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Rooftop solar never really made sense in the big picture kind of way. It's about 2x the cost of non-rooftop solar, so why should we be putting it on roofs when

Rooftop solar never really made sense in the big picture kind of way. It's about 2x the cost of non-rooftop solar, so why should we be putting it on roofs when there is still plenty of non-roof space to put it? If we get to a point where we've run out of room for solar...then sure, roofs are great (although residential roofs should probably be the last roofs after big, flat industrial/commercial roofs), but the only reason it ever made sense to begin with was extremely large subsidies that probably should have gone to other renewable efforts.

emmet 3y ago
If you want private panels in pretty much any country outside of America, they're going to have to go on the roof as we don't exactly have the land to waste elsewhere.
- adrianN 3y ago
  Here in Germany we waste about 2.4 million hectares on „energy crops“. That’s enough to cover a large fraction of Germany’s primary energy consumption if it were used for solar instead.
  - arunharidas 3y ago
    The foolish move by the German government to close down all the nuclear reactors. The German government is weird.
    - adrianN 3y ago
      It would have been nice to turn off coal first, but it doesn’t change what we need to do for renewables.
    - pgeorgi 3y ago
      Or history is more complex than a sound bite. Getting Germany off nuclear has been in the making since the 1980s, and a big factor was fighting corruption. We still have a glowing mess from those days, waiting another 80 years until it can be cleaned up.
- KoftaBob 3y ago
  I think the commenter was implying that rather than putting it on the roof of people's homes, the focus should be on utility-scale solar power stations.
  - Tade0 3y ago
    Which doesn't make too much sense outside of the US, where land isn't nearly as cheap.
    - konschubert 3y ago
      It makes sense in any country that has agriculture. Solar produces 10x as much power per area than energy crops. And other than with crops, you can have sheep grazing and have a functioning meadow ecosystem develop below the panels.
      - emmet 3y ago
        What are the upfront & maintenance costs of solar vs crops on that kind of scale? I'd hazard a guess it's a little more than 10x. Also, how are you planning to grow meadows under solar panels without any sunlight?
        konschubert 3y ago
        I’m honestly super excited about you asking because I think I’ll be able to change your mind with a single picture: https://cdn.arstechnica.net/wp-content/uploads/2021/10/GettyImages-1226802459-800x533.jpg https://cdn.arstechnica.net/wp-content/uploads/2021/10/Getty... The sun moves, and therefore the shadows move. And you need some space between the panels anyways, so they don’t shade each other. Also, grass can grow in the shadow! The cost of installation is not a problem, because the ROI is greater than the interest on a loan. That’s what banks are for!
        emmet 3y ago
        You are correct, this has changed my mind as it is a lovely weird photo that I have enjoyed.
- kragen 3y ago
  you say 'If you want private panels in pretty much any country outside of America, they're going to have to go on the roof as we don't exactly have the land to waste elsewhere.' https://www.worldometers.info/geography/7-continents/ https://www.worldometers.info/geography/7-continents/ says the population density of north america is 28 people/km², and south america is 25. meanwhile, europe is 33, africa is 49, asia is 153, "australia/oceania" (???) is 5, and antarctica is 0. so basically the population density of europe is the same as america, africa is just a little bit higher, asia is much higher, and australia is much lower possibly by 'pretty much any country outside of america' you meant either nigeria or singapore but let's consider the worst case continent, asia. 153 people per square kilometer means 6500 square meters per person. hopefully you are aware that the average home size in asia is not 6500 square meters or even 65 square meters, and that a substantial fraction of people live in apartment buildings which share a roof. so the vast majority of land even in asia is not roofed. this is also obvious from looking at any satellite photo. but enormous numbers of people live in houses with gardens or even farms attached if we assume a 15% average solar capacity factor and 21% efficient solar panels, 6500 square meters per person is 200 kilowatts per person. current world marketed energy consumption is something like 2, 2½ kilowatts per person. that's still too much to put on the average roof but it's not exactly a major fraction of the total land area either even nigeria is only 250 people per square km you're right about singapore tho
anamax 3y ago
Residential solar has one huge advantage over utility solar - RS lets people virtue-signal. In other words, part of the payback/value is letting people say/think "I'm a good person." We can argue about whether the additional solar demand due to virtue-signaling had good effects but it did produce additional demand.
- trilbyglens 3y ago
  Contrary to all that, I know many people who are now basically immune to power grid issues in the us due to their solar and storage capacity. A friend in Oakland was running off of local storage for 8 days last year while the rest of his block was scrambling to buy generators.
  - gorbypark 3y ago
    One of the issues I have with "rooftop solar" is that it's usually sold by and installed by companies who are there to make a quick buck and they don't really explain the details to customers. Besides the predatory pricing and loans, and the blatant lying about payback periods, one big thing is the lack of technical details. The amount of people who don't understand that their new solar install is useless when the grid goes down is astounding.
  - elzbardico 3y ago
    Your friend is probably rich or very frugal on his power consumption
cybrox 3y ago
It doesn't make sense if you effectively rent the panels, which means they have to come down again.
- anamax 3y ago
  Whether or not the panels "have to come down" depends on who pays. If the solar company has to pay, it might not bother at the end of the lease term. This can turn into a very low price to sell the panels at that time.
adrianN 3y ago
It’s nice to have generation close to consumption because you save on transmission infra.
- elzbardico 3y ago
  No. You don’t. The sun doesn’t shine 24/7.
  - adrianN 3y ago
    Demand at night is much lower.
xyzzy123 3y ago
It's a trust issue. People don't trust their utilities, residential solar is (among other things) a hedge. Basically, "how much would you pay to limit how much $powerco can screw you in future?". Human nature means a lot of people will willingly pay double for that.
- elzbardico 3y ago
  Most people have grid-tie systems. If the power is out, they are down too. Only very rich people have money to buy battery storage enough to be off grid and then this kind of system is not what those companies usually lease. If you’re concerned about blackouts a gas natural generator makes a lot more sense economically speaking
  - xyzzy123 3y ago
    This is factually true but my claim is that what motivates people is a desire for greater energy security (EDIT: where improved price stability is one aspect of that, as konschubert points out).
    - konschubert 3y ago
      It also means you're less affected by rising prices. (Not that I expect rising prices, but others do)
- robin_reala 3y ago
  “People don't trust their utilities” is a strong claim that I assume is very dependent on your location. I think I’ve had maybe two hours total of no electricity in the last five years?
  - xyzzy123 3y ago
    Yeah I admit this is pretty situational - the U.S. I don't know much about - but NZ, Australia and most of Europe, consumer sentiment is that we are getting slugged - I don't have a survey to hand but I'm confident I could dig something up (EDIT: e.g: https://www.energymagazine.com.au/energy-survey-reveals-rising-consumer-concerns/ https://www.energymagazine.com.au/energy-survey-reveals-risi...) In the last 5 years, has your kwh price increased? By more or less than inflation? If utility scale solar takes off, do you expect that future prices will reflect a) capital and operating costs plus a fair margin or b) whatever the market will bear?
reacharavindh 3y ago
I’m going to answer your “financially nonsensical” argument from personal situation. I live in the Netherlands. Sure, we have a reliable power grid that doesn’t go offline for hours or any frequently to make a case for grid backup, but the power companies here charge heck of a lot of money for power. Think about it. The utility company commissions a solar farm (lower cost than roof top solar), but surely hire a 3rd company to operate the farm ($), and then the utility company wants to make $ for their shareholders, therefore, we end up paying a lot of € to cover these. Now, I have as manay panels as I could on my roof (10) that generates more than my average use in the Summer. I run a heat pump that can heat & cool and Ioperate it when the sun is shining. I do laundry when the sun is shining. Because of net metering, my grid usage practically cancels out against my solar energy production. When the net metering subsidy goes away, I’ll install a reasonably sized LFP battery at home to smooth out day/night patterns, and possibly covering the occasional cloudy days right after a sunny day. No power costs from April to September already pays the cost of my panels in just 5 years. It is free money(as in I save it from going from my pocket to the utility company and their shareholders). So, it does make sense. Atleast in many parts of the world. If you live in a part of the world with super reliable grid _and_ low prices, or you’re so rich as to not care, then probably, it may not make sense to you :-) I was just talking about it with some friends from South Africa. They said almost every household there sort of needs to be energy independent because the power company is in the ruin. So, solar + batteries it is. What would you do otherwise?
- yourusername 3y ago
  >Think about it. The utility company commissions a solar farm (lower cost than roof top solar), but surely hire a 3rd company to operate the farm ($), and then the utility company wants to make $ for their shareholders, therefore, we end up paying a lot of € to cover these. You missed the largest reason home solar can be competetive and that is taxes. 11 cents per kWh and 3 cents sustainability charge and then 21% VAT over the cost price + taxes. And then the government mandates the energy companies have to buy your energy for the same price they sell you energy. So as with many thing here it only makes sense because the government has completely distorted the market.
  - 3y ago
Kon5ole 3y ago
>Rooftop solar never really made sense in the big picture kind of way. I think it's in the big picture it actually does make sense. True it's not the cheapest, but it is the fastest way to actually get solar panels into sunshine and start solving our problems. The additional cost is paid mostly by "volunteers" instead of having to raise taxes or wait for some corporation to make a move, there is no NIMBY-problem since it's actually the BY-owner who makes the decision. You can mobilize thousands of companies (solar panel installers) at once all around the country. Rooftop solar grows by about the same as a nuclear power plant per year in some countries. Finally the resulting power generation is geographically distributed so that no single rain cloud can cover the entire "power plant". I think larger projects run by governments and large corporations should be focused on generating gas or building battery storage, so that some of that cheap rooftop solar and other renewables can be stored for nighttime and winter, instead of being sold for negative prices at certain times.
alkonaut 3y ago
What's plenty of space? I have perhaps 3-400 sqm of lawn. I'm not going to use 50-100 of that for solar when I have that amount of roof that is otherwise wasted space. I agree that perhaps domestic installations might not be the best idea because you need the same equipment repeated at every home, that could otherwise be centralized at a plant. But for resilience it's pretty neat. If I had more than say one power outage a year lasting more than an hour, I'd definitely be looking at it. I can see why South Africa is a big market (lots of sun, frequent power outage). Perhaps the middle ground between massive scale and domestic scale would be community sized plants serving (say) 100-1000 households.
kragen 3y ago
yes, it's collectively irrational behavior, just like warfare. but it's often individually rational behavior (like defending your country when it's invaded, in some cases) because electric power utilities commonly have monopolies, which causes two problems: 1. they become single points of failure, and their risk tolerance for outages may not match yours, so you may end up either paying excessive costs for reliability you don't need, or experiencing an outage risk you can't tolerate. or they may have outage risks which you can't solve by dumping money on them, such as corruption 2. they sometimes try to extract monopoly rents there are also coordination problems around things like time-of-usage billing. solar power is free during the day, but your utility provider may not be willing to deliver it to you for the extremely low marginal price of transmission and distribution; they may be legally obligated to charge you the same price as at midnight, for example

emmet 3y ago

If you want private panels in pretty much any country outside of America, they're going to have to go on the roof as we don't exactly have the land to waste elsewhere.

adrianN 3y ago
Here in Germany we waste about 2.4 million hectares on „energy crops“. That’s enough to cover a large fraction of Germany’s primary energy consumption if it were used for solar instead.
- arunharidas 3y ago
  The foolish move by the German government to close down all the nuclear reactors. The German government is weird.
  - adrianN 3y ago
    It would have been nice to turn off coal first, but it doesn’t change what we need to do for renewables.
  - pgeorgi 3y ago
    Or history is more complex than a sound bite. Getting Germany off nuclear has been in the making since the 1980s, and a big factor was fighting corruption. We still have a glowing mess from those days, waiting another 80 years until it can be cleaned up.
KoftaBob 3y ago
I think the commenter was implying that rather than putting it on the roof of people's homes, the focus should be on utility-scale solar power stations.
- Tade0 3y ago
  Which doesn't make too much sense outside of the US, where land isn't nearly as cheap.
  - konschubert 3y ago
    It makes sense in any country that has agriculture. Solar produces 10x as much power per area than energy crops. And other than with crops, you can have sheep grazing and have a functioning meadow ecosystem develop below the panels.
    - emmet 3y ago
      What are the upfront & maintenance costs of solar vs crops on that kind of scale? I'd hazard a guess it's a little more than 10x. Also, how are you planning to grow meadows under solar panels without any sunlight?
      - konschubert 3y ago
        I’m honestly super excited about you asking because I think I’ll be able to change your mind with a single picture: https://cdn.arstechnica.net/wp-content/uploads/2021/10/GettyImages-1226802459-800x533.jpg https://cdn.arstechnica.net/wp-content/uploads/2021/10/Getty... The sun moves, and therefore the shadows move. And you need some space between the panels anyways, so they don’t shade each other. Also, grass can grow in the shadow! The cost of installation is not a problem, because the ROI is greater than the interest on a loan. That’s what banks are for!
        emmet 3y ago
        You are correct, this has changed my mind as it is a lovely weird photo that I have enjoyed.
kragen 3y ago
you say 'If you want private panels in pretty much any country outside of America, they're going to have to go on the roof as we don't exactly have the land to waste elsewhere.' https://www.worldometers.info/geography/7-continents/ https://www.worldometers.info/geography/7-continents/ says the population density of north america is 28 people/km², and south america is 25. meanwhile, europe is 33, africa is 49, asia is 153, "australia/oceania" (???) is 5, and antarctica is 0. so basically the population density of europe is the same as america, africa is just a little bit higher, asia is much higher, and australia is much lower possibly by 'pretty much any country outside of america' you meant either nigeria or singapore but let's consider the worst case continent, asia. 153 people per square kilometer means 6500 square meters per person. hopefully you are aware that the average home size in asia is not 6500 square meters or even 65 square meters, and that a substantial fraction of people live in apartment buildings which share a roof. so the vast majority of land even in asia is not roofed. this is also obvious from looking at any satellite photo. but enormous numbers of people live in houses with gardens or even farms attached if we assume a 15% average solar capacity factor and 21% efficient solar panels, 6500 square meters per person is 200 kilowatts per person. current world marketed energy consumption is something like 2, 2½ kilowatts per person. that's still too much to put on the average roof but it's not exactly a major fraction of the total land area either even nigeria is only 250 people per square km you're right about singapore tho

anamax 3y ago

Residential solar has one huge advantage over utility solar - RS lets people virtue-signal. In other words, part of the payback/value is letting people say/think "I'm a good person." We can argue about whether the additional solar demand due to virtue-signaling had good effects but it did produce additional demand.

trilbyglens 3y ago
Contrary to all that, I know many people who are now basically immune to power grid issues in the us due to their solar and storage capacity. A friend in Oakland was running off of local storage for 8 days last year while the rest of his block was scrambling to buy generators.
- gorbypark 3y ago
  One of the issues I have with "rooftop solar" is that it's usually sold by and installed by companies who are there to make a quick buck and they don't really explain the details to customers. Besides the predatory pricing and loans, and the blatant lying about payback periods, one big thing is the lack of technical details. The amount of people who don't understand that their new solar install is useless when the grid goes down is astounding.
- elzbardico 3y ago
  Your friend is probably rich or very frugal on his power consumption

cybrox 3y ago

It doesn't make sense if you effectively rent the panels, which means they have to come down again.

anamax 3y ago
Whether or not the panels "have to come down" depends on who pays. If the solar company has to pay, it might not bother at the end of the lease term. This can turn into a very low price to sell the panels at that time.

adrianN 3y ago

It’s nice to have generation close to consumption because you save on transmission infra.

elzbardico 3y ago
No. You don’t. The sun doesn’t shine 24/7.
- adrianN 3y ago
  Demand at night is much lower.

xyzzy123 3y ago

It's a trust issue. People don't trust their utilities, residential solar is (among other things) a hedge. Basically, "how much would you pay to limit how much $powerco can screw you in future?". Human nature means a lot of people will willingly pay double for that.

elzbardico 3y ago
Most people have grid-tie systems. If the power is out, they are down too. Only very rich people have money to buy battery storage enough to be off grid and then this kind of system is not what those companies usually lease. If you’re concerned about blackouts a gas natural generator makes a lot more sense economically speaking
- xyzzy123 3y ago
  This is factually true but my claim is that what motivates people is a desire for greater energy security (EDIT: where improved price stability is one aspect of that, as konschubert points out).
  - konschubert 3y ago
    It also means you're less affected by rising prices. (Not that I expect rising prices, but others do)
robin_reala 3y ago
“People don't trust their utilities” is a strong claim that I assume is very dependent on your location. I think I’ve had maybe two hours total of no electricity in the last five years?
- xyzzy123 3y ago
  Yeah I admit this is pretty situational - the U.S. I don't know much about - but NZ, Australia and most of Europe, consumer sentiment is that we are getting slugged - I don't have a survey to hand but I'm confident I could dig something up (EDIT: e.g: https://www.energymagazine.com.au/energy-survey-reveals-rising-consumer-concerns/ https://www.energymagazine.com.au/energy-survey-reveals-risi...) In the last 5 years, has your kwh price increased? By more or less than inflation? If utility scale solar takes off, do you expect that future prices will reflect a) capital and operating costs plus a fair margin or b) whatever the market will bear?

reacharavindh 3y ago

I’m going to answer your “financially nonsensical” argument from personal situation. I live in the Netherlands. Sure, we have a reliable power grid that doesn’t go offline for hours or any frequently to make a case for grid backup, but the power companies here charge heck of a lot of money for power. Think about it. The utility company commissions a solar farm (lower cost than roof top solar), but surely hire a 3rd company to operate the farm ($), and then the utility company wants to make $ for their shareholders, therefore, we end up paying a lot of € to cover these. Now, I have as manay panels as I could on my roof (10) that generates more than my average use in the Summer. I run a heat pump that can heat & cool and Ioperate it when the sun is shining. I do laundry when the sun is shining. Because of net metering, my grid usage practically cancels out against my solar energy production. When the net metering subsidy goes away, I’ll install a reasonably sized LFP battery at home to smooth out day/night patterns, and possibly covering the occasional cloudy days right after a sunny day. No power costs from April to September already pays the cost of my panels in just 5 years. It is free money(as in I save it from going from my pocket to the utility company and their shareholders). So, it does make sense. Atleast in many parts of the world. If you live in a part of the world with super reliable grid _and_ low prices, or you’re so rich as to not care, then probably, it may not make sense to you :-) I was just talking about it with some friends from South Africa. They said almost every household there sort of needs to be energy independent because the power company is in the ruin. So, solar + batteries it is. What would you do otherwise?

yourusername 3y ago
>Think about it. The utility company commissions a solar farm (lower cost than roof top solar), but surely hire a 3rd company to operate the farm ($), and then the utility company wants to make $ for their shareholders, therefore, we end up paying a lot of € to cover these. You missed the largest reason home solar can be competetive and that is taxes. 11 cents per kWh and 3 cents sustainability charge and then 21% VAT over the cost price + taxes. And then the government mandates the energy companies have to buy your energy for the same price they sell you energy. So as with many thing here it only makes sense because the government has completely distorted the market.
- 3y ago

Kon5ole 3y ago

>Rooftop solar never really made sense in the big picture kind of way. I think it's in the big picture it actually does make sense. True it's not the cheapest, but it is the fastest way to actually get solar panels into sunshine and start solving our problems. The additional cost is paid mostly by "volunteers" instead of having to raise taxes or wait for some corporation to make a move, there is no NIMBY-problem since it's actually the BY-owner who makes the decision. You can mobilize thousands of companies (solar panel installers) at once all around the country. Rooftop solar grows by about the same as a nuclear power plant per year in some countries. Finally the resulting power generation is geographically distributed so that no single rain cloud can cover the entire "power plant". I think larger projects run by governments and large corporations should be focused on generating gas or building battery storage, so that some of that cheap rooftop solar and other renewables can be stored for nighttime and winter, instead of being sold for negative prices at certain times.

alkonaut 3y ago

What's plenty of space? I have perhaps 3-400 sqm of lawn. I'm not going to use 50-100 of that for solar when I have that amount of roof that is otherwise wasted space. I agree that perhaps domestic installations might not be the best idea because you need the same equipment repeated at every home, that could otherwise be centralized at a plant. But for resilience it's pretty neat. If I had more than say one power outage a year lasting more than an hour, I'd definitely be looking at it. I can see why South Africa is a big market (lots of sun, frequent power outage). Perhaps the middle ground between massive scale and domestic scale would be community sized plants serving (say) 100-1000 households.

kragen 3y ago

yes, it's collectively irrational behavior, just like warfare. but it's often individually rational behavior (like defending your country when it's invaded, in some cases) because electric power utilities commonly have monopolies, which causes two problems: 1. they become single points of failure, and their risk tolerance for outages may not match yours, so you may end up either paying excessive costs for reliability you don't need, or experiencing an outage risk you can't tolerate. or they may have outage risks which you can't solve by dumping money on them, such as corruption 2. they sometimes try to extract monopoly rents there are also coordination problems around things like time-of-usage billing. solar power is free during the day, but your utility provider may not be willing to deliver it to you for the extremely low marginal price of transmission and distribution; they may be legally obligated to charge you the same price as at midnight, for example