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Exploring the “Dark Side” of Solar Power

Challenges remain for an all-renewable energy future, but answers are on the horizon

Covering parking lots with solar panels could produce as much as 40% of the country's current electricity needs. Photo credit: Kevin Dooley / CC BY 2.0 / Flickr

Getting to an all-renewable grid in the U.S. by 2050 is a critical component of achieving the world’s climate goals. Solar energy will be a crucial contributor to that effort. But, there is a “dark side” to solar power and it is increasingly in the news based on a variety of theoretical calculations. The dark side includes the need to trash millions of used, outdated solar panels in landfills. It includes the problem of intermittency, which occurs because solar often produces the most energy when demand is low. And it includes covering tens of thousands of acres of potentially usable land with solar collectors—making the land unusable for housing or agriculture. Let’s look at each of these challenges to the future of solar power and explore some  solutions that shed light on the darkness.

Solar panels and batteries will clog landfills

The International Renewable Energy Agency (IRENA) projects that “large amounts of annual (solar panel) waste are anticipated by the early 2030s” and could reach 78 million tons by the year 2050. It has been projected that with increased efficiency and lower-cost panels, many people will replace their current panels years before the expected 30 years of useful service. Theoretically early replacement could result in 50 times more waste in four years than IRENA predicts. That could result in about 315,000 metric tons of solar panel waste by 2050.

The solution: First of all, most people will not likely rush to replace solar panels before 30 years, when they are still operating at better than 70% of their original production capability. Long term, life cycle assessment (LCA) and recycling must be implemented for solar panels along with all other disposed materials in our economy. The Korea Institute of Energy Research has made great progress on this front. They have developed techniques for recycling 100% of the glass from discarded solar panels and for turning 80% of the other materials into high-efficiency solar cells. They are now licensing this process for commercial use by a solar panel manufacturer.

In the E.U., recycling responsibility is assigned to manufacturers based on their current market share. Producer recycling fees are built into the price of solar panels. It is a realistic hope that improved recycling techniques and strategies will make recycling profitable—thus avoiding the need for government regulation and fees. LCA of batteries, which will be crucial to the success of using solar to meet our climate goals, shows that lithium ion batteries have a significantly lower carbon impact than fossil fuels—and it is coming down. LCA, recycling, and creating a “circular economy” for batteries and solar panels will greatly reduce the need for large-scale mining operations, while reducing or eliminating the need to dump them in landfills.

Intermittency will lower value of solar

Because solar produces energy when the sun shines, it currently contributes little or no energy to the grid during peak hours of energy use in the early morning and evening. This results in the need for natural-gas-fired power plants to fill the gap and may reduce the return on investment on solar farms because they may produce a glut of electricity when it is needed less, resulting in lower pricing. This may stall the growth of the very solar power plants we need to reach the world’s climate goals.

The solution: Batteries for homes, businesses, and utilities are already becoming more cost-effective for meeting short-term peak demand. And a great deal of work is being done to economically produce green hydrogen from excess solar energy to generate electricity during peak demand. The combination of a smart grid, smart homes and buildings, smart appliances, and peak-hour pricing will encourage electric vehicles to be charged, clothes to be laundered, and water to be heated during off-peak hours when energy is abundant. Electric vehicles are being developed with batteries that can function as home and grid storage, allowing for increased battery storage at no or little added cost.

Solar farms displace agriculture and housing

It has been estimated that the average solar farm can produce 357,000 kWh per acre. This estimate will vary depending on factors such as the latitude, cloud cover, and snow cover of the area, along with the power of the collectors themselves and the distance from end use. The U.S. currently uses close to 4,000 billion kWh of electricity per year. To obtain 100% of this electricity from solar would result in covering more than 11 million acres or 17,000 square miles with solar panels—an area larger than many of our smaller states.

The solution: It’s not necessary to locate all solar facilities on land, particularly land that has better uses. There are 8 billion square meters of rooftops in the U.S. suitable for solar—capable of producing 1,400 terawatts of electricity—enough for 40% of U.S. current needs for electricity. There are another 9 billion square meters of parking lots that may be suitable for shading with solar collectors to produce another 40% of our electricity needs. And certain agricultural crops grow well with partial shade provided by solar collectors. Rooftop solar produces energy closer to where it is used, creating less need for long, expensive transmission lines that waste energy.

The efficiency of solar panels is growing, so more electricity is being produced in a smaller area. And contributions to renewable energy from hydro and off-shore wind will further reduce the need for building out solar. Using these approaches, land use will not be a problem.

Going all electric will double the land needed for solar

The above estimates do not take into account the “electrify now” movement and the widespread adoption of electric vehicles, including the car, truck, bus, and public transportation fleets. In addition, green hydrogen will be produced from renewable electricity. According to a Princeton study, if we electrify everything, it is likely our electricity consumption could more than double before 2050. This would require a huge expansion of solar that could take huge swaths of land out of use for housing and agriculture.

The solution: If all new buildings and homes are built to zero-energy or Passive House standards, and existing buildings get well on the path to zero energy, the electric demand from all-electric homes and buildings will be drastically reduced. Rooftop solar collectors will reduce the burden on utility power. New electric vehicles may have solar collectors on their skin, too. And efficiency gains of heat pump HVAC and water heating systems will complement the gains in solar cell efficiency.

Renewable energy powered future is on the way

While there are several serious challenges on the road to a fully renewable energy system, there is a wide array of potential solutions. Thanks to thousands of small technical innovations, the theoretical challenges of shifting to a largely solar-based, all-renewable energy-powered economy are being solved. We can all help speed up the process by creating demand for currently available products that will get us there—solar panels, battery storage, heat pumps, “smart” grid-aware appliances, and electric vehicles, as well as all-electric zero-energy or Passive House homes and buildings. As demand grows, innovation will increase and prices will fall—leading to universal adoption of zero-energy lifestyles. All we need to do is shine our light on the challenges.

Joe Emerson is a co-founder of the Zero Energy Project, where this article  first appeared. It is republished here with permission.


  1. nickdefabrizio | | #1

    Great article. This is a situation that will require numerous solutions, each contributing to the goal. Another big area you did not touch on very much is conservation: becoming more efficient and less wasteful, especially with respect to petroleum and natural gas based products and adopting manufacturing processes that are much more efficient in fuel and material use.

    As for used solar panels with some life left in them, they are relatively light and easy to ship. I know a few rural villages in Africa who would love to have them if they are donated. The US government should facilitate this trade on a wide scale.

    1. capecodhaus | | #2

      I like that thing you mentioned called conservation. That never seems to come first in line as priority. The approach seems to be more like, how efficient can our inefficient behavior become? How much we could conserve if we simply tried collectively would be mind boggling.

      I could see the US Govt sending containers full of used panels to third world countries in the future, and in the back of those containers plenty of room to stash weapons and other contraband for the highest bidder. Free shipping.

      1. nickdefabrizio | | #3

        I will remember the phrase: "how efficient can our inefficient behavior become". I must admit, it is sexier to think about how to build things and design things and cool new gadgets. But sometimes the thing that you do not build or buy is the best of all for the environment. That is one reason why, at 64 yrs old, I have never owned a new car (why should I when there are good used ones around).

        I am going to hope your cynicism about shipping weapons is unfounded, but history does suggest it is not uncalled for, sadly....One of the reasons why I work with and sometimes in Central Africa is that America seems to have abandoned it and yet so much of the future of our planet and humanity hinges on whether this area and the people who live there can flourish in a fair and sustainable way. Hopefully in the future we can build good relations based on something other than military considerations.

      2. charlie_sullivan | | #4

        You prompted me to estimate some numbers. About 300 million solar modules in operation in the US, and about 400 million guns is possession of civilians. Growth rates are about 60 milllion/year and 18 million/year respectively.

      3. GBA Editor
        Kiley Jacques | | #22


        I really value your point: ". . . how efficient can our inefficient behavior become? How much we could conserve if we simply tried collectively . . ." It puts me in mind of the book I am reading by Lloyd Alter, "Living the 1.5 Degree Lifestyle," which you can get a glimpse of here. Lloyd's message, in essence, is that we are collectively responsible for taking climate action on an individual level, and that the emphasis should be on sufficiency, not efficiency, i.e. learning to live with less--not making our inefficient behaviors more efficient. That's my motto too.

  2. jason_v | | #5

    "the worlds climate goals", minus China, India and every developing nation you mean.

  3. jason_v | | #6

    Your conjecture that people will responsible use old solar panels is a fantasy.

    1. nickdefabrizio | | #8

      No, the problem is not with panels, it is with batteries, and these issues can be addressed. Also, this is primarily an issue in large cities that have many electronic devices; not in the rural villages where I work and where very little is wasted. Just the ability to run a few computers or smart tablets in the local schools-connected to the existing 3G network -can make a huge difference to kids and their ability to learn about a world that is encroaching on their villages but has not bestowed upon them enough resources.

      1. tillalb | | #9

        Thank you for not being cynical, and for being patient with those who may not be as wise. Much easier to be cynical than trying to be helpful, because helpful people are vulnerable to disappointment.

        To your point: of course people in poor countries will readily use outdated technology, as they have always done, and this could certainly work for old solar panels if it can work for old cars/cell phones etc.

        1. capecodhaus | | #10

          The Third world will always accept used items. As good as that seems it really just underlines the fact we live on a planet that is controlled by few people, without equity for all and consumption is king.

          Imagine a planet where there wasn't First or Third worlds. A planet not based on conspicuous consumption, without a tiered system of entitlement and control, where all people had equity and purpose in it.

          Mimicking First world behavior is not the answer to a sustainable future on this planet. Eight billion people are trying to join its ranks daily and its not working. We need fundamental shift.

          1. tillalb | | #11

            Using old solar panels is not “mimicking first world behavior”. Would I rather live in utopia? Absolutely. Since that’s not an option, let’s try to live in a reasonably earth friendly way. If you are trying to make the world more equitable, like the OP, great. I just don’t get why anyone has a problem with his suggestions of getting old Solar panels to poor countries instead of throwing them away.

          2. nickdefabrizio | | #13

            Actually my experience is that people who live in places with few resources are often pretty good stewards of the environment and resources they have IF they are given a reasonable opportunity to choose a good path and are not forced by external pressures to choose the wrong path. They are actually more likely to do a better job than westerners. A good example of the foregoing is the organization I support in Central Africa often hires poachers to help cook and distribute food to the nursery schools we built and we also offer other jobs to these men, in part because that keeps them away from poaching and in part because they are often very skilled people who are glad to abandon poaching for more productive and sustainable livelihoods. They know more than anyone that poaching is not sustainable as the animals disappear. Just giving them a chance for an alternative occupation is a great way to help the environment and the kids in the village at the same time..

    1. doug_horgan | | #20

      Agreed generally's complicated, expensive, and currently in active use as a greenwashing strategy, by people who depend on piping flammable gas around...but it's possible it would have a place as a way to store energy created by cheap solar.

  4. user-7688527 | | #12

    Wow, no wonder we can't figure out the way forward. The conversation goes from trying to save the planet through sustainable energy and conservation to smuggling arms on container ships. If we could harness some of this negative energy we could power nothing.
    Informative article about the potential issues with panels that have become depleted. This issue, although important, is easier solved than the consequences of burning fossil fuels.

    1. nickdefabrizio | | #14

      Here is some positive energy. This is the health center we financed in Banda Village Rwanda. 2 hours from the nearest paved road- in a village with no electricity except a few solar panels. All done by hand. Look at how nice the construction work is. by local craftsmen...very high quality with concrete made with low levels of portland (although freeze thaw cycles are not an issue) and planks sawn by hand from local (though not indigenous) eucalyptus trees

      1. Expert Member
        MALCOLM TAYLOR | | #15


        Well done!

        1. nickdefabrizio | | #16

          Thanks!..... but we just supply the money-the local villagers supply the hard work and skill. Here is a pic of a sawyer cutting hardwood logs into lumber the old fashion way-I think I mentioned this on a previous thread

      2. ktim | | #23

        That's beautiful!

    2. Deleted | | #18


    3. Deleted | | #19


  5. user-6846716 | | #17

    Do you have an editor? Why in the heck aren't you keeping a common math reference? first its acres, then its square meters, kilowatt, terawatts C'mon man, that is pathetic. KISS!!!

    1. doug_horgan | | #21

      I agree it would have been better if the square area numbers were in the same units!
      FWIW, the article says 11 million acres of solar panels would be needed. The later reference to 8 billion square meters of roofs and 9 billion square meters of parking lots, add up to about 4 million acres together. If i did the math right.

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