As someone who has researched DSM availability across the globe, Google's Solar API is a top contender. Other option is government LiDAR surveys but the coverage, file formats, projections, etc are all fragmented. I think it would be great for the mapping community to create a world wide DSM map tile dataset similar to the ground elevation tile dataset that contour lines and 3D terrain views are generated from. Maybe someone is already working on this?
In the article they show areas where their approach can generate DSM although this is just the potential areas and not the areas where data is already available. :(
Yes. There are planet wide DEM (Digital Elevation Model) datasets which record ground level elevations but no planet wide set for DSM which includes built structures and vegetation.
This is a very impressive refinement of their existing tool, but is this type of advanced calculation of roof-pitch (etc.) still relevant?
Haven't we more or less concluded that a million piecemeal rooftop installations of solar are about the worst way to do it? More complicated and expensive to permit and install, less efficient operation, difficult to repair, difficult to insure, difficult to upgrade, inefficient to integrate into grid, etc.
As someone who recently lost power and water for weeks post Helene, do not discount the power of distributed grids. Distributed core infrastructure will make for much better climate resilience. Don't miss this in your efficiency calculations.
One advantage of distributed solar is that it can at least come online right away and when installed with a battery, can get a home pretty close to being fully self-sufficient (depending on the climate/heating system), whereas the generally much more efficient solar pv power facilities have to contend with backlogs in connecting to the grid, insufficient grid capacity, etc.
But yes, distributed solar will not be the general solution to decarbonizing our energy systems as a whole. Does serve a meaningful role though and there is no reason to not do both.
Australia manages to install rooftop solar at well under half the cost the USA does (most of that is soft costs) and integrate large amounts of it into the grid.
As of lunchtime today, nearly 50% of all electrical generation on the national grid was rooftop solar (and another ~10% was utility-scale solar).
Rooftop solar works just fine if utilities don’t actively try and obstruct its use.
That's a great achievement, but could be stated in a more clear way.
Not 'As of lunchtime' but 'At precisely lunch time'. An hour later it wasn't 50% anymore, and it won't be 50% except at noon for a long time yet. As of the moment I am posting this, solar is 0% and coal is 80%. If Australia cares about global warming they should build nuclear plants and stop generating 70% of their overall power from coal.
It's still remarkable how much solar is growing and I hope it's 100% 24/7 soon!
Or to put it another way: available with a rate of return that makes it sensible for average middle class home owners to say yes to, to the point dirty power sources are having to shut down in some markets (or fiercely lobby through the political system to be propped up).
>...Haven't we more or less concluded that a million piecemeal rooftop installations of solar are about the worst way to do it?
The data shows that you are correct. Utility grid solar provides low cost power and consumer rooftop solar does not and will not. The rooftop solar price is usually hidden because no power source has been as subsidized as rooftop solar. Besides direct subsidies, wealthier home owners have often been paid the retail rate for the electricity they sell to the grid which causes higher electricity bills for those who can't afford to put panels on their roof - sort of a reverse Robinhood scheme.
As the statista.com report says:
>...Rooftop solar photovoltaic installations on residential buildings and nuclear power have the highest unsubsidized levelized costs of energy generation in the United States. If not for federal and state subsidies, rooftop solar PV would come with a price tag between 117 and 282 U.S. dollars per megawatt hour.
Looks like that report is a year old, but I doubt the installation costs have really gone down much since then. (Panel prices come down, but labor costs, etc. don't.)
Yes it's relevant and no we didn't all agree it was a bad idea.
It generates power at roughly the cost of nuclear. It's distributed and resilient. It works around sluggish government and/or corporate monopolies. It reduces transmission requirements. It enables and encourages electrification and time-shifting of load. Adding it at build time can be cheaper than tiling.
It’s generally a good thing and we'll see even more if it as the tech progresses and gets cheaper.
[Given your comment history, as you surely already know...]
Yes and:
With the rise of "virtual power plants" (VPPs), "all the above" (PV, batteries, EVs, water heaters, HVAC, residential geothermal) will be stitched together to create decentralized, more resilient power grids, capable of peer-to-peer power sharing.
Analogy:
Remember the term 90s "convergence" (turrible term)? Describing how the computer (digitization) was becoming the everything tool? VPPs (turrible term) is just the electification of "all the things", unifying all energy (heat, electricity) stuff (source, sink, storage).
It's a good way to anticipate this interation of "convergence". eg VPPs' analog to "traffic shaping" is "load shaping". eg Just like internet is a network of networks, the "intergrid" will be a network of grids. Etc.
It's really easy to see the rough outlines (age of renewable energy) once a person learns of the 100s (1000s?) of puzzle peices currently being assembled. Just reflect on the internet and superimpose those notions onto energy.
It all hinges on how much your infrastructure costs. At the moment something like 1/3rd of your retail cost if delivery. At some point it's 15x cheaper to have 1kW home feed in + battery vs 15kW feed in.
Sounds like a rare case of America's ubiquitous suburbs working out for the environment. Everyone has a "roof" that gets sunlight most of the day, so rooftop solar, while being less efficient, is still a viable candidate.
(Although, if you factor out all the extra driving needed for the suburban life, it would likely still come out negative compared to a proper city.)
Yeah, don’t over look the fact that the thermal demand from space conditioning homes is way higher on a per capita basis in a suburban context compared to an urban context with multi-family housing/apartments etc. There’s just way more air volume to condition per person, generally more inefficient systems, etc.
There are enough panels available to do both and there is no overlap in financing for both. So just do every installation that is economically viable, they don't compete for money or panels.
>> Haven't we more or less concluded that a million piecemeal rooftop installations of solar are about the worst way to do it?
It really depends on what you mean by 'worst'. In terms of land-usage it's the best. In terms of speed-of-deployment it's the best. In terms of distributing capital spend its the best.
In terms of capital return, that will vary from one house to the next because it depends on location, energy consumed (and when), elec prices in your region, grid stability, and so on.
what do you mean by "distributing capital spend"? as in the money to pay for the installations is not concentrated to large utilities? why is that desirable?
The majority of the cost of electricity in most jurisdictions is distribution, not generation. Grid-solar still requires distribution, so it is always going to have significant cost even if the cost of generation is insignificant.
If it can remove the need for a grid-tie, then rooftop solar can be significantly cheaper and more efficient. Can be, but isn't yet, because enough overcapacity and storage to eliminate the need for a grid tie is still too expensive.
This is exactly the challenge. Here in California wholesale solar plant sell power for 0.03-0.04 kwh. Cost at the meter is 0.45/kwh.
Rooftop is competitive with the meter price, but unless you can cut the cord entirely, connection fees and rates will just keep increasing proportionally
With rooftop solar there's a path towards mass deployment that other alternative electricity generation solutions currently lack. Rooftop solar for residential houses doesn't require permits or planning, and can be done by individuals within a reasonable budget, unlike solar farms or rooftop nuclear.
> Rooftop solar for residential houses doesn't require permits or planning
Either you're assuming residential battery storage systems replacing the grid, or your ignoring the connecting rooftop solar to the grid requires permits and planning (the grid may not be able to handle it).
Depends on your cost of electricity. In most places, a solar setup pays for itself long before the warranty runs out max 5-10 years typically (depending on a lot of factors). Even in the US which has a lot of extra cost related to people making things needlessly complicated and costly, lots of people are installing solar and earning their money back.
I can actually get balcony solar here in Germany for about 240 euros. Here's how that works:
- I buy a kit on Amazon. I found several nice ones. This one is rated for 850w and includes cables, inverters and other bits and bobs needed.
- I zip tie the panels to my balcony
- And I plug in the equipment and connect it to a wall socket
The idea is that this would offload some of the power used by e.g. my fridge. Not the same as a rooftop setup obviously and in my case quite pointless since I don't have a lot of sun on my balcony.
But I might actually qualify for a rebate if I do this and get all or most my money back. The government is sponsoring this and landlords can't stop you from doing this. Nor do you need their permission, a permit, or special insurance.
The point is that this stuff is cheap, easy, and pretty much plug and play. Roofs aren't a whole lot more complicated than this from a technical point of view. You need more panels and more expensive equipment and you probably need some professional electricians and installers to do the work.
The rest is just nonsense that relates more to your local government and legislation than anything being inherently expensive or difficult. I'd suggest reminding your local politicians of their responsibilities during the next elections and maybe voting for the ones that aren't being jerks on this front.
Otherwise, solar panels are pretty reliable and generally covered by long warranties. Repairing them is mostly not a thing, somebody would come and simply replace them. I doubt that a lot of solar panel companies and installers are suffering a lot under the enormous burden of this happening all the time for the simple reason that it this isn't a thing.
Balcony solar sounds brilliant and probably has clear ROI. Rooftop solar is an awkward middle between grid-scale solar and balcony solar. Rooftop solar might only make sense in developed countries through subsidies.
Yes, but one back-of-the-envelope calculation (it was a Python program someone wrote up as part of a comment on Slashdot as I recall) demonstrated that if all of New York's roofs were covered in solar panels there would be enough energy to run the city....
I thought we may have concluded that shareholder efficient centralized single point of failure systems are the least robust providers of basic human needs in the face of natural levels of uncertainty.
Grids are pretty much the best solution available because any kind of good/service that can be transported at close to light-speed benefits tremendously from ubiquitous connectivity.
Smarter grids are an even better solution; batteries backing local high-variance demand combined with rapidly negotiated requests for transmission power to meet expected future demand (and then stored in the batteries) reduces (electrical) inefficiency to a minimum.
Residential power demands are highest in the morning and in the evening. That's when people shower, cook, and are generally around using power. Solar peaks at noon.
Maybe when battery prices come down even more. But the cost of grid-level storage are also falling, and wind pretty much only works at grid scale. Grids have to change but won't become obsolete anytime soon.
This is really incredible. If they could plug in local utility prices and come up with estimate for dollars saved per year, that would be an incredible conversation starter for homeowners who might not have considered taking on a home solar project otherwise.
By "Northen" I assume you mean Europe, and (most of) USA?
I live near the 33rd parallel South. Since installing solar my annual grid requirements are around 30% of before solar [1] ‐ even as my actual consumption has risen [2].
As far as "Northern" goes countries in my latitude north (or better) include India, Mexica, all of Africa, most of China, and so on. So for most people living in the north it is compelling [4].
[1] a very large fraction of my grid usage is really cold, wet conditions for 6 weeks in winter. A combination of low generation and high usage for heating.
[2] cooling in summer is free, so we run the aircon a lot more. Plus things like slow-cooking etc are free as well.
[4] my return on investment (grid cost of generated electricity over capital invested) is 16.7%. Projected lifespan is 10 years for battery and inverter, 25 years on panels, 50 years on wiring.
The image processing described is very cool, but I have questions about the application. Google started doing these solar potential estimates about 10 years ago, so let's imagine that they have been developing the capability since about 2010 or so. In that time the cost of PV has fallen by an order of magnitude. Hasn't that settled the question of where PV should be installed? I thought the answer is now "yes" everywhere.
Even assuming 100% solar rooftop coverage is the goal, given limited capacity of raw materials, labor, infrastructure would still necessitate prioritization of when to allocate those things to which places.
But the audience isn't an omnipotent controller of PV panel allocation, it's emergent market participants. Presumably, the market emerges more plentifully in those sunnier places. It's hard to imagine the place where this data is useful to local construction firms who were previously not well-informed (potentially by just walking around with their eyes open).
A lot of new homes are still constructed without solar. Either market participants are sleeping on easy money or the answer isn't a simple "yes, everywhere".
The cost of panels has fallen a lot, but the cost of mounting hardware and installation is still pretty high in the US.
I am sceptical about putting PV on roofs, seems a lot of hassle and waymore expensive then using just flatground: https://en.wikipedia.org/wiki/Bhadla_Solar_Park
Any additional money spent on it, could have helped to install more PV or batteries.
In general yes but due to both taxes/regulations and real issues with the grid it is "easier" to just consume what your produce vs producing and selling to the grid. And since space is limited on most peoples property if you live an urban setting then roof might be the only place to put it. If you got plenty of space though roof is a worse place than the ground from almost every point of view.
How are you calculating that? Solar installations are around $2.50-$3.50 per watt, so $20k would get you 6-8kW. Assuming actual output is 10% of capacity, that's 14-19kWh/day or 5,000-7,000kWh per year. Current residential electricity prices in SF are 38.9 cents per kWh[1], so that's $2,000-2,700 per year in savings, or $40-54k over 20 years. The actual amount saved depends on how much electricity you're consuming during peak times, but I doubt that number is off by a factor of 10.
I find this argument short sighted time and again based on personal life experiences as a former electrician given the life impacting results I have witnessed from power losses.
My electrical experiences are regional to my area in the NorthEast US where long duration events have caused many thousands of US dollars in lost food, tens of thousands of dollars in losses from flooded basements, and when temperatures in Winter often drop below freezing and the power goes out pipes begin to freeze causing even more damage structure wide. In time we will see insurance companies reducing rates for those with local energy storage as the corporate insurance machine catches up to understand the benefits of having such power storage locally. I laugh when people make this exact financial reasoning argument because so few people look at the big picture and fail to comprehend the impacts to their life when that switch on the wall leaves one in the dark. Then again I have designed and architected many successful software systems for high availability and my foundational starting point with any system is always energy. Most of those in society assume that switch will always turn on that light and when it does not then those impacted begin to realize what a "centralized grid" truly means.
Decentralizing the grid is already happening as CA very recently announced any new residences built as of 2026 and beyond must be constructed with PV and storage. Individuals can act in ignorance on the energy problems for now however in time everyone will be forced to participate as the issues continue to compound.
Proactive versus reactive, because by the time it matters it will already be too late.
i've heard of some business models that install these and have you pay what would be the difference to your electric bill to the company until they pay themselves off, not sure if the panels last long enough to make that work though
Yes. In Germany they are selling a lot of models, but none, I mean, really, none asked about the rentability. So I went to a neighbour who just installed his 25kW and was very proud and happy, and asked him, in how many years is the return of investment. Siderated, he could not answer and then a few days later, with a very stern face: 25 years or more because if more people install these, the price that the city is paying for the pumped energy goes down.
So no. 20kw is not the answer. I showed my setup: 3.5kw + big battery. Pays the bill approx 60 70% of the daily usage. Investment payback : 5years.
An interesting use for satellite in future will be accurate estimation of solar power output in the very near future e.g. in the next hour period such that grid operators can adjust storage and demand to get a balanced grid. At the moment we can't do these predictions as we don't know where solar panels are in relation to any passing clouds.
I'm sure you could get that data from public permitting filings. And failing that, train an AI model on scraped Google Maps imagery. I would be surprised if people aren't doing it already.
Readit News
In the article they show areas where their approach can generate DSM although this is just the potential areas and not the areas where data is already available. :(
Thos exact abbreviation is so overloaded that it doesn't hurt to list the words once.
Haven't we more or less concluded that a million piecemeal rooftop installations of solar are about the worst way to do it? More complicated and expensive to permit and install, less efficient operation, difficult to repair, difficult to insure, difficult to upgrade, inefficient to integrate into grid, etc.
You also just have issues like the low chance of having clear skies after a hurricane or a bushfire.
For disaster situation power, a diesel generator is still the cheapest and most reliable option.
But yes, distributed solar will not be the general solution to decarbonizing our energy systems as a whole. Does serve a meaningful role though and there is no reason to not do both.
As of lunchtime today, nearly 50% of all electrical generation on the national grid was rooftop solar (and another ~10% was utility-scale solar).
Rooftop solar works just fine if utilities don’t actively try and obstruct its use.
Not 'As of lunchtime' but 'At precisely lunch time'. An hour later it wasn't 50% anymore, and it won't be 50% except at noon for a long time yet. As of the moment I am posting this, solar is 0% and coal is 80%. If Australia cares about global warming they should build nuclear plants and stop generating 70% of their overall power from coal.
It's still remarkable how much solar is growing and I hope it's 100% 24/7 soon!
One such example: https://www.theguardian.com/environment/article/2024/sep/08/...
Perfect is the enemy of good
The data shows that you are correct. Utility grid solar provides low cost power and consumer rooftop solar does not and will not. The rooftop solar price is usually hidden because no power source has been as subsidized as rooftop solar. Besides direct subsidies, wealthier home owners have often been paid the retail rate for the electricity they sell to the grid which causes higher electricity bills for those who can't afford to put panels on their roof - sort of a reverse Robinhood scheme.
As the statista.com report says:
>...Rooftop solar photovoltaic installations on residential buildings and nuclear power have the highest unsubsidized levelized costs of energy generation in the United States. If not for federal and state subsidies, rooftop solar PV would come with a price tag between 117 and 282 U.S. dollars per megawatt hour.
https://www.statista.com/statistics/493797/estimated-leveliz...
Looks like that report is a year old, but I doubt the installation costs have really gone down much since then. (Panel prices come down, but labor costs, etc. don't.)
It generates power at roughly the cost of nuclear. It's distributed and resilient. It works around sluggish government and/or corporate monopolies. It reduces transmission requirements. It enables and encourages electrification and time-shifting of load. Adding it at build time can be cheaper than tiling.
It’s generally a good thing and we'll see even more if it as the tech progresses and gets cheaper.
Yes and:
With the rise of "virtual power plants" (VPPs), "all the above" (PV, batteries, EVs, water heaters, HVAC, residential geothermal) will be stitched together to create decentralized, more resilient power grids, capable of peer-to-peer power sharing.
Analogy:
Remember the term 90s "convergence" (turrible term)? Describing how the computer (digitization) was becoming the everything tool? VPPs (turrible term) is just the electification of "all the things", unifying all energy (heat, electricity) stuff (source, sink, storage).
It's a good way to anticipate this interation of "convergence". eg VPPs' analog to "traffic shaping" is "load shaping". eg Just like internet is a network of networks, the "intergrid" will be a network of grids. Etc.
It's really easy to see the rough outlines (age of renewable energy) once a person learns of the 100s (1000s?) of puzzle peices currently being assembled. Just reflect on the internet and superimpose those notions onto energy.
Thanks for listening.
Home solar is a big win, and if nothing else allows capital to be sourced from a million home owners.
Centralized solar is a big win, generating grid power Erich is obviously important.
It's not a question of either, it's a question of both.
(Although, if you factor out all the extra driving needed for the suburban life, it would likely still come out negative compared to a proper city.)
It really depends on what you mean by 'worst'. In terms of land-usage it's the best. In terms of speed-of-deployment it's the best. In terms of distributing capital spend its the best.
In terms of capital return, that will vary from one house to the next because it depends on location, energy consumed (and when), elec prices in your region, grid stability, and so on.
If it can remove the need for a grid-tie, then rooftop solar can be significantly cheaper and more efficient. Can be, but isn't yet, because enough overcapacity and storage to eliminate the need for a grid tie is still too expensive.
Rooftop is competitive with the meter price, but unless you can cut the cord entirely, connection fees and rates will just keep increasing proportionally
More durable for individuals in the face of large scale failures. You're paying for something real there.
Either you're assuming residential battery storage systems replacing the grid, or your ignoring the connecting rooftop solar to the grid requires permits and planning (the grid may not be able to handle it).
I can actually get balcony solar here in Germany for about 240 euros. Here's how that works:
- I buy a kit on Amazon. I found several nice ones. This one is rated for 850w and includes cables, inverters and other bits and bobs needed.
- I zip tie the panels to my balcony
- And I plug in the equipment and connect it to a wall socket
The idea is that this would offload some of the power used by e.g. my fridge. Not the same as a rooftop setup obviously and in my case quite pointless since I don't have a lot of sun on my balcony.
But I might actually qualify for a rebate if I do this and get all or most my money back. The government is sponsoring this and landlords can't stop you from doing this. Nor do you need their permission, a permit, or special insurance.
The point is that this stuff is cheap, easy, and pretty much plug and play. Roofs aren't a whole lot more complicated than this from a technical point of view. You need more panels and more expensive equipment and you probably need some professional electricians and installers to do the work.
The rest is just nonsense that relates more to your local government and legislation than anything being inherently expensive or difficult. I'd suggest reminding your local politicians of their responsibilities during the next elections and maybe voting for the ones that aren't being jerks on this front.
Otherwise, solar panels are pretty reliable and generally covered by long warranties. Repairing them is mostly not a thing, somebody would come and simply replace them. I doubt that a lot of solar panel companies and installers are suffering a lot under the enormous burden of this happening all the time for the simple reason that it this isn't a thing.
Smarter grids are an even better solution; batteries backing local high-variance demand combined with rapidly negotiated requests for transmission power to meet expected future demand (and then stored in the batteries) reduces (electrical) inefficiency to a minimum.
Maybe when battery prices come down even more. But the cost of grid-level storage are also falling, and wind pretty much only works at grid scale. Grids have to change but won't become obsolete anytime soon.
Once you do the math in a Northern country (sans subsidies) it's not as compelling as you might think.
https://pv-magazine-usa.com/2022/11/16/tackling-soft-costs-a...
I live near the 33rd parallel South. Since installing solar my annual grid requirements are around 30% of before solar [1] ‐ even as my actual consumption has risen [2].
As far as "Northern" goes countries in my latitude north (or better) include India, Mexica, all of Africa, most of China, and so on. So for most people living in the north it is compelling [4].
[1] a very large fraction of my grid usage is really cold, wet conditions for 6 weeks in winter. A combination of low generation and high usage for heating.
[2] cooling in summer is free, so we run the aircon a lot more. Plus things like slow-cooking etc are free as well.
[4] my return on investment (grid cost of generated electricity over capital invested) is 16.7%. Projected lifespan is 10 years for battery and inverter, 25 years on panels, 50 years on wiring.
The cost of panels has fallen a lot, but the cost of mounting hardware and installation is still pretty high in the US.
Deleted Comment
In Germany we already have large distance energy transfer problems.
And PV is so cheap now + battery, you get independence / real freedom out of the box.
If you have valuable space on the ground and want to remove the utilization of it, sure but I prefer it on the roof were it doesn't do that.
But yes next to autobahns or other smart locations yes put it on the ground.
But when I invest in myself I will not sponsor pv somewhere else
$20k upfront cost.
$4k in savings over 20 years.
That's an implied rate of return of 0.9% annually.
No thanks.
1. https://www.bls.gov/regions/west/news-release/averageenergyp...
https://sunroof.withgoogle.com/
Plus, are you counting in inflation of electricity prices in those 20 years? I'm sure electricity isn't going to get cheaper
My electrical experiences are regional to my area in the NorthEast US where long duration events have caused many thousands of US dollars in lost food, tens of thousands of dollars in losses from flooded basements, and when temperatures in Winter often drop below freezing and the power goes out pipes begin to freeze causing even more damage structure wide. In time we will see insurance companies reducing rates for those with local energy storage as the corporate insurance machine catches up to understand the benefits of having such power storage locally. I laugh when people make this exact financial reasoning argument because so few people look at the big picture and fail to comprehend the impacts to their life when that switch on the wall leaves one in the dark. Then again I have designed and architected many successful software systems for high availability and my foundational starting point with any system is always energy. Most of those in society assume that switch will always turn on that light and when it does not then those impacted begin to realize what a "centralized grid" truly means.
Decentralizing the grid is already happening as CA very recently announced any new residences built as of 2026 and beyond must be constructed with PV and storage. Individuals can act in ignorance on the energy problems for now however in time everyone will be forced to participate as the issues continue to compound.
Proactive versus reactive, because by the time it matters it will already be too late.
Deleted Comment
So no. 20kw is not the answer. I showed my setup: 3.5kw + big battery. Pays the bill approx 60 70% of the daily usage. Investment payback : 5years.
They're a terrible deal for those companies investors though.
Presumably at some point they go bankrupt and sell your roof at auction??? weird setup
A lot of the time such companies pray on people on stupid plans (or those paying thru the nose for "exclusively renewable") power.
Global Solar Power Potential Map - https://news.ycombinator.com/item?id=40303570 - May 2024