7minutesolar

Text of the 7 minute podcast

Welcome to the 7minutesolar podcast.

Hi. I’m Jeff Butler with the second episode in our solar panel primer series. In our first we found out how solar cells turn light into electricity, why they’re black and blue and criss crossed all over, and now we’re going to find out what needs to be done to get that solar power out of the panel and into your house…and beyond. But we’ve only got 7 minutes, so let’s get started.

First an episode 1 recap: When sunlight hits the silicon in a solar cell, some of the energy in the light knocks electrons off some of the atoms, like a cue ball at the begnning of a game of pool. The solar cell gets those electrons organized – sort of marching from one atom to another, and they march along the solar cell through printed wires called bus bars that connect 60 or 70 cells to make up a solar panel. Five or six panels are wired together to make a string of panels – remember that – then those strings are connected to make up the big flat solar array that goes on your roof.

The more sun hitting a cell, the more electrons joining the marching. The parade is called an electric current, and this current moves from the solar cells to the end of the panel towards your house in one direction…a direct current. Commonly called DC

Now about a hundred and thirty years ago Thomas Edison and Nikola Tesla – yes, Tesla – had a big debate about the best way to distribute electricity. Tesla won and since then almost all of the things that use electricity – from lightbulbs to subway trains – have been built using his idea, where the flow doesn’t move in just one direction, it alternates, going back and forth 50 or 60 times a second. It’s called Alternating Current. AC

Yep, AC/DC

Your solar panel puts out DC, but everything works on AC, so you need something to change that direct current to alternating current. That thing is a called a power inverter, and there are two kinds of inverters for home solar systems. Well, two and a half.

The old school and most common one is called a string inverter, because it inverts the electricity from those strings of 5 or 6 solar panels that have been wired together.

String inverters work great if the conditions are great, when the panels get lots of direct sunlight and there aren’t any oak trees or other things casting shade through the day …but there is a drawback.

When an oak tree or something else does throw shade on one of the panels it lowers the power from the whole string. It’s not exactly like this but if you think of that parade idea, even if only a few slow marchers join in a parade, they slow down the entire thing.

So to avoid that, another kind of inverter was developed – a microinverter – micro meaning small. They attach to each individual solar panel, so if panel A is under the oak tree it doesn’t effect the amount of power being inverted from panel B.

The two and a half solution is something in between called an optimizer. It attaches to each panel in the string, but it doesn’t invert the current. It does something called conditioning the DC current from each panel before sending it to a central inverter.

Microinverters are the most efficient – and expensive…string inverters are the least expensive – and efficient – and optimizers are somewhere in between.

But however it gets done, now that the power is inverted to AC you can connect it to the electrical panel in your house.

One problem. Night time. It’s dark, you want to turn on a light. But… no sun, no electrons getting knocked off atoms…no electricity.

The electrons WERE getting knocked off when the sun was shining, but of course you didn’t need your lights on then.

What to do. Well, Before we go further, there’s something to understand about electricity and the marching. Electricity is not PUSHED anywhere, it is PULLED somewhere.

Text of the 7 minute podcast

Welcome to the 7minutesolar podcast.

Hi, I’m Jeff Butler. and this is part 1 of our Solar Panel Primers, in which we keep solar power simple and take it in 7 minute chunks. Today you’ll learn about how solar cells and panels turn sunlight into electricity, the two most popular kinds of panels that perform that electromagnetic trick, how they’re made and why that effects the look, efficiency and price of different panels. But we’ve only got 7minutes, so let’s get started.

75 words MAXIMUM

A solar panel? It’s just a collection of solar cells, those are the things that actually turn light energy into electrical energy.

But one solar cell doesn’t generate much power, you need a bunch of them to do anything useful and since it wouldn’t be practical to put them on a building individually we wire the cells together to collect all the electricity – put a back on it all to keep it rigid, add a front for protection from the weather and TADA! a solar panel. Some people in some places call a solar panel a solar module. But whatever you call it you still can’t do much with one solar panel, so we wire a bunch of THEM together and put them on a roof or the ground and THAT is called a solar array. Cells make solar panels, pnaels make solar arrays.

Let’s get back to the cells because that is where the story begins – well, it actually begins with the sun…

Light is made up of energy packets called photons and when sunshine hits the material in a solar cell those packets transfer their energy by knocking electrons off some of the material’s atoms – like a cue ball hitting other balls in the beginning of a game of pool. The solar cell directs those moving electrons toward other atoms in the material that are looking for electrons, and it gets them to kind of march from atom to atom in an organized way. And when electrons march from atom to atom in an organized way, we call that electricity.

The material that is used in the solar cell is important, because it needs to be something with atoms that can have electrons knocked off easily, but not TOO easily. That kind of material is called a semi-conductor, and it turns out that one of the BEST semi conductors on the planet is actually the second most common element in the earth’s crust and can easily be found…at the beach.

Yep, sand is largely made up of silicon, which in addition to being a great semi conductor, is almost literally dirt cheap and partly why it is used in over 90% of today’s solar cells and panels.

And silicon is one of the reasons for that distinctive solar panel look – those black squares with white dots in between and thin white lines crisscrossing the whole thing. Each of those squares is a solar cell – and here’s why the panels look that way when you put the cells together.

Obviously you can’t use just beach sand for a solar cell, the silicon needs to be purified, so it’s melted in a furnace and then distilled, kind of like making whiskey.

Then it can go to make two different kinds of solar cells. Monocrystalline – mono meaning one – and polycrystalline – poly meaning many crystals.

For mono cells the silicon is melted again, and a tiny seed crystal on a rod is dipped in to the molten silicon, which looks like the stuff the cyborg is made out of in Terminator II.

The rod is slowly turned as it pulled out and the seed crystal literally grows bigger and bigger, making a cylinder – an ingot – about 6 feet – two meters – long and about 6 inches – 15 centimers around. Solid, pure silicon – and all one single crystal.

(Incidentally this is almost exactly the same way computer chips are made out of silicon and why a certain valley in California is named after it.)

You following this, Arnold?

NO PROBLEMO.

Well done!

So then the sides are sawn off the cylinder,

The 2017 Bridgestone World Solar Challenge was the 14th running of a 3,000 km car race across the Australian outback with cars powered by nothing except the rays of the sun.

Teams from Universities around the world participate. In this podcast we visit the University of Toronto Blue Sky Solar Racing Team and their solar car Polaris to find out from Electrical Lead Nick Cusimano and Solar Array Lead (and driver) Nasa Nguyen what it’s like to be pioneers in a transportation revolution.

You have a couple of options for listening. This 14 minute podcast tells the whole story of both building the car at the team’s Toronto workshop and racing it Down Under.

If time is at a premium for you today, the same story is told in two 7 minute podcasts. The first is about the building of the car and can be found »» here. The second is about the racing of Polaris and you can find that one »» here.

However you listen to it, be sure to check out the slideshow and video below. And if you have an opportunity, support the team’s Visionary Sponsors: Barrick Gold, Baumeier Corporation, Magellan Aerospace, AC Waterjet, Celestica, University of Toronto  Havelaar Electric Vehicle Research Centre.

Slideshow: building and racing the Polaris solar car

Video: The Blue Sky workshop and Nasa talks about the solar cells

The 2017 Bridgestone World Solar Challenge was the 14th running of a 3,000 km solar car race across the Australian outback with cars totally powered by the rays of the sun. Teams from Universities around the world participate. In this second episode of a two part podcast we visit the University of Toronto Blue Sky Solar Racing Team and their solar car Polaris.

You can listen to the episodes separately (they are each 7 minutes long) or listen to the combined 14 minute episode. You’ll find the other 7 minute episode »» here and the combined 14 minute episode »» here.

In this episode – Under The Outback Sun – driver (and Solar Array Lead) Nasa Nguyen and Electrical Lead Nick Cusimano talk to us about what is like driving across the continent of Australia in a solar car. They are pitted not only against the environment, but also teams from many of the world’s other top engineering faculties.

In the first episode, Nick and Nasa told us about how the car was put together using purpose-built and customized elements. Everything from the solar cells to the transmission to the intricate electrical switching system are made for solar car racing.

Be sure to check out the slideshow and video below. And if you have an opportunity, support the team’s Visionary Sponsors: Barrick Gold, Baumeier Corporation, Magellan Aerospace, AC Waterjet, Celestica, University of Toronto  Havelaar Electric Vehicle Research Centre.

Slideshow: building and racing the Polaris solar car

Video: The Blue Sky workshop and Nasa talks about the solar cells

Last year was quite the year for solar power, solar panels, electric cars, wind, storage and renewables in general. 7 of the top highlights are covered here, with links to the background stories below.

Keep on shining!

LINKS TO STORIES

98 Gigawatts of global solar capacity installed in 2017

Tesla Australia battery halfway to completion

Tesla battery called on to work a day before official switch-on

Tesla battery sets record in backing up grid

Electric car sales hit a million

Costa Rica runs on renewable energy

Google goes 100% renewable

Silicon cell goes over 26% efficiency

GWU technology could double solar cell efficiency

Solar cell could generate electricity from light AND heat

New record low bid for solar electricity

The 2017 Bridgestone World Solar Challenge is the world’s premier solar race. The 2017 edition was the 14th running of the 3,000 km competition in which solar cars race across the Australian outback  powered by nothing except the rays of the sun.

Teams from universities around the world build their own solar cars and pit them against each oother over the 7 day marathon. This is the first episode of a two part podcast in which we  visit the University of Toronto Blue Sky Solar Racing Team and their solar car Polaris.

Listen the way that fits your schedule

You can listen to the episodes separately (they are each 7 minutes long) or listen to the combined 14 minute episode. You can find the other 7 minute episode »» here and the combined 14 minute episode »» here.

This episode – Putting Polaris Together –  details some of the unique technical aspects of the car and the second gives us a feel of what it was like to participate in the race itself. We find out from Electrical Lead Nick Cusimano and Solar Array Lead (and driver) Nasa Nguyen what it takes to put together the car’s electrical/computer system and rig everything up with solar cells and other mechanical parts purpose-made for the solar car racing community.

In the second episode – Under the Outback Sun – Nick and Nasa give us an idea of what it was like going across the continent of Australia  in this amazing race.

Be sure to check out the slideshow and video below. And if you have an opportunity, support the team’s Visionary Sponsors: Barrick Gold, Baumeier Corporation, Magellan Aerospace, AC Waterjet, Celestica, University of Toronto  Havelaar Electric Vehicle Research Centre.

Slideshow: building and racing the Polaris solar car

Video: The Blue Sky workshop and Nasa talks about the solar cells

This 7 minute podcast with highlights from the pages of 7minutesolar looks at some surprising places where solar power is taking hold. Landfill site, nuclear disaster zones, oil fields, coal mines…and more!

 

Chernobyl to get solar farm as part of plan to rehabilitate disaster zone

Former landfill site to be turned into solar facility with more than 7,800 panels

One of the U.S.’s biggest oil fields just turned to an unexpected power source: Solar

Kentucky coal mine could become a solar farm

World’s largest floating solar farm sits over a former coal mine

China building huge solar farms in the shape of panda

This is the second episode in our 7minutesolar 101 series of podcasts about the basics of solar energy and power.

In this we take seven minutes to give an easily remembered (and we hope entertaining) tutorial on what is the actual definition of a watt, how a watt is a measure of power other than just electricity is, how energy is different from power why we get billed for electricity use in kilowatt HOURS, not kilowatts…and what all of this has to do with eating apples.

In this 7 in 7 podcast we look at some of the latest news and technical breakthroughs in solar panels and solar cells: how a solar panel installation helped a flower grower in Puerto Rico recover from Hurricane Maria, how butterfly wings are improving solar panel efficiency, what that has to do with self driving cars, why greenhouse owners are ‘thinking pink’ and more.

Links to stories referenced in this podcast:

* Solar panels rescues Puerto Rico nursery after hurricane

* Butterfly wings inspire a better way to absorb light in solar panels

* Boost for solar cells also makes self-driving cars safer

* $9 adjustment can make solar panels 17% more efficient

* Charge your phone using ambient light and printed solar cells

* Some plants grow better under magenta coloured transparent solar panels

* Solar power is the fastest growing source of global energy

This is the first episode in our 7 in 7 series: 7 items from the pages  of 7minutesolar.com centred around a specific topic.