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24 April 2006 @ 06:09 pm
Solar power and job news  
Where are my mechanically-minded friends at?

I don't understand electricity. All I know is that it comes through the wires and I turn things on with switches. :) Now I'm looking at this solar generator for emergency use, since hurricane season is coming. I would be using it to power a refrigerator/freezer continuously, and a box fan at night. Would this generator give me enough power to do so? Do I need the 5 watt or 10 watt panel? Is this generator too expensive? Do you know where I could get one that costs less?

Right, next topic. I start at the big firm tomorrow. There are two good things that I found out today. #1, I am still in consideration for the other job at this firm (intranet specialist) that I interviewed for. Also, they liked me very much. So that is still a possibility. #2, this one-month assignment is, as far as I can tell, actually open-ended. They've restructured the Conflicts department to have junior and senior positions. They've hired people for the junior positions, but not the senior positions yet. Another guy and I are going to be the senior positions on a temporary basis-- as far as I can tell, until they decide they want to make the positions permanent. So this very well may be temp-to-perm. Whee!

Send me good job karma! While I'm temping, I have to drive downtown every day. Once I find a permanent job, I can get in on or build a carpool. And I can afford a bike, so I can do errands on bike. As I get in better shape (and once it gets cooler again), I'm hoping to try biking to work (~20 miles) one or two days a week.

Man, I need money.
eaceac on April 24th, 2006 03:37 pm (UTC)
I can't remember whether I've said anything about this yet, but I'm impressed with your determination on this job hunt and money making problem. I think you've done a good job with it, and I'll bet you'll get really decent work soon.

Elle: I never wanted to be a startheletterelle on April 24th, 2006 06:37 pm (UTC)
Oh, thank you. I know you know how this feels, too. Thanks for your positivity. :)
DarkRiver: fiercesmolder on April 24th, 2006 04:34 pm (UTC)
Well, here is what I know.

You will need to look a the back of your freezer and fridge to get the exact wattage they require. (If it gives it in AMPS, multiply that by 120 for the wattage)

If they are like mine, the fridge will be around 800 watts and the freezer around 350. That's 1150 total watts, which means they will be running just under the maximum operating capacity of 1350. With a surge capacity of 3500, you should be fine with those two appliances, assuming your wattages are comparable to mine.

As to which panel to use, the page was not very forthcoming with what those were and the differences between them. I am guessing, since the 50Watt is smaller than the 100 Watt, it relates to how fast they charge from the solar batteries. Given that you will be putting it under heavy use, you probably would want it to be able to charge fast. But a salesman would be better suited to answer that question.
Elle: Call me Bubbles!theletterelle on April 24th, 2006 06:39 pm (UTC)
Thank you, sweetie! That's very helpful. I get it now. :)
Jer: Stud - Reichen (from Elrond50)lugonn on April 25th, 2006 03:35 am (UTC)
You've already been answered, but something to keep in mind is that the numbers listed for an appliance are peak Watts (or Amps). When the compressor kicks on with the refrigerator, then it uses the max power, but during normal idle conditions where it is just recirculating the air a bit or turning on a light, then it draws much less power. You should examine how long the compressor stays on when it kicks on, that would probably respresent the "surge" power draw mentioned in the ad, while the continuous power draw would be less. Similarly (but to a lesser extent) when a fan starts, that would be the surge, then sustaining the fan's speed would be a somewhat lower power draw.

Also, regarding the solar generator ...
How much power does it store for overnight use? Could the battery pack store enough to run the refrigerator all night?
How is the efficiency effected by overcast skies? Hurricane season is probably cloudy/rainy.
How delicate are the panels? You might not be able to deploy them until winds die down quite a bit.

A very full refrigerator/freezer/ice chest stays cool more easily than a mostly empty one due to the heat capacitance of all the already-frozen food and such vs. the low heat capacitance of air. So even if you are filling the appliance with ice, it is good to keep it mostly full.

If the battery pack won't last through the night, it might be good to make lots of ice during the day when the sun is providing power, and then the ice in the fridge will help keep it cool at night so less power is needed to keep the temperature down.

Your job prospects seem very promising. Good luck!

How is Rob's search going? I imagine this job of yours helped to lower the desparation you were both probably feeling.
DarkRiver: fiercesmolder on April 27th, 2006 12:20 pm (UTC)
A very full refrigerator/freezer/ice chest stays cool more easily than a mostly empty one due to the heat capacitance of all the already-frozen food and such vs. the low heat capacitance of air. So even if you are filling the appliance with ice, it is good to keep it mostly full.

You learn something new every day. *notes that down*
Jer: Stud - Reichen (from Elrond50)lugonn on April 27th, 2006 12:59 pm (UTC)
I just want to clarify. It takes more power to cool down a refrigerator full of warm stuff, but once chilled it maintains a constant (low) temperature more easily.

So if you have lots of power during the day, you could use that to make more frozen stuff. Then at night, the frozen stuff would slowly warm up when the fridge has little or no power to run the compressor.

Think of it this way. The turned-off refrigerator (due to leakage and such) will gain X amount of heat in a given time period. This is more-or-less constant and relates to the insulation of the refrigerator, the temperature differential between the inside of the fridge and the ambient temperature, how well the seals keep out hot air, etc.

So, if the refrigerator is empty, the X Joules of added energy (in the form of heat) is added to the air. Air has a very low heat capacitance, so a relatively small amount of input heat (X) will quickly heat the air.

By comparison, if the refigerator is full of goods with a higher heat capacitance (most any solid or liquid will have a higher heat capacitance than air), then that same amount of heat is evenly distributed between the air and all the items and it takes much more energy to increase the temperature of the solids even a little bit. Thus the increase in temperature inside the refrigerator is much smaller even though the system gains the same amount of heat energy (X).

Conversely, cooling an empty fridge is way quicker than cooling a fridge full of "stuff" since much more heat energy must be removed from the full fridge to yield an equivalent temperature drop when compared to the empty fridge.
vlynnvlynn on April 25th, 2006 01:16 pm (UTC)
wahoo! Definite wondrous job karma headed your way girl. You deserve it! :)
(Anonymous) on April 27th, 2006 07:36 pm (UTC)
Hey there!

I took a look at the solar thing. The problem is this: My Kenmore fridge (18 cubic feet size) pulls about 500-600 watts and it's a pretty efficient little thing. So you need to supply let's say 500 watts per hour for 24 hours=12 kilowatt-hours (kw/h).

The battery is a 60ah, 12 volt battery. So at *most* it could supply 720w/hrs. In other words it would power your fridge for about an hour.

This thing while cool is made for radios and small loads. It's not going to handle the bigger types of jobs. For comparison, I can run my house from the shed using my battery banks (8 100ah batteries, 3 200ah ones) which would give me 16 kw/hrs. Or a day and a half.

Other half is charge time. That 50 watt panel would take 720/50=14 hours of sun to recharge the battery. With my solar arrays on the house and shed I can recharge my batteries in 5 hours of sun. So as long as I can have sunny days I can get by.

A better bet at this point would be a small honda 1000i generator. They are quiet, reliable, and don't pollute much.


Elletheletterelle on April 28th, 2006 06:08 am (UTC)
Rock! That's incredibly helpful, thank you. :) Now I won't dump $1000 into something that's not terribly much use. I'll definitely check out the Honda generator.