The reason they are tilted is to maximize irradiance hitting the panel. At a 0 degree angle (flat on the ground) you get a a lot around noon and then very little.
This approach surely reduces land usage but what is the output per acre?
I’d be really surprised if it’s higher than with tilted modules.
The amount of power landing on an acre is fixed, what you can achieve by tilting is having less solar panel surface area per ground cover area. If solar panels are cheaper than the mounting hardware (wow) then there is no reason not to let them lie flat on the ground (it's not as if the racks were holding them above tree shadows, or anything).
This is a great way of thinking about it, but don't you lose a bit more due to increased reflection from the glass surface at low incident angles? Probably not enough to make a difference a low latitudes in the summer, but at high latitudes in the winter I think it might be a significant difference: https://en.wikipedia.org/wiki/Fresnel_equations#/media/File:...
Partially answering myself, 'sacred_numbers' posted a link elsewhere in this thread that suggests this effect might be quite small: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6611928/. The paper concludes that for a cell with a good Anti-Reflective Coating (ARC), the reduction in efficiency due to reflection at a 60 deg incidence is only 2%.
On the other hand, the incidence for a flat mounted panel beyond 37 degrees of latitude on the winter solstice is greater than 60 degrees, and it's not clear (to me at least) how well the ARC on an average panel will continue working after years of outdoor usage. My guess is reflection is probably a real issue, but not a stopper unless one is already in a marginal situation.
I'm at 54N and my output has been 0 for the past month as we've had a lot of snowfall. My panels are at 20 degrees, so even in the few sunny days we've had it's not been enough to melt the snow. A steeper angle probably would have cleared it a few times.
Usually the beginning of the year has more sun but it's colder, so I'll see what happens then.
The solar radiation wattage per unit of surface area is dependent on the angle that surface is to the sun. The angle is dependent on the season and time of day, so the amount of power is not fixed.
What the comment wanted to say is that the power per unit of ground surface area is fixed for a given location and time, i.e. it does not matter [1] whether you cover a given area with panels angled towards the sun or lying flat on the ground, at least if one only looks at the available power. There is of course a difference in the solar panel area required to cover a given area of ground surface - solar panels lying flat on the ground will obviously have to have the same area as the ground surface area while panels angled towards the sun will only require a fraction of the ground surface area equal to the sine of the angle of the sun above the horizon.
[1] For a sufficiently large area so that effects on the edge are negligible.
You could write a few pages of all the things that the power available depends on, but you don't need to because it's fixed relative to the variables under consideration.
Per unit of panel surface area, not per unit of land area. If the sun is coming in at an angle, you'd be able to collect all that's available with less panel area than total land area by angling them (or equivalently, in this new configuration you need more panel area than you otherwise would), but in their estimation, it's cheaper to just get more panels than it is to buy and install racks.
>The solar radiation wattage per unit of surface area is dependent on the angle that surface is to the sun.
A tilted solar panel casts a shadow that is bigger than its actual area. Mounting the panel flush to the ground means it casts a shadow exactly equal to its area.
The shadow represents the captured sunlight so the first panel covers more surface area than the second panel, which allows you to reduce the number of panels to cover the same amount of surface area. The entire point of this article is that you can just put the saved costs into buying more solar panels.
Used solar panels are very cheap but usually only the solar panels are replaced and the mounts are kept and fitted with new panels. So for companies that want to use used panels their primary cost is actually in the mounting hardware and not the panels.
> If solar panels are cheaper than the mounting hardware (wow)
I'm surprised this surprises people... Every electronics hobbyist knows that electronics are cheap as dirt while any kind of box, mount, rail or whatever is BY REALLY FAR the most expensive part of a project, even when buying massivly mass produced cheap Chinese junk.
You are surprised that this surprised people because electronic hobbyists know this? Most people are not electronic hobbyists so this should probably not surprise you
I just find it interesting, the difference different perspectives can make, especially on a website where people are often bikeshedding things they have no experience with.
Texas is pretty far south. If you use https://pvwatts.nrel.gov/pvwatts.php there is about a 9% increase in total output over the year for optimal tilt(27 vs 0) but then you also need to space modules.
There is hourly data if you are interested but even Jan 1 the panels produce for ~7-8 hours. The 3 hour around noon it's about 1/2 the output for the day (for Jan 1).
> you get a a lot around noon and then very little.
That's a little harsher than reality. You get a very pretty bell curve. I have a flat panel on the roof of my RV and I track the output over time. I'm not 100% how much of the loss in output is because the incidence to the panel is changing, or because the light from the sun is going through more atmosphere. Probably a little of both, but in any case the panel is still plenty useful even when not pointed directly at the sun.
With tilted modules, you'd normally space them out quite a bit so the shadows of one aren't falling on the module next to it. If they're all flat, that's not a problem so you can space them closer. So, it makes sense that they'd get more power per acre than the conventional approach -- the panels are individually less efficient, but there's a lot more total solar panel area per acre.
That might not always be a good tradeoff, but maybe at least some of the time it is.
I expect that they are getting lower output per acre, but in places where land is cheap and as solar panels continue to get cheaper, the money saved on building the support structures could be worth those losses.
They don't claim to outperform fixed-tile or SAT on that KPI. They claim to reduce upfront cost of installation, construction time, and general project risk.
Seems lying them flat also makes their cleaning robot able to easily maneuver, meaning they don't need to leave any space in between panels for humans to perform maintenance. Pros: reduces land usage as you mention, but also less humans needed for maintenance.
The article claims it's much higher output per acre:
> conventional solar technologies, which typically require five to 10 acres of land per megawatt of capacity. Erthos claims that its mounting scheme requires less than 2.5 acres per megawatt.
They claim the power per acre is 4x higher than tilted panels. Seems like a stretch, but I don't know how bad the density is in tilted installations. I guess I have seen some where you can drive between rows
Density in tilted installations is quite bad. If you want to capture morning and evening sun at an optimal angle you have to space the panels out a lot, like 5-10 panel heights. You can have them closer, but then you get shading, which defeats the purpose of tilting the panels.
The gov optimization function is to maximize production not employment. This is an ongoing fallacy in the political narrative but the unseen consequences of making up jobs is overall lower purchasing power.
Hey ! I'm an engineer with experience building utility-scale solar and backend software at bay area companies.
I'm building ClimateCap (https://www.climatecap.io/) -- software to collect data and develop intelligence on climate-related risks and opportunities for climate finance.
My belief is that climate change is an incentives problem.
Currently, incentives vary geographically but they'll converge when physical and transitional risks are priced into every business model.
The allocation of capital that follows is estimated to be ~$1T USD/year for the foreseeable future (Source: https://fsb-tcfd.org/).
I'm launching a beta feature called "Climate-Related Financial Disclosures", giving anyone access to a list of climate risks and opportunities disclosed by US companies in their latest financial filings (10K, SEC), see https://www.climatecap.io/app
The sole motivation of this launch is to talk to people in the space and build a product roadmap along the vision above.
Drop me a note if you have feedback or ideas of who I should talk to.
Renewable energy is the most likely solution to this problem. Wind and solar are ready to scale and take over electricity generation.
Wind, solar, batteries, and transmission lines. That is a solution we could deploy today and it is being deployed today. There is a further backlog of wind projects in the US that could be unlocked if we approve transmission lines (like SOO Green) to bring power from the Midwest to the Northeast.
The amount of power that we produce from nuclear in the US basically hasn't changed in 20 years. Wind has gone from almost zero to 8.4% of our total production in 15 years. Solar has gone from almost zero to 2.3% in 5 years. I expect that the US will be producing more power from wind than coal in 5 years.
"Bipartisan federal mandates to scale nuclear energy is the only real solution to this problem"
Where to start? Bipartisan implies 'America', which is not 'the world'.
Scaling up nuclear energy implies even more energy consumption rather than to do the obvious: shut down coal and gas fired plants and cap the per capita energy budget to something reasonable.
Finally, nuclear instead of solar/wind is going to push yet another problem down to future generations.
Lower energy consumption is politically less feasible to implement, regressive and undesirable.
Bipartisan refers to cooperation of two political parties, not 'America'. But sure, few other countries have only two major political factions. More generally I meant to promote nuclear energy in political cooperation.
You are right in that the obvious is shutting down coal and gas plants.
The less obvious is that natural gas generation is very cost competitive. Solar/Wind are not viable solutions at the deployment velocity we need to achieve targets.
Also, they are not base load, so you are assuming storage is available and cost-competitive which seems to be 5-10 yrs from now.
An honest conversation of decarbonizing electricity has nuclear front and center.
You are a couple of years behind the times when it comes to your knowledge of the cost effectiveness of solar and wind. They are $ for $ competitive with nuclear, and are being rolled out at scale. 8 MW onshore turbines are now pretty normal, larger ones are on the drawing board, and in the offshore wind market there are now 15 MW turbines.
Base load can be provided through carbon neutral sources, such as the burning of rest-mass left over from crop production. Smart control of appliances is another way in which the need for baseload power could be reduced, allowing for increased consumption to co-incide with periods of higher (or even excess) power generation, and high voltage DC has made it cost competitive to route electricity across larger distances than before allowing an excess in windpower from one location to be moved with relatively little loss to places where there is a shortage.
Storage is entirely optional in this scheme, but we already have more and more battery storage coming on-line in the form of the expanding fleet of electric vehicles which can provide a large sink.
Energy consumption correlates to qualify of life because that's the society that we've built. But it need not be so, not every source of pleasure or quality of life needs a combustion engine or a plug.
'Base load can be provided through carbon neutral sources, such as the burning of rest-mass left over from crop production.'
This statement is very uncalibrated. Biomass is possible just as much as tidal power but that doesn't make it viable for scale. It's not even part of the conversation.
'Smart control of appliances is another way in which the need for baseload power could be reduced'
Wrong. Smart control of appliances is used to shift demand from peak load not base.
Storage is not optional to make renewables base load.
'But it need not be so, not every source of pleasure or quality of life needs a combustion engine or a plug.'
You are obviously trivializing quality of life. High energy consumption means access to quality products and services in food, transport, education, entertainment and healthcare at minimum.
Nonproliferation agreements alone mean your scheme will never work. I prefer to solve problems with the available means rather than to fantasize about a world that could be, it tends to get more and faster results.
FWIW baseload is provided today by biomass augmented plants all over Europe (except for France, which does rely predominantly on nuclear. It's not yet the largest fraction but it is definitely moving the needle.
Smart control of appliances can be used to shift demand from peak, but it can also be used to shift demand away at times that baseload would have to be increased for baseload generators that are slow to ramp up (such as: nuclear).
As for storage not being optional, we are very far away from having excess power with such regularity that storing it is cheaper than reducing generating capacity. In other words we can safely ignore this problem until orders of magnitude more renewable energy generation capacity has been installed.
It looks to me like you are heavily personally invested in seeing nuclear (fission, presumably) based energy no matter the disadvantages, which are numerous and which leave us with a serious problem in terms of waste removal.
The easiest path to reducing our carbon emissions is to electrify everything (notably: transportation and heating) and clean up the power grid. That is going to require doubling the size of the electrical grid in the next 20 years. There's a lot of wind and solar that we're going to need to be bringing online in the next couple of decades!
Reminds me of Carmack and Romero doing their thing with shareware games - true hackers, no fucks given, brilliant engineers, screw the corporate bullshit and get on with the business.
Speaking of sheer skills, take a look at geohotz twitch streams. Just the breadth of topics is fun to watch: making your own crypto, hacking the neural chip, low size encryption.
I’d love to see folks plan to monetize their product from the get go and not as an afterthought.
They should get measurable, direct compensation for the value created for others — be that saved time, joy or something else.
I feel there’s this quasi-apologetic approach to selling software when there should only be respect for those who can create value for others by their own creative and productive ability.
https://streetcleaningparking.com