Racking.