Monday, May 16, 2011

Urban Solar - Take 1 Post 2


Went to an event at the New School in NYC today about Hydraulic Fracking and its potential effect on NYC water. More on that later. (Hint: It's freaking catastrophic!)

So where were we in our little solar adventure? Ah  yes. Broken dreams.

As you probably know, solar cells, like the 6" x 6" monocrystalline cells I purchased are REALLY fragile. To put it in perspective, imagine a thin sheet of glass- maybe the thickness of 2-3 sheets of paper. The sad part is that I knew this going in and still managed to break the first one. Here's how:

I watched several videos on how to tab solar cells. Tabbing is what you call soldering the tabbing wire to the cells. This tabbing wire ensures that the current along the negative side (front) of the solar panel travels along the entire cell and can be linked to the next solar cell. Monocrystalline cells like mine tend to have 3 bus bars going down the front.  Polycrystalline cells have 2 bus bars, and amorphous cells have no bus bars. The tabbing wire is slightly wider than the bus bar and has solder built in, right on the tabbing wire itself. Each strand of tabbing wire should be cut to about 2x the length of the cell so that it can be run down the length of the front of one cell, then down the length of the BACK of the next cell.

Before you can attach the tabbing wire though, you need to use flux. The flux pen should be run down each of the bus bars in turn. It cleans oils and oxides off of the bars and ensures a better solder.
I took the flex pen and "wet" it by pressing it onto a small piece of aluminum foil. Nothing special about the foil, it's just what I had nearby. The liquid in the pen came gushing out. Ok, not like Old Faithful or anything, just A LOT faster than I expected. I was able to rewet by dipping in the pool of smelly brown/yellow liquid in my aluminum foil.

Now, super eager to get to the business of actually DOING something, I placed the solar cell on top of a piece of cardboard, to protect the table from the heat of the solder.


Withing a few seconds, the uneven distribution of pressure (aka ME) on the cell caused it to crack. This leads me to my first gotcha of the process:

  • The surface behind the solar cell should be hard, sturdy and absolutely flat. I've heard good things about using a clean piece of sturdy glass that has been laid on a hard surface (table, work bench, etc). The reason for the glass is that it helps dissipate the heat from the soldering iron and prevent damage to the cell. 
And why did I need so much pressure to solder the cell? The second gotcha is:
  • Get a (wo)man's soldering iron. This cutesy little 23 watt p.o.s. did absolutely nothing. It was unable to melt the solder on the tabbing wire. With a good soldering iron, you should be able to run the iron down the length of the cell in about 1-2 seconds and have a good solder. The wattage doesn't indicate temperature, it's a measure of the "reserve" heat. When you touch the tip to the cell, heat transfers to the tabbing wire, the bus bar, and the whole cell. At 23 watts, the soldering iron couldn't make enough replacement heat to get the tab solder up to the melting point. Sadness.

    So yeah, no crappy soldering irons. I'm getting a 40 watt tomorrow. I'll try with that and see where it takes me.So far, I have a pool of smelling yellow corrosive stuff, a cracked cell, and zero tabbing.

    Maybe I should have tried melting concrete instead. Looks easier.

    Melting Concrete with the Sun

    Urban Solar - Take 1 Post 1

    There are probably hundreds of videos on YouTube relating to DIY solar projects. Sometimes elaborate, sometimes rather sparse, but almost always in some back yard, shed, garage or what have you. That makes sense, since typically, cities aren't exactly the best place to start trying to set up Solar PV panels. But I'm a geek. And I was bored.

    My goal is simple: Build a custom solar panel and use it to offset some of my vampire load in the apartment. Before you flame me:
    • Yes, I know the amount I offset will likely be tiny
    • Yes, I know that this will likely take 5+ years to pay for itself
    • No, I am not crazy. I mean, I don't think so.
    Why offset vampire load and not charge a battery for later use? First of all, deep cycle batteries, a charge controller, and DC/AC inverter can get pricey. This is meant to be a fun project with a tight budget. Plus, every time you convert energy from one form to another, like electric to chemical in a battery, you lose some power. Let's be honest, I won't exactly be producing gigawatts here. Every little bit counts. Lastly, who wants to deal with large heavy batteries? My "solution," if it works will pump juice right into my home grid. I should get some fire insurance.

    So that said, I have an apartment with generously sized windows in NYC. They face downtown and "West". If you are familiar with NYC, you know that "downtown" is South-ish. And "West" is "sorta-West", at least as far as the Earth is concerned. I'll stick with South and West, and in true NYC fashion, let you conform to my naming conventions. ; ) See below:
    (notice, no shadows! Unless Mr. Trump comes in to grace us with another one of his buildings, I think I will be shadow free for a long while)

    Now what? I don't have $1k+ to drop on a solar panel, an inverter, mounting supplies, batteries, etc. So I purchased some used supplies off of Ebay. These included:
    • 30 Grade B Monocrystalline solar cells (NOT panels)
    • Associated tabbing wire, bus wire, and flux pen
    • A really subpar, completely inappropriate and unusable 23 watt soldering iron
    • A dinky 300 watt Grid Tie Inverter
    • A multimeter (actually, I owned this already)
     If I laid them all out on a table, they might look like this:

    In my next post, I'll explain how I went from a bright eyed solar novice to this:

    Off to dream up my next post.

    Who, Why, What, Where etc

    The Green Frog. Who? Me!

    The name stems from a series of synapses firing in what seemed like a logical progression of thought. The trigger was that my actual name is already taken as a Twitter handle. I joined really late (4 weeks ago?). So I had to get creative. Take my first initial, few letters from my last name, throw in some Spanish and a nod toward my sustainability interests, and (E)LSapoVerde is born. Since I invested at least 18 seconds in the creation of that name for Twitter, I figured I should use it again, to get the best ROI on my time and ROA on the name.

    So here we are, but where is here? Well, this is my first ever blog entry. And this is the space where I intend to collect my findings, thoughts, and rants regarding CleanTech, Sustainability, the Green Economy, Renewable Energy, Alternative Energy (/shameless keyword plugs) and perhaps even my noisy Harlem neighbors. Maybe.

    So let's begin then. I'll start with my urban solar project. Who says that people living in a sardine can stacked 10+ stories up in the air can't do solar PV in their "homes" ?  Why do the private houses get to have all the fun? I'll show them.