Why Don’t We Put Solar on ALL Rooftops?

Summary

This video explores the potential of rooftop solar as an alternative to utility-scale solar farms, addressing environmental and social concerns associated with large-scale clean energy projects. It discusses the technical and geographical potential of solar power, the challenges of implementation, and innovative dual-use solutions like agrivoltaics and floatovoltaics. The script questions whether rooftop solar alone could meet our energy needs while avoiding ecological consequences, highlighting the complexity of balancing land use with renewable energy growth.

Takeaways

• 🌱 The expansion of utility-scale solar and wind parks is causing environmental and social concerns, not just aesthetic issues.
• 🏡 Rooftop solar is considered as an alternative to large-scale solar farms, avoiding some of the legal and ecological challenges.
• 💧 Solar farms can consume significant amounts of water during construction, affecting local water supplies and aquifers.
• 🐾 Construction of solar farms can lead to the displacement of wildlife and destruction of natural habitats.
• 📈 The U.S. is experiencing a grid connection backlog, delaying the implementation of new renewable energy projects.
• 🔄 Rooftop solar can bypass certain obstacles like impact studies and grid connection queues, using existing space.
• 🔆 The potential of rooftop solar is complex to calculate, involving physical, geographic, and technical factors.
• 📊 A study in Seoul's Gangnam district showed that rooftop solar could theoretically cover a significant portion of the city's energy needs.
• 🌐 The actual implementation of solar energy is influenced by a range of factors including costs, policies, and public acceptance.
• 🌾 Innovative approaches like agrivoltaics and solar grazing combine solar energy generation with agriculture for mutual benefits.
• 🌊 Floatovoltaics, or floating solar panels on bodies of water, offer a flexible and space-efficient way to harness solar energy.

Q & A

What is the main challenge of expanding renewable energy capacity according to the script?

The main challenge is the delicate balancing act of land use, which involves not just NIMBYism, but also serious environmental and social concerns.

Why is the expansion of utility-scale solar and wind parks complicated?

The expansion is complicated due to the potential negative impacts on water supplies, construction noise, dust storms, glare, and displacement of wildlife, as well as legal and ecological consequences.

What is the acronym 'NIMBYism' mentioned in the script, and what does it refer to?

NIMBYism stands for 'Not In My Back Yard,' which refers to the opposition from residents to a project in their local area that they perceive as having negative impacts.

What is the potential of rooftop solar in terms of energy generation according to the script?

The script suggests that rooftop solar has a significant potential, but it does not provide a specific figure, as it varies greatly depending on various factors such as location, available rooftop area, and the efficiency of solar panels.

What are the advantages of rooftop solar over utility-scale solar farms as mentioned in the script?

Rooftop solar can avoid legal hassles, ecological consequences, and the need for land acquisition. It also allows for the use of power generated onsite without reliance on transmission lines.

What is the 'interconnection queues' mentioned in the script, and why is it a problem?

The 'interconnection queues' refers to the backlog of renewable energy projects waiting for grid connection in the U.S. It is a problem because it delays the implementation of these projects, causing a bottleneck in the expansion of renewable energy.

What is the significance of the study conducted by Yonsei University researchers mentioned in the script?

The study is significant as it provides a detailed analysis of the physical, geographic, and technical potential of rooftop solar in Seoul's Gangnam district, highlighting the gap between the theoretical potential and the actual electricity generation achievable.

What does the term 'technical potential' refer to in the context of the script?

In the script, 'technical potential' refers to the maximum amount of energy that can be generated by a solar system in a specific environment, without considering market, economic, or policy constraints.

What is the concept of 'agrivoltaics' mentioned in the script, and how does it benefit both agriculture and solar energy generation?

Agrivoltaics is a concept where solar panels are integrated with agricultural practices. It allows for mutual benefits such as protecting crops, reducing water usage, providing shade for animals, and attracting pollinators, while also generating solar energy.

What is 'floatovoltaics' as discussed in the script, and what are its potential applications?

Floatovoltaics refers to solar panels installed on bodies of water, such as lakes or irrigation canals. It allows for the generation of solar energy while utilizing space that does not interfere with land-based activities, like farming or water management.

What is the conclusion of the script regarding the future of solar energy deployment?

The script concludes that dual-use implementation of solar energy, such as agrivoltaics and floatovoltaics, is key to maximizing the potential of solar energy without requiring large-scale land clearance.

Outlines

00:00

🌱 Balancing Renewable Energy and Environmental Impacts

The video script begins by discussing the challenges of expanding renewable energy, particularly solar and wind farms, and the environmental and social concerns associated with their construction. It raises questions about the worthiness of large-scale projects and introduces the idea of rooftop solar as a potential alternative. The speaker, Matt Ferrell, sets the stage for a discussion on the feasibility and benefits of utilizing rooftops for solar energy generation, while also acknowledging the complexities of cost, priorities, and environmental impacts.

05:01

🔍 Exploring Rooftop Solar Potential and Its Limitations

This paragraph delves into the concept of solar energy potential, distinguishing between physical, technical, and realizable potentials. It explains how physical potential is based on solar radiation, while technical potential considers system capabilities and performance. The realizable potential, however, takes into account market, economic, and policy constraints. A study from Yonsei University in Seoul is highlighted, demonstrating the significant but not fully utilizable potential of rooftop solar in the Gangnam district. The summary emphasizes the gap between theoretical and practical solar energy generation and the multifaceted nature of assessing solar viability.

10:03

🌟 Innovative Solar Applications and Dual-Use Implementations

The final paragraph explores innovative applications of solar energy beyond traditional land-based installations. It introduces agrivoltaics, which combines solar energy generation with agriculture, offering mutual benefits to both sectors. The concept of floatovoltaics is also discussed, where solar panels are installed on bodies of water, providing flexibility in solar deployment. The paragraph touches on other niche applications like sound barriers and monuments, and it concludes by emphasizing the importance of dual-use implementations and the abundance of options for integrating solar energy into various aspects of life and infrastructure.

Keywords

💡Renewable Energy

Renewable energy refers to power sources that are replenished naturally and sustainably, such as solar, wind, and hydroelectric power. In the video, renewable energy is the focus as the script discusses the challenges and potential of solar power as a means to grow the world's renewable energy capacity.

💡Land Use

Land use is the management and utilization of land resources for various purposes, including residential, commercial, industrial, agricultural, and environmental conservation. The script addresses the delicate balance required in land use for renewable energy projects, highlighting the environmental and social concerns associated with large-scale solar and wind farms.

💡Utility-Scale Solar

Utility-scale solar refers to large solar power plants that generate electricity for the power grid. The video script mentions the expansion of these solar parks and the associated environmental impacts, such as water usage and wildlife displacement.

💡Rooftop Solar

Rooftop solar involves installing solar panels on the roofs of buildings to generate electricity for local use. The script explores the potential of rooftop solar as an alternative to utility-scale solar farms, discussing its benefits in terms of avoiding land use conflicts and transmission line dependencies.

💡Technical Potential

Technical potential in the context of renewable energy is the maximum amount of energy that can be generated by a technology under ideal conditions, without considering market or policy constraints. The video explains how technical potential is assessed for rooftop solar and the gap between physical potential and what can actually be achieved.

💡Interconnection Queues

Interconnection queues refer to the waiting lists for renewable energy projects to connect to the power grid. The script mentions the backlog in the U.S., illustrating the lengthy process and the significant number of solar projects awaiting connection.

💡Agrivoltaics

Agrivoltaics is the practice of integrating solar panels with agricultural land to create a symbiotic relationship, where solar energy generation complements farming activities. The video script describes how agrivoltaics can protect crops, reduce water usage, and support pollinators, offering a dual-use implementation of solar power.

💡Floatovoltaics

Floatovoltaics involves installing solar panels on floating structures, typically on bodies of water such as reservoirs, lakes, or irrigation canals. The script discusses the flexibility of floatovoltaics as a way to utilize water surfaces for solar energy generation without occupying additional land.

💡NIMBYism

NIMBYism stands for 'Not In My Back Yard,' a phenomenon where local residents oppose the development of projects such as renewable energy facilities in their vicinity due to environmental or aesthetic concerns. The video script touches on NIMBYism as a complication in the deployment of clean energy projects.

💡Community Solar

Community solar refers to solar energy projects that are shared by a community of users, allowing individuals who may not have suitable rooftops for solar panels to participate in solar energy generation. The script cites a study by NREL that discusses the potential benefits and limitations of community solar.

💡IMBYism

IMBYism, or 'In My Back Yard,' is a concept opposite to NIMBYism, where individuals or communities actively support the development of projects like solar panels in their local area. The video script suggests that embracing solar power in one's own backyard could be a key to expanding solar energy adoption.

Highlights

The challenge of balancing land use with the expansion of renewable energy sources, particularly utility-scale solar and wind parks.

The environmental and social concerns that complicate the creation of clean energy projects, beyond just NIMBYism.

The potential of rooftop solar as an alternative to large-scale solar farms, avoiding legal and ecological issues.

The cost barrier as a persistent challenge to the widespread use of solar power.

The impact of solar farms on local water supplies, particularly in areas with limited water resources.

The disturbance to surrounding life from solar farm construction, including noise, dust, glare, and wildlife displacement.

The lengthy process and bureaucracy involved in getting utility-scale solar projects online, including impact studies and interconnection queues.

The advantages of rooftop solar in bypassing many of the obstacles faced by utility-scale projects, such as the need for impact studies and transmission line dependencies.

The difficulty in estimating the potential energy supply from rooftop solar due to numerous variables.

The concept of 'potential' in solar energy, including physical, geographic, and technical potential, and how they differ.

A case study of Seoul's Gangnam district, illustrating the gap between physical and technological potentials of rooftop solar.

The importance of considering the quality of life and public acceptance in the viability of rooftop solar.

The variability of theoretical solar power potential based on different assumptions and estimates.

The idea of agrivoltaics, combining solar generation with farming to create a symbiotic relationship.

The concept of floatovoltaics, using solar panels on bodies of water to generate electricity.

The potential of dual-use solar implementations, such as agrivoltaics and floatovoltaics, as key to efficient solar energy use.

The call for public engagement in discussing and exploring dual-use solar implementations.

Transcripts

Growing the world’s renewable energy capacity  has always been a delicate balancing act,  

and one of the many plates we have to spin  during that act is land use. Utility-scale  

solar and wind parks are rapidly expanding  in size and prevalence all over the world,  

including right in my own backyard. But  it’s not just NIMBYism that complicates  

the creation of clean energy — it’s serious  environmental and social concerns, too. When  

are the negative impacts of siting these massive  projects worth the benefits? When are they not?

With these questions in mind, it’s tempting to  wonder: How much solar power could we squeeze  

just out of rooftops? Could rooftop solar  single-handedly provide us all the energy  

we need while avoiding legal hassles  and ecological consequences? At the  

end of the day…do we have enough space for solar?

I’m Matt Ferrell … welcome to Undecided. 

This video is brought to you by  Surfshark, but more on that later.

We’ve discussed a lot of fascinating possibilities  for increasing and improving solar power on the  

channel from more simple modifications  to the downright fantastical. But if  

you’ve been watching for a while, you might  have noticed a pattern in the tech I cover:  

the most persistent barrier to widespread use  is usually cost (at least, for now). In the  

case of going all-in on rooftop solar, it’s not  so simple. Instead, it’s a matter of priorities.

Let’s step back for a second, though, and talk  about why you’d want to pitch a “cover all the  

roofs!” approach in the first place. Utility-scale  solar is definitely preferable to coal,  

but there’s many more considerations at play than  just aesthetics when breaking new (old) ground.  

For one thing, as they’re being built, solar  farms can soak up a lot of water — thousands  

of acre-feet’s worth. In some areas, that means  these construction projects threaten the water  

supply for locals who rely on aquifers, which are  difficult to monitor and preserve. Unfortunately,  

the same areas that have lots of sunshine to  spare also have limited water resources to live.

Then there’s the other ways surrounding  life is disturbed: construction noise,  

dust storms, glare, and of course, displacement  of wildlife. So, when an undertaking like the  

Aratina Solar Center involves the destruction  of state-protected Joshua trees in California,  

it’s not unreasonable to question whether going  forward with large-scale construction is the  

best decision. And by no means is this the only  solar farm facing opposition from neighboring  

communities and conservationists…trust  me, there's some in my area too.

Even when these proposals successfully clear  the tangles of bureaucracy and public comment,  

it still takes a long time to get them  online. This is especially true in the U.S.,  

which is currently suffering from  a grid connection backlog longer  

than a CVS receipt. Before utilities  can move forward with their plans,  

they need to undergo an impact study. Off they go  into what’s known as the “interconnection queues.”

Over 95% of the projects idling in these  interconnection queues are for renewables,  

with solar representing the vast majority of them.  And by the end of 2023, the combined generation  

capacity of projects waiting for an assessment  amounted to nearly 2.6 Terawatts, which is more  

than double the U.S.’ existing generation  capacity…in total. Not all of these solar  

hopefuls make it to completion — in fact, most  don’t. So yeah, you could say we’re a bit behind.

However, rooftop solar can easily skip over a  lot of these obstacles. While I can tell you from  

personal experience that investing in solar panels  definitely doesn’t spare you from permitting hell,  

it’s not like you have to get in line for  an impact study. You’re taking advantage  

of space you already have to work with  rather than carving out more land. And  

you can use the power you generate onsite, so  you’re not at the mercy of transmission lines.

So, what if we went all-in with rooftop solar? How  

much of our energy supply could  come just from rooftops alone?

Before we try to answer that tricky question,  there’s another piece of tech that isn’t  

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the description below. Thanks to Surfshark and to  all of you for supporting the channel. So, what if  

we went all-in with rooftop solar? How much of our  energy supply could come just from rooftops alone?

Well…I can’t tell you. Not right off the bat,  

anyway. Simply hypothesizing what we  possibly could generate with rooftop  

solar can’t be adequately diluted to a single  statistic, even when you apply limitations,  

like only covering a specific region. There’s  just too many variables to account for,  

so it’s no surprise that researchers have  been trying to answer this question for years.

I can’t give you a meaningful  back-of-the-envelope figure for  

how much rooftop solar has to offer on  a fully realized scale. What I can do,  

is break down how researchers have been  tackling the subject — and that would  

be through various measures of potential.  Even the concept of “potential” itself has  

multiple subtypes in terms of calculating what  we can accomplish with renewables. As a result,  

you end up with different values depending  on what kind of potential you’re looking at.

If you imagine a pyramid of potential,  

like the U.S. National Renewable  Energy Laboratory (NREL) has here…

…then the foundation begins with the physical  constraints of rooftop solar. How much radiation  

is hitting a given rooftop in the first place?  Of course, the total amount of radiation that  

a surface receives currently can’t come anywhere  close to the energy that it ultimately produces,  

and that’s not just because of a  solar panel’s Shockley–Queisser limit.

That brings us to the technical potential of  solar: what is a particular system capable of  

in a particular environment, and how well does it  perform? Here’s the thing: as the NREL defines it,  

technical potential estimates what you can  physically deploy “without regard to market,  

economic, or policy constraints.” In other  words, laying out a technical potential  

figure for rooftop solar doesn’t provide a full  picture. We still have to contend with how costs,  

policies, regulations, and the public  response restrains what it can actually  

do for us in the real world. To PV  or not to PV; that is the question.

For an example of how the differences between  the potential and the possible shake out,  

we can look at a 2016 study published by  researchers from Yonsei University in Seoul,  

Korea. The research team zeroed in on the  capital’s Gangnam district (yes, that one),  

and their analysis followed a three-step  process of determining the area’s physical,  

geographic, and technical potential. Within  this particular study, “physical” refers to  

“total solar radiation on the rooftop,”  “geographical” equates to “available  

rooftop area for solar PV installation,”  and the technical potential is the final  

electricity generation. Here’s a summary  of results, which represent annual values:

Physical potential - 9,287,982 megawatt hours Geographic potential - 4,964,118 square meters 

Technological potential - 1,130,371 megawatt hours

Note that “geographic potential” is expressed  in meters squared, not megawatt hours,  

because it represents the average amount of  rooftop area compatible with solar panels.

So, you can tell right away that there’s a  big gap between the physical and technological  

potentials. As the researchers write, “only  12.17% of the physical potential can be  

generated as electricity.” These results  don’t mean rooftop solar isn’t worth it,  

though. To put that number into perspective,  CEIC Data estimates Seoul’s all-time highest  

use of electricity between January 1997  and May 2018 fell within August 2016,  

the same year as the solar potential study’s  publication. That number was an average of  

4.8 million megawatt hours. Just like that,  rooftop solar in one of Seoul’s 25 districts  

could cover a quarter of the entire  city’s energy needs. That’s impressive.

However, my point is that the study shows  how establishing the suitability of rooftop  

solar is a layered and laborious task,  even for a single region. That’s not  

to mention all the other circumstances  that can make or break the viability of  

rooftop solar…including the quality of life  considerations that drive its acceptance by  

the people it's meant to serve (which we  went over earlier). It’s not just about  

solar’s literal star power. Researchers also  have to take into account factors like this…

Basically, you can’t avoid making assumptions…and  depending on what kinds of assumptions you make,  

your theoretical solar power potential can  vary wildly. That’s how estimates developed  

by one research team can differ from others in  orders of magnitude. You can see how pronounced  

these differences are in this graph from a  review of rooftop solar potential studies.

So, it’s hard enough collecting and refining the  approximations necessary to make an educated guess  

about solar potentials. But no matter how precise  your data is, theoretical plans can’t predict the  

future or anticipate every community, government,  or individual decision. You might discover the  

ultimate solar site…but not have any policy  incentives available to help do something  

with it. NREL pretty much sums it up in a study  about community solar published earlier this year:

“Realistically, the potential accrual of  benefits is a fraction of those high-end  

estimates based on technical potential capacity.”

Where do we go from here? The truth is, weighing  the trade-offs between utility-scale solar farms  

and a widespread rooftop offensive might be  missing the forest for the trees…or maybe  

the sun for the rays. Because so much of solar’s  efficiency is location-dependent, it doesn’t make  

sense to broadly advocate for one over another,  and we don’t have to stop at either. Panels can  

infringe on the ecosystem they’re installed  in, but they can also directly enhance it.

Agrivoltaics, for example, enables  us to create a symbiotic relationship  

between farming food and solar generation.  Panels can protect crops from the elements,  

reduce water usage, provide shade for  animals, and act as hubs for attracting  

pollinators — which happens to be(e) the most  common application of agrivoltaics in the  

U.S. I’ve got a whole deep dive video  on the practice if you’re interested.

There’s also practices like solar grazing,  or letting livestock loose on fields full  

of solar panels and having them go to town. By  partnering with sheep and cows, we can cut down  

both overgrown lawns and maintenance costs as  they take over the otherwise expensive role of  

groundskeeper. If the concept of solar-over-soil  gives you the warm fuzzies, I’ve gone into more  

detail about augmenting agriculture this way  on the channel before, so you know what to do.

Now that we’ve gone over the land, what  about the water? Let me float an idea by you:  

floatovoltaics, or solar panels that catch current  in more ways than one. Any kind of water will do,  

from the open ocean to lakes. But we can get  some of the same flexibility enjoyed by rooftop  

solar by integrating panels into all sorts of  architecture…including irrigation canals and dams.

A while back I took a deep dive into the  flow of canal floatovoltaics projects from  

India to California. Since then, similar  efforts have kicked off in Oregon and  

Utah in the U.S. earlier this year. Just  this summer, the Philippines inaugurated  

its largest PV irrigation system  yet, the first built over a canal.

And if you saw my video on small hydropower,  

you might remember our discussion  of one particular hydro titan:  

the Itaipú Dam along the borders of Brazil and  Paraguay. The dam already provides about 90% of  

Paraguay’s electricity and 15% of Brazil’s. In  a study published in May, consulting firm PSR  

argues that the hydroelectric plant’s existing  installed capacity of 14,000 megawatts could  

be nearly doubled by setting aside just 10% of  its reservoir’s surface area for floating PV.

That’s not to mention the sunny spectrum of  solar niches like sound barriers, balconies,  

billboards, fences, footpaths…heck, even  monuments. By 2025, Amsterdam will allow  

for solar panels on roofs within protected  areas of the city. How’s that for “in my  

backyard”? Should we come up with a new  term? IMBYism, maybe? We just drop the N.

Once you start to examine how social and economic  influences can help or hinder solar’s technical  

potential, it quickly becomes clear that our main  conflict isn’t space. It’s a deceptively simple  

plan to cram as many solar panels onto as many  rooftops as possible. It’s much more difficult  

to assess priorities and anticipate impacts on a  case-by-case basis. But if solar’s massive spike  

in deployment, long-term drop in cost, and overall  technological maturity has amounted to anything,  

it’s that we’re not at all short on options.  So yes, we do have space for solar that doesn’t  

require clear cutting large swaths of land.  Dual use implementation looks like it’s the key.

But what do you think? What dual use solar  implementations pique your interest? Jump into  

the comments and let me know and be sure to listen  to my follow up podcast Still TBD where we’ll keep  

this conversation going. Thanks as always to  my patrons for your continued support and a big  

welcome to Rikki, Mark Loveless, Aaron Addleman,  and Bill Northrup. I’ll see you in the next one.