A Solar Conversation

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Hello, I’m Genevieve Jones and I am an amateur scientist.  I gave myself this moniker because I am, and have always been, insanely curious about the world around me.  Despite the fact that my life has taken me down a path more based in the right side of my brain I have always been curious about matters of science.  I have been drawn to science recently to help me interpret some of the scarier things that have been happening around me; things that are a lot larger than I am.  Things like climate change, pending earthquakes or the Mars Rover.  It just seems like a general knowledge of science could aid in my survival… if something bad were to happen.  Am I sounding like a conspiracy theorist?  I don’t mean to, I just live in Los Angeles, home of numerous earthquakes and celebrities who like lizard people.

Go with me on this.  Let us say there is a major earthquake or a tsunami or a storm system that rocks the coast.  Let us say this catastrophe brings down the structure system that we as Americans have grown to rely on.  If grocery stores and power plants and gas for your car were no longer options, what would be the hardest loss for you?  I for one would miss my laptop.  Now, I know what you are thinking: “Genevieve, if there is a grid crushing event of apocalyptic proportion you will have no need for your laptop.” To this I’d say: “How dare you speak that way around my laptop you luddite.  I will need something if I say I will need something.  How else will I decompress after milking goats and crushing grain to flour to feed my neo-family in my post-apocalyptic utopia?”  To that you might say something like: “I’m just being practical. You literally will have no use for a laptop during an apocalypse as the Internet will surely dissolve, printers will become obsolete and there are far more reasonable things to hit a zombie with.”  I would likely reply: “With all due respect madam, you are being incredibly daft.”

It is for this reason that I have decided to investigate a way to run my laptop off of a solar panel that I will mount on the roof of my apartment so that I can write after the apocalypse and post it to my tumblr.  It is my belief that by preparing myself thusly I will be ahead of the game in the event of worldwide calamity.  For more information about solar panels I went to my friend Michelle’s dad, Ron.  Ron is truly a renaissance man after my own heart.  With expertise in motor cycles, electrical engineering, camping, lasers, general tinkering and great recipes for a margarita to be sipped on a Baja dune at sunset, he is both the person you want in a crisis and sitting next to you at a dinner party.  Ron has also put in place two solar systems, which run his homes in Northern California and Baja, Mexico.  He was gracious enough to talk to me from his home in Auburn about some of the ins and outs of solar electricity.

The footprint of the solar array is about 50 ft by 10 ft; 6 ft high.

GJ: Hi Ron!  I wanted to talk to you about how you put your house down in Baja completely off the energy grid and outfitted it with solar panels.  Do you have a minute to chat?

RP: Of course Genevieve.  I’ll give you a little bit of an overview.  Connecting to the grid in Mexico wasn’t an option.  There’s no grid nearby.  So everybody in the community has solar electric.  One guy has some wind as an augmentation but by and large everybody’s on solar.  These are called off-grid systems.

GJ: How much electricity do you need to run your off-grid system?

RP: I wound up measuring what our energy consumption was there and it’s about five kilowatt-hours per day.  Let me give you an example.  A common light bulb size is 100 watts.  It’s a pretty bright light bulb, one you’d use for reading.  If you ran that light bulb for 10 hours- that would be 10 X 100 that’s 1,000 watt hours or 1 kilowatt hour.  And that would cost you about 11 cents to run that light bulb for the ten hours.

GJ: I see.  I am just going to turn some lights off… and… good.  Okay.  So, how did you measure your energy consumption?

RP: I actually bought off the Internet one of the utility grid meters.  You know that thing with the big round glass window?

GJ: Oh, yeah!  Those always made me feel like my house was secretly a spaceship.

RP: So I bought one of those and I hooked it into our system.  Not many people have that, but being a techie, I’m curious about such things.  Now, in round numbers five kilowatt-hours is about only 1/8 of what our home in Auburn uses where we have a different, grid-tie solar electric system.

The white box is the heart of the control system; it’s called the inverter. The panels are wired in series to boost the voltage needed for the inverter, about 320 volts DC. The inverter turns this into 240 volts AC, which is usable house current.

GJ: That’s right!  I forgot.  Your Baja house was first though right?  How did you get the materials to build your grid down there?

 

RP: We brought everything with us.  Our first system was solar panels that I bought from the Internet.  And those have been around for quite sometime.  I think you could buy solar cells going back even twenty years.  But as companies tooled up to make them more mass-produced the prices plummeted.  When we built our house in Baja the first panels that I bought cost about $5 per watt so a 100-watt panel would have been $500.  Now it’s down to about a $1.20 a watt and the panels are bigger so it makes them simpler to install.

GJ: Oh, that’s interesting, generally you think of technology advancing and things getting smaller.  But I guess the more area these cover the more sun they soak.

RP: Right.  And now that the panels are bigger there’s not as much interconnection.

GJ: And how much sun can these guys soak up?

RP: I think in round numbers one can assume that we get 8 good hours of good sun in a day, and if you have… let’s say for the purpose of discussion… actually it’s more like 5 hours because the sun rises low and it sets low.

GJ: The panels only absorb about 5 good hours of direct sun a day?

RP: Yes. That’s when the sun is high.  The optimal orientation is for the sun to be hitting the panels at a 90-degree incident.  So it changes through the year.  Summer will get more sun, wintertime less.  And it of course changes with the latitude at which we live.  One of the challenging things of a solar system like ours is how to store the energy for overnight use.  During the day it’s easy, we can use all the electricity we wish.  But overnight the refrigerator still needs to run.

GJ: Are you saying that the electricity generated by the solar panels is only a direct transfer, in that you only can use it as it is being absorbed through the cells?

RP: Yes, so actually in electrical terms, the solar panels put out direct current but the house runs on alternating current.  Our panels are all 24-volt panels and they charge a 24-volt battery- it’s a big heavy battery- that’s a couple thousand pounds of battery.

GJ: And you use that battery for power when the sun has set?

Closer shot of part of the solar array.

RP: Exactly.  Interestingly, the refrigerator is the biggest single demand of energy on our Baja house.  It’s about half.  So over-night is the challenge and we have to use batteries for that.  The batteries turn out to be the most fragile part of the system, though and they’re several thousand dollars to put in a set of batteries large enough to serve overnight needs.  The battery manufacturers say “they’ll last 8 or 10 years with proper care,” but experience shows that people will often have to replace them after three years.  And so, it’s tempting to think you get free electricity if you’re off grid, but if you amortize the cost of the batteries over the total number of kilo-watt hours you’ve generated it’s quite a bit more expensive than buying it from the grid.  But in this case, we need electricity to operate, so that’s one of the things that we face.

 

GJ: Does your system in Auburn, being a grid-tie system, avoid the use of batteries all together?

RP: Yes.  It’s a much larger system, it’s about 8 thousand watts.  We put it in about two years a go and it’s making more electricity than we use.  The great thing is about there being no batteries required is that it makes it cheaper for longevity and replacements.  The oddity of it being a grid-tie system though, is that if the grid goes down, there’s a power outage for example, so does the solar electric system.  It needs the grid in order know the voltage and to tie into the proper phase.

GJ: It’s disconcerting that these systems don’t run without the grid. If something truly terrible happened and all of the power went out – because of a large earthquake or something more catastrophic- your system wouldn’t be easily converted to an off-grid situation, right?

RP: Yeah, that is a shortcoming. There are sophisticated methods that get around that but none that I know of that would be practical for a smaller system. To run the 8 thousand watt system that we have in Auburn you would need to install a big package of batteries and yet another inverter. Now you’re adding… well. Just by way of commentary, our system that we put in at the house in Auburn was $24,000. And that’s net of federal tax credit, which runs 30% of the total cost. So if you put in the battery conversion system that would allow you to run when the grid goes down, that would add another $8,000 to your total.

GJ: I’m sorry, you did just say $24,000 not $2,400, correct?

RP: Correct.

GJ: Wow. That’s expensive.

RP: Yes, but then if you look at our bills and we’re saving in the neighborhood of $3,000 a year on electric bills. If you divide 3 into 24 that’s an 8 year payback. And I expect eventually electricity costs will go up so I’m thinking we’re ahead of the game. In terms of payback, it would have been more economically sound to put in a somewhat smaller system so that it would payback quicker. But being an electrical engineer I was sort of enamored of the idea of putting in a big system that creates more than we need and then figuring out something else to do with the extra. Something I might do is put in an electric water heater instead of gas.

GJ: And that would reduce your use of fossil fuels even more!

RP: Exactly.

GJ: So, if you generate more electricity than you need is there a way for that energy to go into the system and get stored so that other people who are hooked into the grid can use it?

RP: Yes. That’s what happens on an hour to hour basis. If we’re not using it, the energy goes back into the grid and somebody else uses it.

GJ: How great that that energy is not going unused!

RP: Correct.

GJ: I really like that because that means less people are using… now… oh, I don’t know what fossil fuel, or not fossil fuel runs the grid.

RP: Actually, it’s quite varied.  I think in California most of our electricity comes from hydropower, but in the southeast it’s diesel.  And in a lot of places in the Midwest it’s run on coal. … Barbra (his wife and lovely artist of steel and silk) just yelled that Canada runs on hydro because they have a lot of water there and much smaller populations.  There’s a geo-thermal plant up in Marin County but it’s really just a fraction of the total.  I think the bulk of our energy in America is natural gas or coal.  So as we can reduce that demand we can reduce the carbon footprint.

At this point Ron had to go “dispatch a call from the Sheriff’s office.”  I swear these were the man’s exact words.  Would you expect anything less from this modern day da Vinci?   For a moment I forget about running my laptop with an off-grid solar system in my Water World influenced Back Draft-colored fear for the future.  I think about how wonderful it would be if more people had grid-tie systems installed, off-setting more and more of our use of poorly burning, diminishing and water polluting fracked fuels.  I imagine that if enough people could afford to take these measures we might even be able to slow down or stop all together this Nicolas-Cage-starring-apocalypse I can’t stop having nightmares about.  Perhaps right now, solar energy has to do with the collective altruistic environmental value of reducing the energy load and less to do with my private dream of publishing my post-apocalyptic blog.  The only thing is, altruism sounds pretty expensive.

Join me for my second installment, where I decide between an off-grid or grid-tie system for my own small solar experiment and attempt to implement the virtues of solar in my own home.

Stay curious,

GJAS

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