How Does Solar Power Work, Anyway?
You've seen the panels. And now you know about solar's incredible potential. Which means you probably have some questions. So let's get to it.
How do solar panels work?
A solar panel "works by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity," according to Live Science. That's a technical way of saying that the panel's photovoltaic cells convert the energy in sunlight to electricity (specifically, direct current (DC)). This DC electricity is then converted to alternating current (AC) by an inverter.
AC is the type of electrical current you typically use when you plug anything into a residential wall socket. If you have solar on your roof, the system's electrical panel sends power to your lights and appliances.
How long will solar panels last?
A long time. Like, a really long time.
Many home array solar panels are guaranteed for decades, thanks to warranties that typically cover 25-30 years. But because their parts do not wear out easily, solar arrays are well-known to continue producing clean electricity even beyond these lengthy timeframes.
"Unlike many other consumer goods, [solar panels] don't 'give up the ghost' at the end of their warranty period and need to be replaced, but continue to still produce clean electricity, although at a slightly less efficiency each year," Clean Technica reported.
"In fact, some decidedly old-school solar cells have been producing electricity daily for about 40 years or so, and are expected to continue to power homes and businesses for decades more."
A June 2012 NREL study investigating the "photovoltaic degradation" rates of about 2,000 solar installations over a period of 40 years found the median solar system lost just 0.5 percent of its efficiency per year. So, by the end of your 25-year warranty, the solar panels on your roof could still be operating at about 88 percent of their original capacity.
Is your '93 Camry still running near-perfect with very, very little maintenance (more on that below)?
(Psst … a quick note on the word "photovoltaic": It means "capable of producing a voltage, usually through photoemission, when exposed to radiant energy, especially light." Which is a very long way of saying "converts sunlight into electricity.")
What sort of maintenance is required?
Not too much, really. Your solar panels themselves can last for decades on end without much upkeep (maybe just remember to keep them free of debris, snow, etc.). But you will likely need to replace the inverter a few times throughout the life of your system.
Like the solar panels themselves, inverters typically come with a warranty—these can range from 5-15 years (and sometimes even longer). Unlike your panels, your inverter will not see its efficiency dwindle very slowly; instead, it may simply stop working and need to be replaced.
However, technological developments on this front are afoot! New "micro-inverters," which are installed or included with each solar panel, are quickly replacing the more-common central inverters that handle the output of all your panels at once. These micro-inverters can have a much longer lifespan (all the way up to 25 years) than a central inverter, and if one does fail, it won't shut your entire system down cold.
Do solar panels work on cloudy, rainy, or cold days?
We'll cut straight to the chase—solar panels work just fine when it's cloudy, rainy, and/or cold.
Are clouds and rain ideal for solar panels? Of course not. They are most effective in direct sunlight. But solar panels can still generate power when the sun is blocked by clouds—more than enough, in fact, to remain a viable source of electricity. Take Germany, for example. It's not particularly warm or sunny, but is nevertheless a world leader in solar energy.
As for winter, there's some even better news: Solar panels are powered by light, not heat, and because of the way the technology works, they're just as effective—if not more effective—in cooler temperatures as in hot ones.
How much does a solar energy system cost?
"In 2018, most U.S. homeowners are paying between $2.71 and $3.57 per watt to install solar, and the average gross cost of solar panels before tax credits is $18,840," EnergySage estimated.
That may seem quite expensive, but it also doesn't take into account the many incentives available to solar customers and the multiple new forms of solar financing that have emerged in recent years that can allow customers to put solar on their rooftops at little or no cost up front.
In addition, in the U.S., a 30 percent federal investment tax credit is available until 2019 (stepping down in the years beyond) and can offset the cost of your investment substantially, and many states also offer their own tax breaks and incentives to encourage home solar panel installation.
And, of course, looking at the straight upfront cost of the system and its installation is far from the whole story, at least as far as your bank account is concerned. Which leads us to our next question …
Can people really save money with solar panels?
Yes. Not only does a solar energy system add substantial value to your home the minute it's up and running, it often pays for itself—and then some!
"Twenty-year electricity savings from solar can be significant, ranging from the low end of $10k to almost $30k," according to EnergySage.
If you follow that math—and please keep in mind your savings will vary, depending on factors like your typical electricity cost, average sunlight in your region, and the scale of your system you install—depending on the final cost of your system after federal, state, and local incentives, in as little as seven-and-a-half years, your system will have paid for itself.
Few major purchases can claim such an impressive return on investment.
Looking at these numbers, the conclusion is clear: Solar isn't just the right choice for the planet—it can also be the smart choice for your wallet. Whatever fossil fuel companies may claim.
The benefits of solar don't end with lower power bills. Cutting carbon pollution? Check. Empowering communities? Check. Creating good jobs? Check and check.
And all that's before we even get to solar's part in transitioning to a clean energy economy and avoiding some of the worst possibilities of climate change. Like increasing extreme weather and the terrible—and terribly expensive—destruction that can come with it.
All Renewables Will Be Cost Competitive With Fossil Fuels by 2020 https://t.co/QectZLGqOF #renewables @350… https://t.co/9rc89HJlCz— EcoWatch (@EcoWatch)1516026187.0
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By Emily Grubert
Natural gas is a versatile fossil fuel that accounts for about a third of U.S. energy use. Although it produces fewer greenhouse gas emissions and other pollutants than coal or oil, natural gas is a major contributor to climate change, an urgent global problem. Reducing emissions from the natural gas system is especially challenging because natural gas is used roughly equally for electricity, heating, and industrial applications.
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What RNG Is and Why it Matters<p>Most equipment that uses energy can only use a single kind of fuel, but the fuel might come from different resources. For example, you can't charge your computer with gasoline, but it can run on electricity generated from coal, natural gas or solar power.</p><p>Natural gas is almost pure methane, <a href="https://www.eia.gov/energyexplained/natural-gas/" target="_blank">currently sourced</a> from raw, fossil natural gas produced from <a href="https://www.eia.gov/energyexplained/natural-gas/where-our-natural-gas-comes-from.php" target="_blank">deposits deep underground</a>. But methane could come from renewable resources, too.</p><p><span></span>Two main methane sources could be used to make RNG. First is <a href="https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks" target="_blank">biogenic methane</a>, produced by bacteria that digest organic materials in manure, landfills and wastewater. Wastewater treatment plants, landfills and dairy farms have captured and used biogenic methane as an energy resource for <a href="http://emilygrubert.org/wp-content/uploads/2019/02/eia_860_2017_map.html" target="_blank">decades</a>, in a form usually called <a href="https://www.eia.gov/energyexplained/biomass/landfill-gas-and-biogas.php" target="_blank">biogas</a>.</p><p>Some biogenic methane is generated naturally when organic materials break down without oxygen. Burning it for energy can be beneficial for the climate if doing so prevents methane from escaping to the atmosphere.</p>
Renewable Isn’t Always Sustainable<p>If RNG could be a renewable replacement for fossil natural gas, why not move ahead? Consumers have shown that they are <a href="https://www.nrel.gov/analysis/green-power.html" target="_blank">willing to buy renewable electricity</a>, so we might expect similar enthusiasm for RNG.</p><p>The key issue is that methane isn't just a fuel – it's also a <a href="https://www.eia.gov/environment/emissions/ghg_report/ghg_overview.php" target="_blank">potent greenhouse gas</a> that contributes to climate change. Any methane that is manufactured intentionally, whether from biogenic or other sources, will contribute to climate change if it enters the atmosphere.</p><p>And <a href="http://doi.org/10.1126/science.aar7204" target="_blank">releases</a> <a href="https://doi.org/10.1016/j.wasman.2019.07.029" target="_blank">will happen</a>, from newly built production systems and <a href="https://theconversation.com/why-methane-emissions-matter-to-climate-change-5-questions-answered-122684" target="_blank">existing, leaky transportation and user infrastructure</a>. For example, the moment you smell gas before the pilot light on a stove lights the ring? That's methane leakage, and it contributes to climate change.</p><p>To be clear, RNG is almost certainly better for the climate than fossil natural gas because byproducts of burning RNG won't contribute to climate change. But doing somewhat better than existing systems is no longer enough to respond to the <a href="https://doi.org/10.1038/nclimate2923" target="_blank">urgency</a> of climate change. The world's <a href="https://www.ipcc.ch/sr15/chapter/spm/" target="_blank">primary international body on climate change</a> suggests we need to decarbonize by 2030 to mitigate the worst effects of climate change.</p>
Scant Climate Benefits<p><a href="https://iopscience.iop.org/article/10.1088/1748-9326/ab9335/meta" target="_blank">My recent research</a> suggests that for a system large enough to displace a lot of fossil natural gas, RNG is probably not as good for the climate as <a href="https://investor.southerncompany.com/information-for-investors/latest-news/latest-news-releases/press-release-details/2020/Southern-Company-Gas-grows-leadership-team-to-focus-on-climate-action-innovation-and-renewable-natural-gas-strategy/default.aspx" target="_blank">is publicly claimed</a>. Although RNG has lower climate impact than its fossil counterpart, likely high demand and methane leakage mean that it probably will contribute to climate change. In contrast, renewable sources such as wind and solar energy do not <a href="https://www.eia.gov/environment/emissions/carbon/" target="_blank">emit climate pollution directly</a>.</p><p>What's more, creating a large RNG system would require building mostly new production infrastructure, since RNG comes from different sources than fossil natural gas. Such investments are both long-term commitments and opportunity costs. They would devote money, political will and infrastructure investments to RNG instead of alternatives that could achieve a zero greenhouse gas emission goal.</p><p>When climate change first <a href="https://www.nytimes.com/1988/06/24/us/global-warming-has-begun-expert-tells-senate.html" target="_blank">broke into the political conversation</a> in the late 1980s, investing in long-lived systems with low but non-zero greenhouse gas emissions was still compatible with aggressive climate goals. Now, zero greenhouse gas emissions is the target, and my research suggests that large deployments of RNG likely won't meet that goal.</p>
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By Charli Shield
When an elephant dies in the wild, it's not uncommon to later find its bones scattered throughout the surrounding landscape.
Elephant Burial Grounds<p>Highly social creatures that form deep familial bonds, elephants have long been observed gathering at the site where a peer or family member has died — often spending hours, even days, quietly investigating the bodies or the bones of other dead elephants.</p><p>Although the popular idea that dying elephants are instinctively drawn to special communal graves — so-called "elephant graveyards" — is a myth, their tendency to go out of their way to visit the bones and tusks of the deceased isn't unlike human rituals at graveyards, says animal psychologist Karen McComb.</p><p>"They spend a lot of time touching and smelling skulls and ivory, placing the soles of their feet gently on top of them, and also lifting them up with their trunks," McComb, who's been studying African elephants for 25 years in Kenya's Amboseli National Park, told DW.</p><p>The most striking part of watching an elephant experience loss, Poole recalls, is the quietude. She still remembers one of the first elephant deaths she witnessed; a mother who birthed a stillborn calf. That elephant stayed with its baby for two days, trying to lift it and defending it from vultures and hyenas.</p><p>"I was so struck by the expression on her face and her body. She looked so dejected. It was really like, 'Oh God, these animals grieve…'. It was just so different," Poole told DW. </p>
Witnessing Emotions in Animals<p>Not all scientists are comfortable concluding that elephants grieve. Among the more than 30 reports of elephant reactions to death that Wittemyer co-reviewed in <a href="https://link.springer.com/article/10.1007/s10329-019-00766-5" target="_blank">a study published in November 2019</a> were accounts of "enormous variation and nuance" he says. "It can be incredibly involved and intricate for extended periods or can be relatively cursory checks."</p><p>In Wittemyer's own experience, it can be difficult not to attribute some kind of emotional experience to the more involved interactions between elephants and their dead.</p><p>He shares the story of an "extraordinary event" involving the death of a 55 year-old matriarch in Kenya in a protected area that happened to be near his place of work. She was visited by multiple unrelated families while she was dying, including another matriarch that exerted such enormous effort attempting to lift her to her feet that she broke her tusk, which Wittemyer says, is "like breaking a tooth." </p><p><span></span>"It was a remarkable example of this heightened emotional state, it was very clearly a very stressful interaction," he says.</p>
A Different Sensory World<p>One factor that limits our ability to fully grasp the way elephants process and respond to loss is our markedly different sensory experiences of the world.</p><p>An elephant's world is fundamentally olfactory — based on smell. Ours is visual. Previous <a href="https://pubmed.ncbi.nlm.nih.gov/25053675/" target="_blank">research</a> has shown elephants possess the most scent receptors of any mammal, and can <a href="https://pubmed.ncbi.nlm.nih.gov/17949977/" target="_blank">use smell</a> to discern the difference between different human tribes from the same local area.</p><p>That could explain why elephants exhibit such interest in sniffing the bones and tusks of others, as a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1617198/" target="_blank">2005 study</a> from McCombs highlighted. When presented with the skulls and ivory of long-dead elephants and those from other large herbivores, including rhino and buffalo, McCombs and her team found elephants approached and were specifically attracted to the remains of their own species. </p><p>Without access to the smells an elephant picks up on, Wittemyer says "an enormous amount of stuff" could be missed by humans when studying these behaviors.</p>
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