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.
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.
Utility scale fields tend to have single axis trackers which can optimize output. They are expensive though. I wonder if a manual rack that could lock at 30 or 90 could work and be cost effective.
Come on: "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."
I read somewhere (maybe in Dave's youtube comments) that the price of fencing is high enough that some folks have used bifacial vertical solar panels as a fence.
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.
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.
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.
> 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?
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.
This setup almost certainly took more carbon to make than it will ever replace. This is usually true anywhere it snows regularly. There are a couple of exceptions, but unless you are above 7000ft of elevation you are just making the problem worse. This guy should donate this setup to someone in Mexico where it would make sense.
This might have been correct 30 or 40 years ago, but energy payback time for solar panels has been only a few years since at least the last millennium.
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.:
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.
>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.
I wonder why 30 deg was chosen. If you want to maximize energy production in the winter they should be installed more vertically so that for most of the winter the angle between the sun rays and the panel is around 90 deg.
Is the title (here and on the article) supposed to say "outstanding" as in "amazing! wonderful!" or is it deliberately "out standing" as in ... standing...out...actually, I don't even know if this is a valid phrase.
bifacial panels indeed produce more electricity. but does it justify the cost increase?
simply speaking if bifacial panels cost 2x, do they produce anything close to 2x electricity?
Why not mount the double sided vertical panels edge towards the sun with a mirror panel on each side? Add some passive cooling channels between the panels, or even boost it with a small fan. I would think that might result in even better gains instead of having one side wirh full sun and the other eith indirect sun.
We need more data on bifacial performance in order to simulate the performance. I've done some experiments with vertical bifacial TOPCon panels, and the lower production vs 45-degree tilt seems to be offset by the lower mounting costs.
I run a solar company, and for ground mount systems the cost of the frames and foundations is more than the panels. With vertical PV it doesn't matter if power production is maximized, what matters is return on investment.
I’m not sure I am understanding how 77% is totally awesome if tilted panels produce 90%, but could the vertical panel efficiency not be improved by putting some reflective material at a tilt towards the vertical panels?
Also, couldn’t the tilted bi-sided panels also have some reflector send light to the rear side?
> 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.
38 comments
[ 2.9 ms ] story [ 51.1 ms ] threadAlso: "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.
Approaches range from straight vertical to flat on the ground: https://erthos.com/earth-mount-solar/
That is not the kind of thing I come here for.
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.
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.
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.
I guess you also don't need to remove the snow from the panels?
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/
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.
...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.
I run a solar company, and for ground mount systems the cost of the frames and foundations is more than the panels. With vertical PV it doesn't matter if power production is maximized, what matters is return on investment.
Also, couldn’t the tilted bi-sided panels also have some reflector send light to the rear side?
Nice example of hacker humor.