Hello Reddit! We recently authored a report on the rise of solar power in the United States and we thought you might be interested. We both work for the Union of Concerned Scientists, and we’re interested in all things solar—benefits, challenges, and opportunities. Ask us anything!

John Rogers is a senior energy analyst at UCS, with degrees from University of Michigan and Princeton and an entrepreneurial past (including cofounding a solar company in the 1990s). His passions extend to energy efficiency (especially LEDs!) and energy/water conflicts.

Laura Wisland is also a senior energy analyst at UCS and an expert on California renewable energy policies. She holds a master’s degree from UC Berkeley, and focuses on providing technical analysis to legislative and regulatory agencies.

Since there are two of us, we've enlisted a helper to collate our answers, but we’ll leave our names so you know who’s talking. We’ll start answering questions around 3 pm EDT (7pm GMT). Ask away!

Proof, more proof

Edit: Thanks everyone, that was fun! We're done now but hopefully will be on Reddit more in the future. Cheers!

Comments: 121 • Responses: 22  • Date: 

adub8877 karma

What is the number one cause of people not embracing solar?

ConcernedScientists9 karma

Funny, I was just trying to figure out the reasons why I hadn’t gone solar yet. There are a few: sun/shade (do I have enough of the one and not too much of the other?), orientation (my roof doesn’t face south), and, of course, cost. But for each of those, it’s pretty easy to push back on myself: I really haven’t gotten that part of the roof assessed, even though it’s not a hard thing to do. My west-southwest-facing roof actually has some advantages, at least in terms of the electricity system as a whole (more generation later in the day). And the costs (as we’ll talk about shortly) have dropped an amazing amount just over the last 4-5 years, plus there are all kinds of leasing options.

So I’d say the biggest factor for a lot of people is inertia: people don’t have solar because they don’t have solar. In the big picture, overcoming that requires more public education about solar’s costs and benefits. It also requires more pioneers; studies show that if your neighbor gets solar, you’re much more likely to get it yourself.

So thanks, pioneers.


nosynarwhal4 karma

The per watt cost of a photovoltaic in USA ($5/W for residential according to Wikipedia) seems highest of any nation in the world. Why is it so expensive to install photovoltaics in the US? Even the Germans seem to pay less than half of what we do for a solar cell. What exactly are we doing wrong?

ConcernedScientists3 karma

Great question. Wikipedia’s behind the times though -- this is a really fast-moving game. The latest stats show household PV at under $4 per watt, meaning a 5-kilowatt system will run you less than $20,000, before the 30% federal tax credit and state and local incentives (which can bring you below $10,000).

But you’re right: Solar in Germany, the world leader, still costs half as much. That has mostly to do with the “soft” costs, stuff like sales and permitting (and profits). Part of that is just a scale issue: more installations in a given area can mean lower per-system transaction costs. In that sense, we’re doing things right, or at least right-er, by scaling up so quickly.

And it’s a virtuous cycle, as more solar makes solar cheaper which means more solar. -John

freeBrunch3 karma

What can we learn from Europe's (specifically Germany) utilization and experience with solar power?

ConcernedScientists3 karma

I think one of the biggest lessons we have learned from Germany is that you don’t have to be an extremely sunny locale to go big on solar. Germany has more installed solar per capita than anywhere else in the world, and it’s not exactly known for its tropical weather. Germany proves to use that electricity grids can handle much higher levels of solar than we see here today in the U.S.

Germany also proves that the more simple and streamlined we can make the contracting and installation of solar, the better. Germany used a feed-in-tariff, which is basically a standard contract for a fixed price. This approach greatly reduces the time and money used to negotiate contracts, and things can move quickly. Some people would disagree that fixing the price of solar does not make sense because it has been changing so dramatically over time, but they definitely got something right by making the process simple.

Also, scale matters. Germans are paying less for solar today because they have been able to reduce the “soft costs” associated with things like sales, permitting, marketing, and labor. The US is making strides in this area too. California just enacted a law that requires local governments to adopt a solar ordinance by September 30, 2015 that will streamline permitting process for small residential rooftop solar systems. -Laura

nosynarwhal3 karma

Have we achieved grid parity in the US for solar power? Sans any subsidy does it make sense to generate solar power or buy from the grid? Or if that's too vague, in what cities / states would you say it is currently cheaper to generate than buy from grid?

ConcernedScientists1 karma

Parts of the U.S. have indeed achieved grid parity (that is, your rooftop solar can produce electricity as cheaply as you can buy it from your utility) and indications are that a lot more places are going to

Whether you’re there or when you’re going to get there depends on a lot of factors: how cheap your local electricity is, for example, how vibrant your solar supplier options are (competition, economies of scale), how cheaply you can borrow money to buy a system, and of course how much sun you get (though there’s less variation in that than you might think).

It can also depend on how you use electricity at home, and how you get charged for it. If you have time-of-use metering, meaning you pay a higher price for electricity at peak times and a lower price at low-demand times, solar might serve you well, since peak times have typically been during the day in many places.

For a sense of where grid parity stands, there’s a map we put together, but also links to DeutscheBank and NRG on the issue, here: http://blog.ucsusa.org/how-much-does-rooftop-solar-power-cost-grid-parity-633 -John

agilla1 karma

Sorry if this is a stupid question, but is this map just a function of relative prices?

Edit: a stupid questions

ConcernedScientists2 karma

Sorry that I wasn’t clear: it’s a function of a few things, notably local prices for electricity and amount of sun. A more sophisticated analysis (we put all the caveats in the methodology) would also take into account local/state incentives. We were building on some good work by NREL (the National Renewable Energy Laboratory) in doing that analysis. Their work also included a price on carbon, but we took it out (for now…).


AllahAkbork3 karma

Could you see solar power become a large energy supplier in the US, or any other nation? As of my knowledge there are cheaper and more effective energy sources such as Wind or Hydroelectric. I would love to see more solar panels in lots of places, especially because of the close proximity to electric access in areas far from electricity.

ConcernedScientists2 karma

Totally! And you’re right: the potential for proximity is virtually unbeatable.

The recent cost improvements have been amazing to watch, and the market has really responded. Just considering residential solar, we’ve gone from around 30,000 houses having solar to close to 500,000 now, and we’re headed for maybe 1 million to 3.8 million by 2020 (depending on what projections you use). And residential is just one piece of the solar picture.

UCS’s own modeling tends to show wind as the dominant renewable energy source, because of how well it scales up, and its current cost advantage (and because of the unlikelihood of more large hydro in the U.S.). But that ranking depends in part on how much progress solar continues to make. All my years of working in solar didn’t prepare me for the incredible progress that the last few years have brought, so my crystal ball may be a little… sunstruck, I guess.

A great resource for envisioning a solar-drenched future is the Department of Energy’s SunShot initiative. It’s pushing hard to get solar costs down to around 6 cents, to then get solar to the point of supplying maybe 14% by 2030 and 27% by 2050. - John

GarlicAftershave3 karma

1.) A decade previous, an engineer observed that the amount of power supplied by a standard solar cell over its lifetime was less than the amount of work required to manufacture and distribute that cell. How do things stand now, with regard to the large cells we see today?

2.) Looking even further back, in the late 1970s there was a contention in the press that American solar firms were being bought up (and presumably shut down) by petro companies, presumably on the basis that they didn't want the competition. Was this a thing that happened/happens or just hippie conspiracy theorism?

ConcernedScientists1 karma

1) Don’t believe everything engineers tell you (says the engineer...).

The energy payback period depends on both the panel (technology and manufacturing processes, for example) and the use (how sunny the location is, for example). In general, though, solar panels (PV modules) pay back their embedded energy in one to four years, according to the National Renewable Energy Laboratory.

2) Conspiracy theories can be fun, but I don’t really see one here. A lot of oil/gas companies tried renewables in the 70’s and 80’s, and couldn’t crack that nut. Exxon got out in 1986, I think, and ARCO and Mobil in the early 90’s. But others have persisted, or gotten back into it. If there’s money to be made in it, they have reason to embrace it. There’s a huge market.

There are, though, other ways that oil/gas companies have undermined efforts to move toward solar and other renewables -- funding contrarian groups to undermine understanding of climate science or renewable energy specifically. There are lots of resources out there on that (go to the UCS website or our blog and search for “Koch”, for example). -John

MrArakis3 karma

What is the useful life of a solar panel? One typically used for a single family dwelling?

ConcernedScientists1 karma

Warranties these days are often 20 to 25 years, meaning the panel is guaranteed to keep producing at a certain level (80-90%, say) during that period.


nosynarwhal1 karma

20 to 25 years might be longer than the expected life of these companies. As a practical matter, what happens if they go bust? Is there a warranty insurer on top? Is accelerated testing a reliable way to extrapolate to 25 years? Won't a lot of ROI calculations go bust if they happen to last 15 years instead of 20?

ConcernedScientists1 karma

I haven’t been directly involved in that part of the business, but I believe that a company would have to pay into a guarantee fund or buy a related insurance policy. And yes, accelerated testing is what they do, I expect using IEC protocols, which presumably have themselves been field tested over the decades.

You’re right that module life would affect return, though panels are a much smaller piece of overall system costs than in, say, Germany. (That’s the upside, I suppose, of having higher soft costs; see the related question.) The latest Lawrence Berkeley National Lab solar update (link below) has a great graphic showing how small the panel piece really is (link below to the report, and to the graphic itself). http://emp.lbl.gov/publications/tracking-sun-vii-historical-summary-installed-price-photovoltaics-united-states-1998-20; http://blog.ucsusa.org/wp-content/uploads/2014/10/LBNL-PV-system-cost-module-and-more.jpg

So module life matters, but much less than it used to. -John

MrArakis2 karma

I have read that Solar Farms pose a threat to birds. What can be done to mitigate or eliminate injury or death to our avian population?

ConcernedScientists3 karma

I’m not aware of any threats that PV projects (large or small) pose to birds, so I am assuming you are talking about the challenges that a large-scale concentrated solar power (CSP) power tower is facing in California. The issue is that the project uses large mirrors to direct sunlight onto a boiler atop a tower to create steam, and insects and avian species have been singed by the concentrated beams of light and heat.

There’s no question that when you build a large power plant–coal, gas, renewable–the things already living there will likely be impacted, and the uncertainty about what this development actually means for critters on the ground is compounded by the fact that this is a new technology. Site specific data collection to fully understand what lives in the area (or might migrate through) before projects are built is critical. It’s also important for the solar developers to connect with locals in the area, to gather information and build trust. This results in the most transparent and high-quality flow of information. The American Wind Wildlife Institute is a good model for actions like this. - Laura

SSJStarwind162 karma

How do you feel about Elon Musk entering the Solar power game?

ConcernedScientists6 karma

I say bring on the visionaries that will help jumpstart new clean tech markets. Elon Musk’s leadership at SolarCity has helped it to become one of the largest rooftop PV installation companies in the country. I am sure you’re also aware of Tesla’s new initiative, the “Gigafactory”, to produce lithium-ion batteries for at least 500,000 electric cars by 2020 (this number is equivalent to more than all of the lithium-ion batteries produced worldwide in 2012!). Production at this scale will provide a needed boost to the market and help lower costs.


trigunned2 karma

Have you considered creating a comic book about this dude, who gets his powers from the sun? Could help raise awareness :D

ConcernedScientists6 karma

I’m with you. Though it may already have been done. I have tacked to my office wall Issue No. 1 (bet you’re jealous) of Solar Lord, a gift from my brother from when I worked in solar. I’ll admit, though, that it’s been a few years since I’ve read it, so I can’t actually remember how the sol-to-human power transfer worked. -John

Edit: Photo proof

agilla2 karma

Do you see solar being adopted any time soon at the utility level? Are there economies of scale in solar installations that there are significant benefits in "going big" or is solar maximally efficient at the household level?

ConcernedScientists3 karma

Definitely yes and yes (and yes/no):

  • Large-scale solar is now more than half of the U.S. solar market, even if you consider just PV (that is, not CSP, which is all large-scale).

  • Why is that? You guessed it: cost. The most recent figures for electricity costs (levelized cost of energy, or LCOE) show “utility scale” at ½ to ⅓ the cost of residential.

  • But you’re also right on when you bring up the point about efficiency. Large-scale solar has economies of scale, so efficiencies that come with that. But residential solar is placed right where the electricity is going to be used, meaning that you’re not losing energy in transmission (line losses for larger remote power plants -- solar or other -- can add up to 5-8% of the electricity, lost as heat while the power is being moved to where it’s needed). -John

secondarycontrol2 karma

Are we at the point now where it would be wise, economically, to enter into a long-term agreement to buy solar power at a given fixed rate (ie solarcity), or do you foresee future advances that would/could significantly drive the cost of solar down--and make one regret entering into a long-term rate agreement?

Edit to add- obviously the tech will improve over time. But I'm wondering how much and how fast. I mean, as an example, to enter into a 20 contract at a fixed rate, when the price/kWh may 1/2 in 5 years might be foolish. 10 years? Maybe. 15 years? Then one might as well do it now.

ConcernedScientists2 karma

The ability to fix your electricity costs has huge benefits because you have a stable and predictable electricity bill over the year. That’s a benefit you get from investing in solar TODAY. It’s true that solar prices have come down dramatically in the past few years, but I don’t think that waiting for them to drop lower is a good reason to postpone the investment. Similar to investments like computers or TVs, prices will change over time as the technologies improve. I think it depends on what type of buyer you are, and how much research you have to do before you feel comfortable making the investment. The Lawrence Berkeley National Lab releases an annual report on solar costs, so this might be something for you to check out. Here’s the one from 2013: http://emp.lbl.gov/sites/all/files/lbnl-6350e.pdf

They track the falling cost trends and make the point that “soft” costs associated with PV installations (like permitting, marketing, mounting hardware) are areas where solar costs can decline further over time.


drunkinbed2 karma

Why does there seem to be such a huge challenge with developing a sustainable method for storing solar energy? Are there any companies that you feel are on the brink of producing a scalable solar energy storing device?


ConcernedScientists2 karma

We have figured out ways to store electricity, the problem is that they are not as cheap as they need to be in order to make them a large and cost-effective player on our electricity grid. There is a lot of exciting research and analysis happening now to determine which types of storage (pumped hydro, batteries, flywheels, etc…) will be most useful to the grid, and that information is critical because it will help send clearer signals to developers and innovators bringing products to market with the highest value.

In addition, we need scale to bring prices down. Tesla’s “Gigafactory”, which intends to manufacture lithium-ion batteries for at least 500,000 electric cars by 2020, is one promising example of an attempt to find that scale and bring prices down. -Laura

Horforia1 karma

How can I get a job working with solar energy? I'm retiring from the us army soon, and I've always been interested in renewable energy.

ConcernedScientists1 karma

Have you checked out the Solar Energy Industries Association’s website? They have a pretty comprehensive list of job opportunities: http://www.seia.org/solar-jobs


powergauge1 karma

How did you discover your passion for solar power?

ConcernedScientists1 karma

It sorta snuck up on me. I had some early fascination with solar, but then went off to do other things. But when I was working in Latin America, a solar pioneer showed me the light, as it were -- helped me understand the potential of small solar systems to serve unelectrified rural areas of developing countries. This was when markets like those were much more a focus of the U.S./global solar industry. I ran with that for years, including helping that pioneer found companies to do that great work.

UCS has given me a chance to be involved with lots of other energy technologies and issues since, but solar will always have a central place in my heart. And maybe, we can hope, on my roof.


billdietrich11 karma

Why is it that a home sell-back-to-grid installation apparently requires expensive interface hardware, while the power utility can install individual solar panels on top of telephone poles without similar expensive gear for each panel ?

ConcernedScientists1 karma

I hadn’t really thought of that, even though I admire all the panels I pass on the highway. If it’s truly for telephone service, that operates at a much lower voltage, so they could be just configured to charge batteries. But I’m just guessing.

As for the interface hardware, that has to do with converting the output from the solar panels (direct current, or DC) to what our houses and the electricity grid want (alternating current, or AC). But that piece has changed a lot in recent years, with some panels now having their own inverters (one per panel), instead of having one central one for the house. Each approach has advantages, of course, depending on local circumstances. -John

kwseattle1 karma

With the drop in costs for PV, it seems that large CSP projects may no longer be developed much. Do you agree? What could CSP offer than PV does not? Are the storage options more developed with CSP?

ConcernedScientists2 karma

I agree that PV is being developed faster and at a larger scale than CSP these days., There are several reasons for this. The main components of CSP projects—steel and mirrors—have not experienced the dramatic cost declines that solar panels have. And, because CSP plants require very strong solar resources, they are more limited in terms of where they can be built.

But one advantage CSP has over PV and many other renewables is its ability to store the heat from the sun in molten salts, and generate electricity later. This storage lets CSP systems extend the “shoulder hours” of their generation patterns and generate electricity a few hours before the sun rises and a few hours after it sets, making it easier to integrate electricity from such plants into the grid. Even without storing the salts, since CSP systems generate electricity using very high temperatures, momentary cloud cover does not lead to the same minute-by-minute variation in electricity production that PV systems experience. These two characteristics are valuable to the grid, and big benefits of investing in some CSP. -Laura

drake07271 karma

Last time I seriously looked at solar for my home, there were two methods of storing the energy. One was basically direct feed into the home network and storing solar power in some type of conductor or battery. The second one is to tap into the existing grid and cutting a deal with the electric company. The second option seems the most appealing, since you put power back into the grid, and can pull power on shady days. Are there any new options out there, or are we still stuck with these two options?

ConcernedScientists2 karma

Going completely off-grid with solar PV and onsite battery storage, or still being connected to the grid and relying on it when the sun’s not out are still the two main options out there for folks that want to go solar.

But, there are some very new and cool “shared solar” opportunities that people who can’t go solar on their own (e.g. shady rooftop, they live in an apartment building and don’t own their roof) can check out. These “virtual” net metering programs allow electricity customers to subscribe to electricity generated from a larger off-site solar system—or even own it outright—and apply the solar generation as a credit on their electricity bills. This type of arrangement is also called “community solar” or “solar gardens.” At least 11 states have some sort of shared solar program now. The Interstate Renewable Energy Council is a great source of information if you want to learn more about shared solar models. -Laura

senor_blake1 karma

I'm not sure how much you guys know state wise, but Alabama power has been painfully slow at adopting alternative power. What causes this and wouldn't it help in the long run if they focused sails on solar power?

ConcernedScientists2 karma

I think so! But that’s because I am extremely worried about global warming, and what’s going to happen to our planet and our public health if we keep spewing fossil fuels into the air.

I don’t have any direct experience with Alabama Power, but I’d suspect they would say they have coal and gas assets that their ratepayers have already paid off or are in the process of paying off, and that it costs too much to make the switch to solar.

My response is that the true costs of burning dirty, unsafe sources of power are not fully reflected in the generation prices. We pay tangible, quantifiable costs to our public health and the environment to mine, transport, and burn fossil fuels. And, unlike fossil fuels, which will run out some day and get a lot more expensive as supplies decrease, once a renewable energy plant like solar is built, the cost of the fuel IS FREE AND WILL NEVER RUN OUT.

So, it’s a matter of perspective. It’s not surprising that change inside a utility is slow, but these changes absolutely need to happen and utilities like Alabama Power need to get on board and figure out how to make renewable energy work for them. -Laura

BoogLife1 karma

What would be your recommendation for a homeowner looking to purchase solar panels for their home? Nothing crazy, just something to start with that one could add to in the future.

ConcernedScientists1 karma

Fine question (and something I’ve been thinking about myself). A few ideas:

  • Talk with friends and neighbors who have gotten solar.

  • See what sort of directory/listings you can find from your local/regional solar or renewable energy organization, like NESEA (the Northeast Sustainable Energy Association), or the national American Solar Energy Society (ASES).

  • Go on a local solar home tour, if you’ve got one: www.nesea.org/gboh/

  • Google “go solar” -- various websites that can help you find options. Ex: http://cleantechnica.com/2013/02/02/how-to-go-solar/

As for adding in the future: The microinverters I talked about above may make it easier to start smaller and add as you can. You may want to go ahead and have the mounting hardware in place for the larger system, just to save money later. And you’d want to consider the 30% federal tax credit; I don’t know how that works if you do multiple purchases.

Depending on where you live, you may also be able to buy into a larger system -- “community” or “shared” solar. The idea is to count the output from a larger (and therefore potentially cheaper system) against your own electricity bill, if you live in a place with “neighborhood” or “virtual” net-metering. And if your area doesn’t have it, feel free to call up your elected officials and tell ‘em you want it, and now. -John