Solar Power isn't Feasible!

Solar Power isn't Feasible!
This cartoon was on the cover of the book "SolarGas" by David Hoye. It echoes the Sharp Solar slogan "Last time I checked nobody owned the sun!"

Saturday, September 22, 2007

Setting up a home solar electric system: Simplicity itself!

To get started in solar all you need are four basic pieces of equipment:
  1. A Photovoltaic Solar Panel
  2. A Charge Controller
  3. A Battery
  4. An Inverter
This table gives you the basic components of a stand-alone do-it-yourself solar electric power system.

Here are the things you need to buy:
Solar Panel

Rechargeable Battery
Charge Controller


Note: you can get away with just having a solar panel, a charge controller and a battery if you are running DC appliances. However, if you want to run regular AC appliances, an inverter is required (but notice that the Xantrex rechargeable battery depicted above contains IT'S OWN INVERTER). You can also get away without having a charge controller, but you would have to monitor the charge state of your battery to make sure it doesn't overcharge. I have done this by connecting a simple volt meter to the battery and watching it over the day, but you run the risk of ruining your batteries if you aren't vigilant. Our advice is, buy a charge controller and then you can simply leave the whole thing hooked up without worry!)

Hooking the system up is so simple a child can do it (and probably do it better than you!!). It takes the same skills as hooking up a home stereo system -- if you are familiar with connecting speaker wires (red being positive, black negative) to your amp, you already have the know how!

You connect the positive wire coming from the solar panel to the place with the + on it on the charge controller, and the negative wire from the solar panel to the place with the - on it. You then run a positive wire from the charge controller to the + terminal of the battery, and a negative wire from the charge controller to the - terminal of the battery (note, if you are using a "cigarette lighter" type plug, the center is usually positive and the sleeve negative). Then, if you are using regular rechargeable batteries without a built in inverter, you just connect the + terminal of the battery with a wire to the + terminal of the inverter, and the - terminal of the battery to the - terminal of the inverter.

Voila, you are done!

Since you have a charge controller, you don't have to worry about overcharging your batteries. The inverter also shuts down when the battery voltage is too low, so you don't have to worry about draining your batteries. Leave the solar panel in the sun (facing south is best in the northern hemisphere) and keep the rest of the system indoors to protect from moisture (the solar panel can get rained on, so don't worry about that) and you are set.

To get more power and recharge your batteries faster, you can simply add more solar panels IN PARALLEL. That means simply that you run all the positive wires to the same place (the + input on the charge controller) and all the negative wires to the same place. You can add as many solar panels as you like, of whatever shapes and sizes and wattages, as long as you add them in parallel, but you have to make sure you don't exceed the AMPERE RATING of the charge controller. The one shown above is a 7 AMP controller, so it can take up to 7 Amperes of Current.

How do I know how many amps my solar panel puts out?

Most solar panels have the amp rating listed, but a good rule of thumb is to take the wattage of the panel and divide by the voltage, since Volts x Amps = Watts. Most solar panels produce a peak voltage of about 19 volts. Thus, the 15 watt panel shown above is approximately 15/19 = .8 amps. This means that you could hook up 8 of these panels, giving yourself 120 Watts of charging power!

(I should mention here, however, that this would not be cost efficient since the prices of solar panels are highest when you buy the smaller ones -- around $10 a watt! Once you have learned how to set up your own PV system using the components shown above, I recommend you invest in a single 120 Watt panel, costing around $600. The rule of thumb in PV is to try not to pay over 5 bucks a watt, and you can do that by buying the bigger panels.

Hope that helps!

Have a sunshiny day,

T.H. Culhane
Solar Cities
Cairo, Egypt/Essen, Germany/Los Angeles, CA

Wednesday, September 19, 2007

Can't we do better than this? - An editorial

"As Microsoft's Virtual Earth and Google Earth and Second Life battle it out to become the most widely used 3D portals for on-line exploration of virtual worlds linked to real world opportunities, we at Solar Cities can't help but feel a bit embarrassed by the approach that so many people are taking.

A recent Business Week magazine article entitled " Just Ahead: The Web As A Virtual World
Imagine being able to have a digital replica of yourself stroll from one site to another"
epitomizes the problem. The article natters on about how marvelous this technology will be for attending virtual ball games with your chums, getting together with the gals to go shopping in the virtual mall where your avatar (whose dimensions are precisely known) can try on jeans to the approval of your admirers, and other prosaic applications of this powerful technology.

These articles show the mentality of the bored and vain "1st world" consumers who dominate the development and application of life changing technologies. Remember television? It was supposed to revolutionize education. Remember Ford's inexpensive automobiles and his 5 dollar workday? They were supposed to be social levelers, giving everybody access to the American dream.

I'm not going to quibble and say that we haven't seen some of these promises partially realized. Hans Rosling's compelling data visualization presentation at the TED conference does a lot to dispel some of the more dire underdevelopment myths.

But I am ashamed to be part of a priviliged human collective that doesn't express mightier visions when it discusses the potential for good that new technologies can bring. The media needs to inspire us to think further and deeper so that we don't always start out using new technology merely for personal gratification on the most base, prosaic level. I have studied enough micro and macroeconomics to believe that Adam Smith was right when he suggested "the invisible hand" emerging from individual action based on self-interest (I am not one of those people who believes in a Hobbsian outcome, and I don't think self-interest is a "bad"). But I am with those who think that modern economists and their short sighted students ignore Adam Smith's "Theory of Moral Sentiments" to our collective peril. The invisible hand itself needs to be guided by "enlightened self-interest" that comes from a sense of moral responsibility. And this moral resonsibility needs to be modeled.

My point is this: Since we ALL KNOW that people will use new technologies, like on-line virtual reality linked to the real world, to do the prosaic and puerile things like going shopping and seeking sexual gratification and social climbing opportunities and getting cheap thrills, we should be emphasizing the more challenging aspects of the new technologies -- using them to create social and environmental justice and to end the divisiveness and poverty and class separations that drive intolerance and genocide and terrorism.

If the press and our other media outlets created hype around the noblest uses of new technologies, we could expect the public to figure out for themselves all the more banal uses. I was insulted when the best highly paid media writers could do to talk about polymer ion batteries was talk about creating singing and dancing fast food containers, I was insulted when Newsweek reported that despite the fact that climate change will threaten the lives of millions and cause mass extinctions, Global Warming had some upsides, such as our ability to grow wine grapes in northern countries (the party must never stop!), and I am insulted now, when Business Week writers can only point out to us how much fun we can have shopping in a 3D internet.

Look, I am a gamer. And I am an avid shopper. I spend far too much of my discretional income satisfying my anthropoid hunter/gatherer urges and pumping up my troglodyte libido with virtual chest thumping. I know it is fun. And I have seen the possibilities for having even more fun when Google Earth and Virtual Earth and Second Life merge into one ISO standards based free for all of dimension hopping avatars. But come on people, IS THIS THE BEST WE CAN DO?

In my culture it is IMPOLITE to bring up the basic urges and animal-nature things we all take for granted. It is why we don't show people going to the bathroom in the movies and why we don't discuss our sex lives in public. We talk books and ideas and pushing the envelope. We encourage vision and social responsibility. Of course, when we get behind closed doors with our intimates, we do whatever turns us on. The point is, IT GOES WITHOUT SAYING. And I wish that the media and the press would realize that there are things that go without saying when it comes to hyping new technology.

We are facing political, economic and environmental crises of staggering proportions. These are crises that new technologies, particularly data visualizaton and digital earth and improved communications technologies can help solve. I would like to read articles that talk about the higher uses of each innovation humanity comes up with, and leave the cheap talk for the rags on the shelves of the supermarket like the Inquirer. There are people developing exciting Alternate Reality Games with new internet technologies that enable people to "Play their way to solving real problems". I would like to read about how, with a properly designed user interface, it would be entertaining and sexy and smart and fun and exciting to actually do some good for the world.

We can do better!"

-- T.H. Culhane
Co-founder, Solar Cities

Saturday, September 8, 2007

Barium titanate: Better living through chemistry?

Every so often we non-specialists out here in the "general public" get wind of a sea-change possibility that gives us a sniff of fresh hope in the malodorous air that is inexorably filling our hydrocarbon- tainted atmosphere. You have to look hard and keep your eyes peeled, but the hunt pays off from time to time.

For all those of us who really are worried about climate change and the increasing threats of radioactive elements and chemical carcinogens in our environment (and that should be all of us, no?) , the recent announcement of Toronto´s Zenn Motors liscencing EEStor's barium titanate based ultracapacitor technology is one of those payoffs.

A good popular article on the announcement can be found here:

In summary the argument goes like this: The single greatest impediment to the use of renewable energy, which is often intermittent in supply, and to the use of clean electric cars, which need long ranges between fuelings to be accepted by the public, is said to be ENERGY STORAGE.

Ultra-capacitors made from barium titanate can solve that problem and replace batteries. "Punkt", as we say here in Germany.

Dispersed and intermittent energy sources (like the sun, the wind and seasonal micro-hydro) must be accumulated before they can be practically used. Of course, for that matter, so must all energy sources: Practical cars today rely on sunlight that accumulated chemically for millions of years in the form of fossil fuels. So they are really using solar energy. Using oil as their solar energy storage substance, cars have acheived considerable ranges. But although the public would never be willing to wait the eternity necessary to refill their tanks if they had to wait for new oil to form, they still balk at the thought of recharging a battery for a few hours so they can drive to work and back (most of us only drive 60 miles per day on average, which is about what even a home built electric car using standard lead acid batteries will give you on a full charge!).

So, while we will be forced to re-accumulate sunlight once the oil runs out (assuming we are sane enough to avoid the temptation of using the enormous energy accumulated in unstable radioactive metals!) , the relatively slow process of accumulating energy in the chemical bonds of what we call "bio-fuels" and "batteries" will inevitably impede a quick and easy transition to renewable energy supplies in the years before the fossil fuels disappear.

The Zenn Motors announcement augurs a change from all that. They are proposing to use ultra-capacitors instead of batteries. Ultra-capacitors accumulate, store and release energy very quickly. On the order of seconds and minutes rather than hours. You are probably already familiar with capacitors -- they are usually sheets of a conductive metal sandwhiched between sheets of a semi-conductive material like salted paper. Basically they accumulate and store electrons, building up a charge that can become quite powerful. You yourself have probably experienced a few shocking moments as a human capacitor -- every time you rub your feet on a carpet, electrons build up on your skin, and when you touch a metal doorknob -- zap! -- you discharge the electricity you stored with a pop that can be audible and even painful. It is enough to make your hair stand on end -- literally!

Increasingly capacitors have found their way into rechargeable items, replacing short lived batteries. Their beauty is that they hardly wear out at all -- unlike batteries they don´t go dead over time. Since they are basically just surfaces that build up a static charge, they can be used over and over and over again without any change in the substance itself.

Perhaps you have seen rechargeable flashlights like this:

This is the "Mini Shake Flashlight Magnetic Induction Bright LED Rechargeable Flashlight" found in shops all over the world these days (like this one:
We used them at the Wadi Environmental Science Center in Egypt to teach kids about how magnetic induction works because they are clear and you can see through the case to watch the magnet move through the copper coils to create the electricity that lights the LED. But few people stopped to ask "why does the LED stay lit for up to 30 minutes when you are not shaking it if there are no batteries". The secret is, of course, that it contains an internal capacitor that slowly discharges electrons to the LED. Shake it again and you recharge the capacitor. Simple, effective, clean, durable.

There was also an article on the web at one time by a guy who built his own bicycle generator so that he could allow his kids to watch TV without turning into couch potatoes. The idea was that they were allowed to watch TV as long as they could supply the energy for it. So they would get on the bike and pedal and generate electricity for the TV and if they got too tired, they would have to quit. I tried the same technique myself, and bought a 75 watt TV (13 " AC/DC Color TV for campers) that ran on DC power. I hooked up to a bicycle generator I bought from Windstream Power
When I set up my generator I learned that while I was perfectly capable of generating the needed power (a biker can generate up to 150 Watts at full speed for a short while, and can sustain 35 to 75 watts for an hour ; see and ) the problem was that the picture would glow and diminish in brightness just like an old light bulb in a horror movie, depending on how hard I was pedalling. I also learned that you can fry your television if you pedal too fast or too slow -- the thing wants the correct operating voltage!

Obviously something had to be put in between to regulate the voltage. Being ignorant, I went out and bought a heavy deep-cycle rechargeable battery, and a charge controller, just like you would for a typical wind or solar energy system. Then I would pedal to charge the battery and the battery would supply the energy. The battery only lasted a couple of years, and died an early death because I got tired and stopped pedalling and took the temptation to watch a video all the way through using what remained of my battery power. I let the battery discharge, and stupidly, because I was lazy, I didn't get on the bike to fully recharge the battery. I let it sit there discharged for months, thinking "one of these days, when I'm not busy and have more energy, I will get on the bike and recharge the thing." But I never did, and that is how I learned that if you leave lead acid batteries discharge for too long the lead sulfate crystals become irreversible (or something along those lines -- perhaps an expert can post the real mechanism here).

At any rate, I killed the battery by leaving it discharged. It was then that I learned that one can use capacitors in place of batteries, capacitors like the one's sold here:

(I should mention, for the safety fanatics out there, that, as pointed out on the Pedal Power website , if you pedal too fast you can make a capacitor "explode", but then again, you can also cause the acid in a battery to boil out, generating hydrogen which can lead to explosions and... well, there are risks to everything. But since you are only dealing with a 1 Farad capacitor, if you take precautions (and use a voltage regulator) this should not be a worry (just as batteries in a well-ventilated enclosure have never caused me problems! The "Hindenburg" myth has been used by oil addicts for long enough to scare us away from hydrogen power; let us not use "capacitor explosion" fears to make us refrain from using these marvelous devices -- we aren´t talking bombs here!!!! At any rate I doubt many people can pedal that fast and that hard and that long while watching TV.)

This is all besides the point though. The point here is that capacitors are known to be good battery replacements. What the world has been waiting for has been a capacitor large enough, powerful enough and durable enough to replace the batteries in electric cars and in home power systems.

And it appears that thanks to patent number 7,033,406 filed by Austin based EEStor (standing for Electrical Energy Storage, perhaps?) the world won't have to wait much longer. Using Barium Titanate as its medium for high voltage energy storage, EEStor claims the days of big batteries are behind us.

If Zenn Motors is successful in their tests of the barium titanate ultracapacitor, we could see light weight electric cars with the same ranges as fossil fueled cars, and no toxic waste to be recycled or put in the landfill at the end of the car's useful life. And for those of us who are "off the grid", it isn't hard to imagine that we could also use Barium titanate ultra-capacitors for home power, charging them whenever the sun shines and the wind blows and the water flows.

No doubt energy insiders are watching this very closely. Those of you who have seen "Who Killed The Electric Car" will not be surprised if we hear all sorts of "Hindenburgian" scare-monger nonesense about "the danger of exploding ultra-capacitors" or "the danger of getting a lethal electric shock from accidentally touching the capacitor in the wrong way"(anybody who ever serviced CRT screen TV sets or computer monitors will remember the "danger from death by electric shock" warnings on the insides of those devices. We taught students at Jefferson High School in South Central Los Angeles to respect the big capacitors in the monitors when they disassembled them, and then taught them how to use a screwdriver to short them and safely discharge them). Hollywood will doubtless join the oil industry in a campaign against ultracapacitor electric cars because, without a flammable fuel in the gas tank, they won't explode after a car chase. How boring.

But for the rest of us, members of the general public, worried as we should be by global warming, radiation and cancer (to say nothing of terrorist threats), the wonderous barium titanate ultra-capacitor cars are a much awaited example of the better living through chemistry that was promised us after the last world war. Seems it is close at hand with this innovation, and THAT is EXCITING!