Article doesn't give a whole lot of context, but there's two key innovations here:
1. Bi-facial solar panels: can take in sunlight from either end
2. Mounting bi-facials vertically so they can take in sunlight from both directions.
I've been hearing experiments about these for a few years now. There's three main benefits to the vertical arrangement that could, given certain situations, make it more economically valuable:
1. In places with high-albedo snowy winters, this arrangement can boost winter production, which if you have snow, tends to be the energy-heavy time of year.
2. Keeps panels cooler. Panels lose efficiency when they get hot, and by having them vertical, they can run cooler. Losses in less direct sunlight are somewhat offset by efficiency gains from cooler operations.
3. More power during shoulder periods (anti-duck-curve). Especially in places like California that have high solar penetration, prices for excess energy are minimal during peak solar activity. Vertical arrangements give more power in the morning and evening, which is when traditional fields are just ramping up or ramping down. Thus, even if you're making less power overall, you can be making more valuable power by having more production during these ramp-up/ramp-down periods.
Unclear how much of an effect these counter-acting forces actually add, but I understand solar developers are looking into these arrangements.
I strongly recommend watching Dave’s entire video, it’s really extensive and interesting.
Notably while the N/S bifacial have an amazing showing in sunny winter day with ground snow (as well a significantly higher resilience against snowfalls), the year round testing he did shows that the performance crater in spring, with half the performance of standard inclined panels, and none of the morning / evening advantages of E/W bifacials.
In the end, the N/S verticals have a worse year round production than every other setup, and significantly worse than standard, but if you live in a location with a fair amount of winter snow and can swing (heh) it a tilting mount could be an interesting configuration for winter.
What if we do vertical bi-facial panels, mounted on a rotating circle that rotates to align the panels with the sun (north-south or east-east or in between) depending on the time of the year. Wouldn't that be the best of all worlds right now?
The anti-duck-curve is actually really, really pronounced for east-west mounted bifacial panels.
The panels still don't generate any electricity at night of course, but other than that the output is an almost perfect inverse of the conventional equator-facing angled mounted panel output.
My next array is likely to be east-west vertical bifacials, as I need only a small amount of additional capacity in the summer, but could still do more in the winter.
We currently have:
- summer optimised array: almost flat, 15 degree, optimised for maximum power on sunny summer days, mostly runs our cooling
- winter/morning array. Points SSE, 65 degree incline. Gets great energy in the mornings, and on winter mornings. Performs surprisingly well in overcast conditions. Generates about the same power in midwinter and midsummer.
- winter/afternoon array. Same as the above, but SSW.
18kW total faceplate capacity, in reality we peak at around 5kW, but have that for about six hours of the day for 9 months of the year. Also means I can run three arrays on two MPPTs as the two tilted arrays are basically mutually exclusive as to when they make power.
The other reason for leaning towards vertical panels is cleaning. The flat panels accumulate a crust of crap (pollen, soot, dust) that cements on there fast, and requires vigorous scrubbing to remove. Kills 20% of the capacity unless I get up there with a broom every six weeks. The 65 degree ones I have not had to clean once, as stuff just slides off them.
That, and a pallet of bifacials is now cheaper than a pallet of monofacials.
Not having snow accumulate on the panels definitely will be contributing to that gain since a bunch is lost on more horizontal panels in those parts of the world due to a layer of snow sitting on top for quite some time after the event.
One big trade off/risk is a large vertical panel essentially becomes a sail in high winds.
4. they can be setup in places where flat-mounted panels are not an option, like agriculturally used fields. Veritcal pannels allow livestock and/or food production on those areas, while preserving access for tractors and machinery.
A vertical panel has infinite higher efficiency that a flat-mounted one, if a flat-mounted one couldn't be constructed due to floor requirements.
this is an instantiation of my favorite problem-solving maxim that I learned in spirit as a boy scout: "Doing something suboptimal is almost always better than not doing something optimal." When my scoutmaster said it it had a few more four letter words and smelled like cherry brandy, but it was still true.
Only at lower latitudes. In the high north, the better config is vertical but one-sided in a V pointing south. Ideally then, one panel is face-on during the long sunrise, the other during the long sunset. Compare to at the equator where one side of a two-sided panel is facing the sunset/rise.
This opens the interesting prospect of hinged vertical pannels that could be adjusted for the season, opening up the V in winter and closing it in summer
If you have a south (or SE or SW) facing wall without much shadowing from nearby buildings or trees, vertikal mounting does work OK. Do not expect to reach the panel's nominal Wp rating though, output will peak at 50-70% of that. But panels are cheap - if there's enough room, just overprovision twofold. Just take care to buy an inverter that is OK with such a bigger configuration.
And vertically mounted panels will generate more power off-season than tilted ones.
Think of them as (glass) fence panels with a convenient mounting frame.
Just respect their dislike for partial shading from objects that are "near" (cast a hard shadow with wel defined borders relative to the cell/grid size on the panel), and it'll be fine.
If they are arranged to have substantially different sun intensity and/or timing, run them through separate MPPTs or use "power optimizers" that do the same effort but without requiring more wires back to central than the simple "one single string of panels" has.
Due to recent issues out there: calculate worst winter peak voltage and make sure there's a healthy margin to the peak allowed safe/no-damage input voltage to the MPPT/charge-controller/inverter.
Panels eat less of their own current at any given operating voltage, the colder they are. And winter mornings after soaking in night cold are worst case conditions for that as they had no time to heat up yet for the first minutes past sunrise.
> 1. In places with high-albedo snowy winters, this arrangement can boost winter production, which if you have snow, tends to be the energy-heavy time of year.
I guess you also don't need to remove the snow from the panels?
A comment that I heard recently is that in some places using solar panels is literally cheaper than using wood panels for fences.
I'm not sure how true that is of course but it does make you think a bit. The optimal place where to put solar panels increasingly is becoming "wherever you can afford to". If vertical space is what you have, why not use it?
People in apartments don't have access to roofs. But they might have balconies. Balcony railings can fit a few solar panels usually.
You can buy solar panels for use on balconies in the supermarket in Germany. They only generate a few hundred watt. But that can add up to close to something like a kwh per day if you get a lot of sun on your balcony. At 40 cents per kwh. That's 12 or so euros per month. I pay about 70 per month currently. And I can get a couple of balcony panels for something like 200-300 euros. And I might get some money back on those even. The idea with balcony solar is that it might offset part of what your fridge uses. You simply plug it into a wall socket and your fridge takes that power instead of from the grid. All safe and approved equipment, the inverter cuts the power if there is no grid power.
I haven't done this (my balcony faces east and only gets a few hours of sun in the early morning). But it's easy to see how this could work.
Quick look near here -- wood panels are ~50-99eur for .9->1.8m x 1.8m fence panels. I've priced out 550W solar panels (which should be about 1x2M) for about 100£. (Both retail, but different countries (ire/uk))
So, not price parity but also only about a factor of 2 or so. On the other hand, Ali Express panels are about half that UK price at a 10 panel quantity, with unknown shipping.
I'm kind of eyeing the concrete block wall in the back garden currently covered by a hedge.
It's just a matter of buying the right equipment. If you buy the wrong inverter, it just switches off when the grid goes out. You need some device that detects that and can disconnect from the grid (to prevent power going out to the grid) and then power the house. This is called islanding. Not all inverters support this. The ones that don't will switch off when the grid goes out. In addition to that, you might need a physical switch or transferring device that takes care of making sure no power leaks to the grid in case of an outage. Setups without this require inverters with anti-islanding that will switch off if the grid power drops.
Outages are rare enough here in Germany that few people go the extra effort and cost to install the necessary equipment. But with the right equipment (which is available if you go look for it), you can definitely get this installed. In places like Australia, outages are more common and it's generally not that costly to upgrade your setup to support proper islanding and it's more common for people to design their systems for this.
Of course people if feel compelled to prepare for WW III that might be a good motivation. On the other hand, we'll have bigger issues if it comes to that.
Almost no private solar installations give power during outage, for the most part they use something called a grid tied inverter. This uses the power grid to shape the waveform and costs about a tenth of what a self shaping inverter costs. the unexpected downside, no grid, no power.
I have yet to find conclusive evidence if it is possible to use a small full inverter to drive grid tied inverters, that is, have the grid off capability of a full inverter with the cheap cost of a grid tied inverter. It sounds reasonable, but I don't see anyone doing it.
>A comment that I heard recently is that in some places using solar panels is literally cheaper than using wood panels for fences.
...that might have been my comment. Or someone else repeating it. I was wrong, I misremembered "in X years solar is projected to be cheaper than wood panels for fences". X being, IIRC, maybe 3 years?
The point still stands, but the fact doesn't. Not til ~2028.
At 45°N latitude, I keep mine nearly vertical year round. I used to adjust them 4 times a year for more optimal production. There are issues beyond angle of incidence. Being nearly vertical keeps the snow off in the winter. In the summer it reduces the cleaning required (it's a sea bird rookery, so that's kind of a lot). Beyond that, the telemetry needs are constant year round so if the panels can cover the needs in the winter, then summer is no problem.
My current strategy for small installations when you have an equator facing wall or fence is slap the panels on it and be done with it.
In addition to bi-facials starting to work quite well, HNers may be interested in a rising class of ultra-low-mass material that has come out of work at Stanford and Intel in transition-metal dichalcogenides (TMDs) (e.g. for MoS₂, WS₂, WSe₂, etc.).
It turns out these enable a very high specific-power PV cell that adds another even more attractive production curve behind what is happening in vertical bi-facials. See e.g.:
It's such an interesting optimization problem. Maximizing annual production isn't the only goal. It's also about: never running out of power, having surplus power when useful, minimizing installation cost, minimizing maintenance cost, guarding against dust and hail, minimizing use of land, etc.
The cost is now at the point where we don't care so much about actually using every watt and when we do need more watts at a particular time we add more in "inefficient" configurations to supply it.
Whole industries are going to pop up to take advantage of the intermittent very cheap electricity. Also there will be a competitive balance between the cost of storage and the "cost" of non-optimally aligned solar panels.
Labor costs remain the limiting factor for me. The numbers only work out well if I DIY most of the work, despite being in one of the two or three most expensive electricity markets in the US. Like, the panels could be free and it'd barely change this, the labor's so expensive.
The other discouraging part is that as I understand it it's tricky to build the systems out a little at a time, e.g. start with five panels and no battery, add another five panels and batteries to the mix a few months later, add another ten panels another year later, stuff like that, without ending up with a lot of duplicated equipment and kind of a mess of an installation.
So far we dont have any industries popping up, other than battery storage. Intermittent power means unused capex some of the time which means the thing needs to be cheap. Is there a category that fits?
Earth mounting reminds me of when I used to daydream about autonomous, mobile, solar panel factories to cover huge swathes of sandy desert with solar panels. I doubt the mobile factory thing would ever make sense, but autonomous installation would be really cool.
Am I reading this correctly? Vertically they produce 77% compared to 90% of the tilted panels? In what graph is the lower number better?
Also: "Specifically, [Dave] is using bifacial solar panels– panels that have cells on both sides. In his preferred orientation, one side faces South, while the other faces North. [Dave] is in the Northern Hemisphere, so those of you Down Under would have to do the opposite, pointing one face North and the other South."
Isn't that the same thing? Is one of the sides specifically meant to face the sun? Maybe I'm just not as knowledgeable about solar panels, but what sunlight is being harnessed by the backside of the sun facing panel? Are they catching reflected light, otherwise, they are directly in shadow.
Bifacial panels usually have one side that's a bit more more efficient than the other. The backside can catch reflections, sky light on overcast days, ...
But it's usually more common to orient them east-west, so they have peaks in the mornings and in the afternoon/evening, which combines well with other solar panels that are mounted south-facing, or might even just match your electricity consumption pattern better.
The graph confused me for a moment, but then realized the graph is showing the winter with SNOW on the ground, not the general case. So in the winter the vertical panels produce more power than tilted panels in very specific conditions and depending on how often that occurs, it may make up for the loss in efficiency during other times of the year. I'm guessing the vertical panels gain some advantage of the sun reflecting off the snow and into the vertical panel that the tilted panels do not, especially when the sun is at low angles to the horizon.
If bifacial panels are made so each side is the same making orientation not an issue, then sure, hahahaha (not really. it's a lame joke). If there is a back side, then you absolutely need to reverse the orientation depending on hemisphere. It would be better stated that they need to be pointed towards the equator. If these are literally reversible, it seems like wasted money to me as one side will never produce as much as the reverse does.
The hemisphere talk is a joke, the situation being shown off here is one where there is snow in the ground, which greatly increases the amount of sunlight hitting the backside panel.
This is also in January, when the sun in Ohio is very low in the southern sky. So north/south oriented panels are much more ideal.
If you look at the far right hand bar the B-N/S says 131% which is the highest bar on the chart. So it's producing more than the standard tilted slightly south orientation from what I gather. The legend is a bit hard to read for sure.
I had the same reaction. I noticed the top comment reading "some of us live in the southern hemisphere" so maybe this was a quick edit and not thought through?
Unless one of the sides of the panel is meant to face north, but that doesn't sound likely
One overlooked factor is that as well as getting cheaper, panels are getting more efficient. Commonly installed modules are about 50% more efficient than a decade ago.
Just lots of little tweaks continue to add efficiency, even as they are getting cheaper via lots of other little tweaks.
If you installed a panel today, and assumed a bad case panel degredation over time, then the new panel would be as efficient as the decade old panel was on install even after 40 years of use.
If you assume the new panel has good degredation performance it'll outperform the 2015 panel at install time until roughly 2135!
Or to tie it to the current article, vertical panels installed today outperform perfectly pitched panels from 2015.
There are physics-based limits to how high the efficiency can get with one material, but people are already selling modules with extra layers that work around that limit.
I did some analysis on this recently with a load of simulations. If you ignore the sunlight bouncing back from the surface (and I suspect this might still be the case if you don't ignore it), then the best orientation that maximises winter generation is to have the panels pointing towards the equator and tilted to directly face the Sun at its lowest point at noon in winter. Pointing them lower down (like vertically) reduces the generation. If you're reasonably far from the equator then this is still fairly close to vertical, probably good enough for snow to slide off them.
If you're close to the equator, then vertical North-South panels will generate very little indeed.
Readit News
1. Bi-facial solar panels: can take in sunlight from either end
2. Mounting bi-facials vertically so they can take in sunlight from both directions.
I've been hearing experiments about these for a few years now. There's three main benefits to the vertical arrangement that could, given certain situations, make it more economically valuable:
1. In places with high-albedo snowy winters, this arrangement can boost winter production, which if you have snow, tends to be the energy-heavy time of year.
2. Keeps panels cooler. Panels lose efficiency when they get hot, and by having them vertical, they can run cooler. Losses in less direct sunlight are somewhat offset by efficiency gains from cooler operations.
3. More power during shoulder periods (anti-duck-curve). Especially in places like California that have high solar penetration, prices for excess energy are minimal during peak solar activity. Vertical arrangements give more power in the morning and evening, which is when traditional fields are just ramping up or ramping down. Thus, even if you're making less power overall, you can be making more valuable power by having more production during these ramp-up/ramp-down periods.
Unclear how much of an effect these counter-acting forces actually add, but I understand solar developers are looking into these arrangements.
Notably while the N/S bifacial have an amazing showing in sunny winter day with ground snow (as well a significantly higher resilience against snowfalls), the year round testing he did shows that the performance crater in spring, with half the performance of standard inclined panels, and none of the morning / evening advantages of E/W bifacials.
In the end, the N/S verticals have a worse year round production than every other setup, and significantly worse than standard, but if you live in a location with a fair amount of winter snow and can swing (heh) it a tilting mount could be an interesting configuration for winter.
Deleted Comment
The panels still don't generate any electricity at night of course, but other than that the output is an almost perfect inverse of the conventional equator-facing angled mounted panel output.
Just search for "bifacial solar panels graph".
We currently have:
- summer optimised array: almost flat, 15 degree, optimised for maximum power on sunny summer days, mostly runs our cooling
- winter/morning array. Points SSE, 65 degree incline. Gets great energy in the mornings, and on winter mornings. Performs surprisingly well in overcast conditions. Generates about the same power in midwinter and midsummer.
- winter/afternoon array. Same as the above, but SSW.
18kW total faceplate capacity, in reality we peak at around 5kW, but have that for about six hours of the day for 9 months of the year. Also means I can run three arrays on two MPPTs as the two tilted arrays are basically mutually exclusive as to when they make power.
The other reason for leaning towards vertical panels is cleaning. The flat panels accumulate a crust of crap (pollen, soot, dust) that cements on there fast, and requires vigorous scrubbing to remove. Kills 20% of the capacity unless I get up there with a broom every six weeks. The 65 degree ones I have not had to clean once, as stuff just slides off them.
That, and a pallet of bifacials is now cheaper than a pallet of monofacials.
One big trade off/risk is a large vertical panel essentially becomes a sail in high winds.
A vertical panel has infinite higher efficiency that a flat-mounted one, if a flat-mounted one couldn't be constructed due to floor requirements.
This opens the interesting prospect of hinged vertical pannels that could be adjusted for the season, opening up the V in winter and closing it in summer
https://www.canarymedia.com/articles/solar/how-germany-outfi...
Due to recent issues out there: calculate worst winter peak voltage and make sure there's a healthy margin to the peak allowed safe/no-damage input voltage to the MPPT/charge-controller/inverter.
Panels eat less of their own current at any given operating voltage, the colder they are. And winter mornings after soaking in night cold are worst case conditions for that as they had no time to heat up yet for the first minutes past sunrise.
I guess you also don't need to remove the snow from the panels?
This might work a lot better.
I'm not sure how true that is of course but it does make you think a bit. The optimal place where to put solar panels increasingly is becoming "wherever you can afford to". If vertical space is what you have, why not use it?
People in apartments don't have access to roofs. But they might have balconies. Balcony railings can fit a few solar panels usually.
You can buy solar panels for use on balconies in the supermarket in Germany. They only generate a few hundred watt. But that can add up to close to something like a kwh per day if you get a lot of sun on your balcony. At 40 cents per kwh. That's 12 or so euros per month. I pay about 70 per month currently. And I can get a couple of balcony panels for something like 200-300 euros. And I might get some money back on those even. The idea with balcony solar is that it might offset part of what your fridge uses. You simply plug it into a wall socket and your fridge takes that power instead of from the grid. All safe and approved equipment, the inverter cuts the power if there is no grid power.
I haven't done this (my balcony faces east and only gets a few hours of sun in the early morning). But it's easy to see how this could work.
So, not price parity but also only about a factor of 2 or so. On the other hand, Ali Express panels are about half that UK price at a 10 panel quantity, with unknown shipping.
I'm kind of eyeing the concrete block wall in the back garden currently covered by a hedge.
That said, WW3 terrorism acts may change that. It could be wise to have at least some backup.
Outages are rare enough here in Germany that few people go the extra effort and cost to install the necessary equipment. But with the right equipment (which is available if you go look for it), you can definitely get this installed. In places like Australia, outages are more common and it's generally not that costly to upgrade your setup to support proper islanding and it's more common for people to design their systems for this.
Of course people if feel compelled to prepare for WW III that might be a good motivation. On the other hand, we'll have bigger issues if it comes to that.
I have yet to find conclusive evidence if it is possible to use a small full inverter to drive grid tied inverters, that is, have the grid off capability of a full inverter with the cheap cost of a grid tied inverter. It sounds reasonable, but I don't see anyone doing it.
...that might have been my comment. Or someone else repeating it. I was wrong, I misremembered "in X years solar is projected to be cheaper than wood panels for fences". X being, IIRC, maybe 3 years?
The point still stands, but the fact doesn't. Not til ~2028.
My current strategy for small installations when you have an equator facing wall or fence is slap the panels on it and be done with it.
It turns out these enable a very high specific-power PV cell that adds another even more attractive production curve behind what is happening in vertical bi-facials. See e.g.:
https://ee.stanford.edu/frederick-nitta-koosha-nassiri-nazif...
https://www.arinna.xyz/
Approaches range from straight vertical to flat on the ground: https://erthos.com/earth-mount-solar/
Whole industries are going to pop up to take advantage of the intermittent very cheap electricity. Also there will be a competitive balance between the cost of storage and the "cost" of non-optimally aligned solar panels.
The other discouraging part is that as I understand it it's tricky to build the systems out a little at a time, e.g. start with five panels and no battery, add another five panels and batteries to the mix a few months later, add another ten panels another year later, stuff like that, without ending up with a lot of duplicated equipment and kind of a mess of an installation.
Also: "Specifically, [Dave] is using bifacial solar panels– panels that have cells on both sides. In his preferred orientation, one side faces South, while the other faces North. [Dave] is in the Northern Hemisphere, so those of you Down Under would have to do the opposite, pointing one face North and the other South."
Isn't that the same thing? Is one of the sides specifically meant to face the sun? Maybe I'm just not as knowledgeable about solar panels, but what sunlight is being harnessed by the backside of the sun facing panel? Are they catching reflected light, otherwise, they are directly in shadow.
But it's usually more common to orient them east-west, so they have peaks in the mornings and in the afternoon/evening, which combines well with other solar panels that are mounted south-facing, or might even just match your electricity consumption pattern better.
77% of the ’normal orientation’ per year, but the graph and 131% value is for a day in winter (January 15 this year). At least that’s my read.
I'm still trying to decide if the entire post is trolling or not. Nothing about it sounds sane to me.
Yes, it’s a joke.
This is also in January, when the sun in Ohio is very low in the southern sky. So north/south oriented panels are much more ideal.
I had the same reaction. I noticed the top comment reading "some of us live in the southern hemisphere" so maybe this was a quick edit and not thought through?
Unless one of the sides of the panel is meant to face north, but that doesn't sound likely
Dead Comment
Just lots of little tweaks continue to add efficiency, even as they are getting cheaper via lots of other little tweaks.
If you installed a panel today, and assumed a bad case panel degredation over time, then the new panel would be as efficient as the decade old panel was on install even after 40 years of use.
If you assume the new panel has good degredation performance it'll outperform the 2015 panel at install time until roughly 2135!
Or to tie it to the current article, vertical panels installed today outperform perfectly pitched panels from 2015.
There are physics-based limits to how high the efficiency can get with one material, but people are already selling modules with extra layers that work around that limit.
If you're close to the equator, then vertical North-South panels will generate very little indeed.