Archive for July, 2008

Link: “How I built my Solar Panel”

How I built my solar panel

The link above demonstrates a nice DIY version of a solar array, using damaged solar modules that can be bought at low price on eBay. This resourceful astronomer also built himself a DIY wind turbine, so if you’re considering doing either, this is worth a look.

This panel was designed to work in sunny Arizona (a beautiful state!), which is a perfect place for setting up an array, especially given the large number of off-grid properties there which would be prohibitively expensive to wire up to the utility power company.

He includes lots of good tips about what to look for when buying your solar panel modules to string together into the final product, so you can learn from his mistakes, and also know a bit more about what is actually important to the functioning of the modules. Above is a picture of the finished box containing the panel. Good luck with construction!

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Cooking: Refining the Recipes

Here’s a few pics of my “new and improved” Banana Pie, now featuring Ginger and mixed berries. By eliminating the extra juice and adding fruits that I foraged and some shredded ginger, I was able to both increase the sliceability of the pie and add a crucial taste dimension. It kept very well covered at room temperature for a day. If I had a fridge, I’m sure it would have kept longer and tasted good chilled.

Yum. This was a drastic improvement over the past recipe, though both were tasty. This time, I added: 1/2 ginger root, shredded; 10 blackberries; 3 ripe bananas, mashed; 2 passion fruits (foraged); flax seeds (enough to coat top of pie); and graham cereal to top (a nice thick coat, added after cooking, to cover the browning of the bananas). Cook covered for 1 hour. Make sure you shred the ginger very fine, and mix well or spread evenly, unless you like your desserts “spicy”.

Crab and Artichoke Frittata. Next, I attacked the egg “jello” recipe, hoping to solve a little of the texture problem. This time, I used: three eggs, lightly beaten, but not totally homogenized; 1 small can crab meat; 1/2 can quartered artichoke hearts (not the marinated kind, the kind packed in water); two pinches crushed sea salt. Cook covered for 1 and 1/2 hours. The result? The eggs did have a slightly better texture, but I’m thinking that the texture is something iherent in the solar cooking process. The color issue did not improve (eggs turn brown in the solar cooker), but the result tasted good, especially when an additional pinch of sea salt was sprinkled on top before serving. No pictures here, as it wasn’t too photogenic, but it was a solid meal, and my cats went nuts for it, (and ended up eating a few human sized portions of it while I wasn’t looking!)

For a hearty side dish, I prepared carrot and black eyed pea succotash. Very simple, few ingredients, and tasted and smalled great. It was so easy I almost feel guilty calling it a recipe. I used: 1 can sliced carrots; 1 can black eyed peas; 1 t sea salt; 1 T sesame seeds. Mix all, and cook covered for 45 minutes, or until hot. Here’s the (predictable) result, which needed no extra seasoning to be palatable:

So there you have it: three “new” recipes for summer cooking fun. As I learn more about urban foraging (more about this in my next post) I am trying to incorporate locally found foods into my recipes. We’ll see how it goes.

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Solar Installation Class – Ohm’s Law

Okay, for all of you waiting for notes from the solar panel installation class, here’s the scoop. The first class was cool, there’s a big machine shop there, and as a bonus, we’re also going to learn about machine controls for wind systems. Nice! There promises to be lots of applied action working with actual solar panels, so I should be able to share some real knowledge of what works and what doesn’t. For those of you who’ve been with me since the beginning, we’re going to repair my solar panel (the inspiration for this blog!), too. Finally!

But of course, as with most things in life (and especially with electronics!), it makes sense to understand the science behind things before getting your hands dirty, or shocked in this case! So We spent the first class learning the basics of voltage, current, power, and resistance. Ever heard of Ohm’s Law? (Those of you having evil science class flashbacks, don’t worry, I wouldn’t share it unless it was quite necessary for your safety.) Here is Ohm’s Law for DC circuits.

P = I * E and E = I * R (“pie” and “ear” phonetically, to help you remember)

See? Simple! Only four letters! What does it all mean? Well, in a circuit, you have four things at work. First, Power. Power (the P) is measured in terms of watts. It’s the work being done using the energy in the circuit. So if you baked six pies, and your clown friend used all of them to cream the faces of his fellow friends, the power would be those six pies you made available for him to throw. When you hear talk about kilowatt hours, this is a measurement of how much power is produced and available to do work by a system. Or how much you are using, as reflected on your power bill. So, once again, that’s POWER (P).

Next up, Current. Current is a measurement of the electrons flowing through the circuit. You see, in order for the energy to get from one atom to the next in the wire, it pushes electrons down the line, carrying a charge (since electrons are negatively charged particles). This is what we think of as “flow”. Current is measured in amperes and is represented by the letter I (that’s “i”). CURRENT (I).

Third, you have resistance, which is measured in Ohms (it is Ohm’s Law, after all!). Usually, you will see resistance represented by the logical symbol R, but Ohms also have their own symbol, Ω. For the purposes of this discussion, I’ll stick to R. Resistance is what it sounds like, a measure of how hard it is for the electrons to jump from one atom to the next. It’s a measurement of volts per ampere (or how hard it is to push one electron from one atom to the next). It’s not a 100% rule, but usually, you will find that resistance stays pretty much the same in your circuit calculations. It is most affected by distance traveled, the width of your wire, and by temperature.  RESISTANCE (R).

And, lastly, there’s voltage, tying it all together. Voltage is also known as ElectroMotive Force (EMF), giving rise to the symbol for voltage, E. Sometimes you’ll see V for voltage, but here I’ll be using E. Voltage is measured in Volts (whew, an easy to remember one!). Solar panels, wind turbines, etc, are generally hooked up to 12 Volt batteries, either in series or parallel (we’ll get to that in a second), allowing you to store the energy produced by the panel/turbine. Common setups will run at either 12V or 24V, depending on application. So, rounding it all up, we have VOLTAGE (E).

POWER (P) – CURRENT (I) – RESISTANCE (R) – VOLTAGE (E)

Got it? Good. Now let’s start putting it all together. Using the formulas above, you will see that Voltage = Current * Resistance. So, when the voltage goes up, the current goes up also… they are directly proportionate. This is a VERY IMPORTANT CONCEPT in circuits. It’s the equation E = I * R, or “ear”.

The other equation, P = I * E or “pie”, is for figuring out how much power is produced by a circuit, and is equally important. Written out, it’s Power = Current * Voltage. In any given situation you’re probably going to know two out of four variables and you’re trying to figure one of the other two. With these two equations, you can always solve for the ones you don’t have already. Here’s an example:

If you know that you have a 12V battery and you need to get 72 watts of power to run your iPod, how much current do you need? By the way, current is usually adjusted by using bigger or smaller wires, because the size of the wire affects the number of electrons that can easily flow through at any one time. This is due to resistance, but I’m getting quite ahead of myself.

So using our equations, E = I * R and P = I * E, you know that E = 12 volts and P = 72 watts. So, the second equation can easily be solved: 72 = I * 12, or I = 72/12. This works out to I = 6. Since I is measured in amperes, the answer would be I = 6 amperes. If you then wanted to figure out the resistance in the circuit, you can now plug these numbers into the first equation: 12 = 6 * R, or R = 12/6, which works out to R = 2 ohms. Using two variables, you’re able to figure out everything happening along those wires!

Now let’s say you wanted to use a battery system supplying 24 volts instead. Simply substitute and do the above calculations in the same way. What did you get? Here’s the breakdown. Since E = 24 volts now, and P = 72 watts, then you should arrive at I = 3 amperes via 72 = I * 24, or I = 72/24, or 3! From there you can figure out the resistance of this circuit: 24 = 3 * R, and therefore R = 8 ohms. There is more resistance along this circuit than along the circuit running on 12 Volts, and less current.

Okay, so that’s Ohm’s Law (of DC circuits) for you! I’m a student too, so this is about as deep as I can go into the subject right now, but expect more detailed explanations and the reasons for knowing all this junk soon. Stay tuned! In the meantime, if you want to read more about Ohm’s Law and why it’s important, read the Wikipedia article here.

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Nurturing My Weed: A Fable

Okay, to go along with my previous post about foraging, let me tell you a brief story.  A few years back, when I had access to a place to plant flowers, I used to spend a lot of time in the garden watering, pruning, even just looking at my plants as they grew.  It was meditation of the best sort.  Well, one year, after the daffodils had bloomed, I planted a few overstock seeds in a planter and started watering, waiting to see what emerged.  When a plant did poke its head out of the soil, I was surprised (they were old seeds, and I didn’t know if any were still viable) and pleased.  I kept looking after it daily, watching it grow and wondering what sort of mystery seed I was raising. 

Still being relatively new to SoCal at the time, I didn’t recognize the leaves of the plant, and when buds formed, I was so excited.  Now I’d finally know what this lovely little planty was!  And so it bloomed.  A tiny little yellow flower, and then another.  Hmm, I thought kind of disappointing for a cultivated flower, but hey, maybe I didn’t give it enough love.  I kept on watering and hoped for the best. 

Now shortly after that, I was walking down the road one day, and I saw my plant, or rather dozens of them, growing on the side of the road.  My little plant, the object of all that devotion, was a weed!  I was not happy to make this discovery at all, especially since it was only days after I’d let the seeds from my plant scatter wantonly across all of my flower beds, and I was therefore looking at the prospect of having hundreds of them growing in my garden.  I went home, pulled the “weed” and did my best to collect the seeds I could see on the rest of the soil. 

Fast forward to this year, as I’m reading all the foraging books, and lo and behold, there is my “Weed” on the pages of the wild foods guide, listed as a particularly nutritious foodstuff for hikers.  What?  I killed a plant that would have fed me if I’d known better, and spurned it daily as I passed its brethren on the the roadsides of CA?  Never again!

The moral of the story is this: the things we think we “know” about the world are often just perceptions we’ve been taught that have little to do with the reality of a situation.  My disappointment in finding that the plant I loved was a common weed didn’t even compare to the disappointment I felt when I realized that I’d allowed myself to be swayed by common opinion into killing a useful plant.  I guess in the end, it’s all about making sure you learn from reliable sources, and educate yourself on all sides of an issue before you feel comfortable saying you “know” what you’re talking about. 

Wild Lettuce

For more information about wild lettuce, see PlanetBotanic.ca

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Solar Panel Installation (and Eating Your Neighbor’s Lawn)

Great news!  It’s been a while since I posted, but there are a slew of recipes that you’ll be seeing added over the next few days.  As few things in life turn out perfectly the first time, I have been refining the previous recipes and trying a few new ones, side dishes mostly.  Most have been successful, but more on that later.  Great news, you ask?  Yes!  I’ve just signed up to get certified as a solar panel installer.  This means that for the next eight months, I’ll be working toward completing the necessary coursework and study hours for the National certification exam, and hopefully getting some practical experience working with panels along the way.  You might be asking why this should interest you in any way… well, since I love to share, and since writing about things helps me to learn, I mean really LEARN things, I’ll be keeping a sort of study diary on this site.  So if you’re wondering where to start on that whole “watts vs. volts” issue, or if you need a little brush up on your high school physics or electronics (and who doesn’t?), keep checking back often to see if I’ve covered the topic here.  I’ll be using the SEI’s textbook on photovoltaic installation and repair, which is pretty much the best on out there as far as I can tell.  Class starts Wednesday, so more about that then!

In the meantime, I’ve been reading a lot about urban foraging.  It’s a huge topic with relatively few available references.   But starting with Christopher Nyerges’ excellent Wild Foods and Useful Plants guides and also covering specific guides to my local SoCal area, I’ve been out every morning hunting for food.  And it’s everywhere!  Did you know that most of the plants in your garden, never mind those that professional landscapers use in public places, are edible in one way or another?  Geraniums, pansies, daylilies, lavender, nasturtium, chrysanthemums, marigolds, roses and more all make tasty snacks alone or blended into recipes.  You can even replace some of the gourmet items in your pantry with wild alternatives, adding an exotic flair to your cooking.  For example, nasturtium seeds make an excellent caper substitute when pickled, and you can make jellies straight from your yard instead of store-bought marmalades. 

If you’d like to find out more about the plants of your area, I’d highly recommend you check out a book that specializes in your area and start looking for wild foods every time you go out the front door.  I have to admit that though I’d never even noticed what was edible before, now I’m finding myself distracted trying to walk down any street, looking at the possibilities.  And the fruit you pick is SO much sweeter than the one you buy, even if just in principle.  The book I just finished Edible and Useful Plants of California (can’t remember off-hand who wrote it) also included many great anecdotes about the Native American food and medicinal uses of various plants.  When moving away from reliance on the grid, you’d do well to know a bit about the native flora of your community.  And I hardly need to spell out its importance after grid-crash, except to point out that it will be the few months following immediate aid and before people’s sowed crops mature that will be hardest for individuals to survive.  If you know about edible plants, then you can sit happily munching on your neighbors’ lawns while they sit inside their houses panicking.  You might even get an “I told you so” out between bites.  How’s that for sweet justice!  Until next time, happy foraging!

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