How Do Solar Panels Work?

iStock
iStock
They’re an increasingly common sight on the tops of buildings and residential properties: sometimes blindingly reflective panels that absorb sunlight and convert it into usable energy. Noted futurist Ray Kurzweil thinks we’ll all be using them by 2028. But how do solar panels work? Your basic understanding of solar panels—that they convert sunlight directly into electricity—is true. It’s called the photoelectric effect, and it was first discovered in the 1800s. Scientists learned that photovoltaic (PV) cells made of selenium were ideal for this purpose. While they later turned to the semi-conductor silicon, the idea remained the same: Up to a third of the energy found in the sun’s rays could, theoretically, be harnessed for electrical power under the most basic setup, and over 40 percent for the more expensive and complicated models. Silicon crystals by themselves aren’t necessarily great for this purpose, though. They need to be altered with boron and phosphorus and layered. The layer of boron-altered silicon has fewer electrons than it needs to form a bond, so an electron “hole” is created. The layer of phosphorus-altered silicon, meanwhile, has too many electrons. The space between is known as the P-N junction. As the sun’s photons enters the PV cells and starts dislodging electrons, the charge attempting to travel through the P-N junction gets diverted to an external circuit that can then carry the power to an inverter. You may not realize that the power generated with this method is a direct current, or DC, the same type found in batteries. To use the energy in a home or building, it needs to be converted to AC, or alternating current, the type found in outlets. And this is the role of the inverter. This kind of green energy has numerous benefits. Electricity doesn’t need to be transported by a utility company to the premises, and excess can be returned right back to the grid. If you’re thinking of installing a system, however, there are some caveats. For one, the upfront cost can be significant—around $10,000 to $13,475, depending on where you live, after tax credits. While you may be able to cut those costs with state rebate incentives or financing, it may take some time to recoup that investment. On the other hand, once installed, solar panels don’t appear to require much maintenance. Without moving parts, they’re not likely to suffer from mechanical issues, although you may need to replace the inverter at some point, which can get expensive. A site like EnergySage.com can also use your specific location to calculate how much a solar panel system might save you. So how do solar panels work? It’s one part the photoelectric effect and one part economy. If Kurzweil is correct, it won’t be long before we’ll all be well-versed in both benefits. Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Amazon's Under-the-Radar Coupon Page Features Deals on Home Goods, Electronics, and Groceries

Stock Catalog, Flickr // CC BY 2.0
Stock Catalog, Flickr // CC BY 2.0

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Now that Prime Day is over, and with Black Friday and Cyber Monday still a few weeks away, online deals may seem harder to come by. And while it can be a hassle to scour the internet for promo codes, buy-one-get-one deals, and flash sales, Amazon actually has an extensive coupon page you might not know about that features deals to look through every day.

As pointed out by People, the coupon page breaks deals down by categories, like electronics, home & kitchen, and groceries (the coupons even work with SNAP benefits). Since most of the deals revolve around the essentials, it's easy to stock up on items like Cottonelle toilet paper, Tide Pods, Cascade dishwasher detergent, and a 50 pack of surgical masks whenever you're running low.

But the low prices don't just stop at necessities. If you’re looking for the best deal on headphones, all you have to do is go to the electronics coupon page and it will bring up a deal on these COWIN E7 PRO noise-canceling headphones, which are now $80, thanks to a $10 coupon you could have missed.

Alternatively, if you are looking for deals on specific brands, you can search for their coupons from the page. So if you've had your eye on the Homall S-Racer gaming chair, you’ll find there's currently a coupon that saves you 5 percent, thanks to a simple search.

To discover all the deals you have been missing out on, head over to the Amazon Coupons page.

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The Reason Supreme Court Justices Wear Black Robes

Judge Thomas Patrick Thornton (left) is sworn in as a federal judge by Judge Arthur F. Lederle (right) on February 15, 1949.
Judge Thomas Patrick Thornton (left) is sworn in as a federal judge by Judge Arthur F. Lederle (right) on February 15, 1949.

Professional attire can go a long way in communicating the level of respect you have for your occupation and the people around you. Lawyers don’t show up for court in shorts and politicians don’t often address crowds in sleeveless T-shirts.

So it stands to reason that the highest court in the country should have a dress code that reflects the gravity of their business, which is why most judges, including judges on the Supreme Court, are almost always bedecked in black robes. Why black?

As Reader's Digest reports, judges donning black robes is a tradition that goes back to judicial proceedings in European countries for centuries prior to the initial sitting of the U.S. Supreme Court in 1790. Despite that, there’s no record of whether the Justices went for a black ensemble. That wasn’t officially recorded until 1792—but the robes weren’t a totally solid color. From 1792 to 1800, the robes were black with red and white accents on the sleeves and in the front.

It is likely that Chief Justice John Marshall, who joined as the fourth chief justice of the Supreme Court in 1801, led the shift to a black robe—most likely because a robe without distinctive markings reinforces the idea that justice is blind. The all-black tradition soon spread to other federal judges.

But according to former Supreme Court Justice Sandra Day O’Connor, there is no written or official policy about the robes, and the Justices are free to source them however they like—typically from the same companies who outfit college graduates and choir singers. It’s certainly possible to break with tradition and arrive on the bench without one, as Justice Hugo Black did in 1969; Chief Justice William Rehnquist once added gold stripes to one of his sleeves. But for the most part, judges opt for basic black—a message that they’re ready to serve the law.

[h/t Reader’s Digest]