Author Topic: Ebay Solar Cells (Read 6771 times)

Atokatim · « **on:** June 23, 2012, 01:21:52 AM »

Hello all once again! Long time no see. I have been doing a little searching for solar panels and have found these cells on Ebay for an extremely low price. I want to know if these are worth my money, time, or effort.

http://www.ebay.com/ctm/Solar%20Cells%20DIY%20Panel%20Kit%20Wire?nfItemId=270616538749

Here are some comments I have found about it :

http://pesn.com/2010/08/11/9501684_Do_Cheap_DIY_Solar_Panels_Save_Money/

Comments are located at the very bottom of the page.

Thanks!
Tim

Watt · « **Reply #1 on:** June 23, 2012, 03:06:30 AM »

I don't have any experience with those cells. Sorry. But, check out this thread regarding making panels. http://www.fieldlines.com/index.php/topic,145005.0.html

dnix71 · « **Reply #2 on:** June 23, 2012, 02:00:05 PM »

Waste of time unless you like to experiment and are off-grid (DIY solar will not be UL or CSA or UN listed). It is much harder than you think to make solar panels that will last. You will need low-iron glass and EVA laminate (which has gotten expensive lately), a vacuum frame and some trial and error.

You will not save money. You can buy commercial solar now for less than the cost of diy parts.

http://www.ebay.com/itm/WSolar-100-Watt-Solar-Panel-12V-UL-/140768362779

$1.80 a watt including shipping for commercial grid-tie suitable panels.

Atokatim · « **Reply #3 on:** June 23, 2012, 02:48:56 PM »

That is what I kind of figured seeing how many people who DIY solar panels fail horribly :p The project is for my shed as a test which is a 16 x 20 with AC / Heat, full electricity though out the whole shop, 220V air compressor, basic 350W computer with wireless internet, large laser printer, and 8ea 54 watt lights. If I could make this off grid, I know that would be a step to saving on my electric bill. Since I keep it at 72 degrees year round, it should be a prime area to install batteries and everything else I need attached to the shed.

I think I will go with premade panels anyways. The DIY way is very time consuming and I just was not sure about the cost. I want the cost as low as possible just like everyone else :p

dnix71 · « **Reply #4 on:** June 23, 2012, 02:59:57 PM »

To run the stuff in your shed/shop you would need a field full of solar panels and at least 2 large forklift batteries. You cannot live off grid like you live on grid without spending huge sums of money.

Just to run a/c on a cloudy day might take a football field worth of solar. Ask Damon about it. He lives in foggy England and gets less than 1/10 the rated power on some days because of the overcast.

DamonHD · « **Reply #5 on:** June 23, 2012, 03:15:39 PM »

You beat me to it!

You would do well to better insulate that 'shed', let the temperature range much wider or get rid of a/c, change your '350W' 'basic' computer for something like my 4W server or 20W laptop, etc, etc.

Do have any idea how many kWh per day you consume? My whole house uses 4kWh/day excluding heating (natural gas for that) and about 2500W--3000W of panels would approximately cover that over the course of a year if I spent more than the cost of my house on batteries. And we are at something like 25% of typical US consumption levels per person. (We actually have just over 5000W (5kWp) of panels which covers heat too from a carbon and money point of view.)

Rgds

Damon

taylorp035 · « **Reply #6 on:** June 23, 2012, 03:25:27 PM »

Quote

My whole house uses 4kWh/day excluding heating

My house uses that in an hour on average, 24/7/365....

As the other's have said, conservation and allowing a smaller delta T between the inside air and the outside air will be a better option.

Atokatim · « **Reply #7 on:** June 23, 2012, 05:00:56 PM »

The shed is fully insulated and is cooled by a small 5000 BTU 110 Window unit. The heating is from a small space heater and my solar heater from soda cans. My electric bill shows that my entire house and shed peaks at 4kWh/day. Average is 2.5 to 3.

The computer is a very basic computer that runs my DVR (home surveillance) system so it has to be on all the time for security purposes. Laptops can't handle being on all the time due to cooling capabilities.

I am also working on building a wind generator but have not finished anything with it due to experimenting with different coil designs to get the most power and usable generative area of the copper instead of the basic "V" type design.

dnix71 · « **Reply #8 on:** June 23, 2012, 10:01:44 PM »

Your numbers are inconsistent. A 5000 BTU window box ac with a SEER rating of 10 uses 500 watts average while operating.

If it runs only 8 hours a day that is 4kwh by itself. I live in an 14 x 15 foot apartment with an 8000 BTU window box ac that just barely keeps cool. I choose not to use it because of the cost. The electric bill you see below is mine. That's 4 kwh per month rather than per day and I run everything but a washing machine and a color laser printer from batteries and solar. My fridge is a 40 quart upright Engel that runs on 12v from the batteries. My laptop, dsl box, lights and fan also run from batteries.

It's not easy living this way, but I'm single and trying to prove what works and what doesn't and what is actually practical and what isn't.

Atokatim · « **Reply #9 on:** June 23, 2012, 10:51:27 PM »

The usage of 4kWh/day is my entire house and shed, not just my shed. I don't have a way to tell what my shed uses except to calculate the wattage of each thing plugged in or in use. I do have a kilowatt meter and have plugged it into my AC unit to see what wattage it used a few months ago. I don't remember the exact numbers, but I remember it was about $20 a month at $0.12 per kilowatt. The computer cost to run was somewhere around $12.

dnix71 · « **Reply #10 on:** June 24, 2012, 12:15:27 AM »

I'm trying to be nice because you are new here. Your reported 4 kwh/day (home and shed) use cannot be correct. A modern fridge uses about 1 kwh/day. A single 40 watt light uses 1 kwh/day. Your window a/c alone used 8 hours a day would use 4 kwh.

My neighbor lives in a one bedroom apartment. He complained about using 19 kwh/day (according to FP&L), so I got a KillAWatt meter and checked it out. His fridge used 1/day and the window a/c (12,000 BTU - 240 volt) used 12/day. His lights, tv and microwave used the rest. The average US usage is 30kwh/day.

My off-grid use is more than 1.5/day with no a/c. If you want to go off-grid you cannot run a window a/c without a forklift battery and a field of panels.

Your own math contradicts itself. The a/c you said cost you $20/month. That's 67 cents/day. If your electricity costs 12 cents/kwh then the a/c used about 5 1/2 kwh/day. The computer used $12/month. That's 3.3 kwh/day.

Where do you get 4 kwh per day for the whole house and shed?

Atokatim · « **Reply #11 on:** June 24, 2012, 12:59:17 AM »

Maybe I am misunderstanding the kWh / day part. I would have to find that sheet that I requested from the electric company showing usages per hour for a given date range. I think it is supposed to be 4kW per hour, not day :p I have done all kinds of energy saving things around my house and still have not seen a significant savings. The only thing I can think of right now to help save on the bill is to remove the shed from my house circuit.

I will re-plug in my kill-a-watt meter and check everything again tomorrow that I can and report back what I find out. My electric company here is pulling this crap where in the summer the cost per kw is more during the day for 8 hours and in the winter it is more during the night for 8 hours. They will not tell me the cost. From all of my calculations, I am guesstimating it is right around 0.12 average.

DamonHD · « **Reply #12 on:** June 24, 2012, 08:00:50 AM »

1) Make sure that you are very clear on the difference between kW and kWh.

2) Laptops *can* can left on all the time with a little bit of care: before moving all my Internet servers to the SheevaPlug (~4W) I ran them on a laptop (20W) for a long time; before that they were on a rack of Solaris machines (~700W).

http://www.earth.org.uk/low-power-laptop.html

3) When you describe your place as 'fully insulated' of course there is no such thing any more than a 'completely secure computer'. Are you insulated and air-tight to PassiveHaus levels? (U-values of 0.1W/Km^2 or lower.)

Rgds

Damon

Atokatim · « **Reply #13 on:** June 24, 2012, 10:08:32 AM »

I am not sure what the "PassiveHaus level" is but for a reference of what I think you are talking about is that when I close my shed door, the attic door pops open a little to push the pressure out :p Before I added insulation in the walls and ceiling then put sheetrock in, the little AC unit could not keep up during the hottest time of day. Now, the AC does not go higher than 74 degrees even on a 103 degree outside temp.

I used to work in a computer shop and I do know some people who leave their laptops on for several months in a row. They were in the shop more often than others with desktop computers and 99% of the time it was due to the laptop getting too hot and damaging something internal. I also don't own a laptop which does not give me the option to be able to use one as a replacement for the outside computer. In all of my computers, I do use Laptop Sata hard drives which cuts down on power consumption from the power supply. Even though the rating of the power supply is 350W, the average usage is around 125W to 180W depending on what is being run on the computer. I don't run a screen saver since that uses more video ram which in turn uses more power. I just shut off the screen. Same goes for my main computer in the house.

Not sure what you ment by "no such thing any more than a 'completely secure computer'". I am not worried about security on that computer. It has nothing on it but the DVR system and it runs on a different subnet mask than my other computer. They can't talk to each other.

Frank S · « **Reply #14 on:** June 24, 2012, 12:54:47 PM »

I would hate to think of how many solar panels and batteries it would take just to run my computer with its 850 watt power supply three 500 GB Hard drives 8 GB DDR2Ram,2 GB Nvidia 2 32" monitors the scanner the printer and all of the rest of the USB stuff connected to it.
the monitors alone are 160 watts each the PC has 5 fans in it. when I am running my cad programs and have several other programs open as well I sometimes get a warning that my system is having to run on virtual memory and that is with 8 GB DDR2
I have a 3 year old triplite UPS and 4 type 31 batteries that everything runs off of but if my power goes down I only have about 2 to 3 hours run time if I close every thing but the PC & the monitors. I'm on my computer 16 to 18 hours a day most days
I have a laptop and even though technically it has more computing power than my PC Winn7 "I" 7, 16 GB DDR3 1 terabite 2 GB nvidia, I consider it junk when it comes to having to do real work .
I don't know how you guys can work with your computers I am wishing that I had one with 128 GB Ram and 2 to 4 terabite storage 4 GB graphics and 3 monitors

dnix71 · « **Reply #15 on:** June 24, 2012, 02:10:25 PM »

A 4kw average draw is a very believable number if your daily temps hit 103F and you have a whole house a/c. That's 96kwh/day, which is about three times the average US household use.

If you want to save electricity, you will have to insulate your house like you did the shed and tune up the a/c in the house.

Other home uses of electricity are trivial compared to what is used cooling it in the summer. What do you heat with in the winter?

You didn't say why you have a large air compressor in the shed. Compressed air for tool work is not efficient, but it may be safer than electricity. If I was working on a boat in a harbor, I would want either battery powered or air tools.

Atokatim · « **Reply #16 on:** June 24, 2012, 02:57:13 PM »

The peak if 4kWh but the average is 2.5 to 3. The usage chart I have gotten ranges between 55 to 92 kW per day. Sometimes I have seen it go below 2kWh but that is usually when the wife and kids go out for a whole day. Since they stay home most all day, the wife and kids have lights on all the time, the TV on, washer going, dryer going, and whatever else electronic could be going :p I am fighting a losing battle. She told me she is not going to change her life style just to cope with how the electric company works (referring to the 8 hours a day the usage costs goes up). If I could have a system that would run my lights in my house and / or the shed, that would be a step towards saving on electricity.

The average temp where I live during the summer is around 95+ degrees. I have been tinkering with different cooling methods and learning about using ammonia to cool since I feel it is safer than propane since it requires a lot of heat to turn into a gas. I have also read that old steam locomotives used the exhaust steam to cool cabs. Not done a bunch of research on that. Every little bit helps IMO, so having different alternatives for each resource I use is a step towards getting my bills cheaper.

During the winter, I have gas heat in my house, but on my shed, I use a 7ft x 4ft solar heater I built from soda cans along with a small 1000W space heater. The solar heater is triggered by 2 temperature sensors. One is the inside thermostat, the other is an in-pipe normally open temperature sensor that kicks on at 140 degrees and shuts off at 110 degrees. When both sensors are activated, it turns on a relay that activates a squirrel cage fan that I have built into a box to push the air from the bottom of the shed to the top. It runs for about 10 minutes at a time until it is cool enough to deactivate the in-pipe sensor. Then it begins the cycle again. The solar heater on the shed was a test to see how well it worked before I built something to use on the house. Since the back of my house faces the sun all day long, I have a prime opportunity to use the sun as one of my energy sources. I also live at the top of a hill with very little trees around me, so wind is another option. Average wind speed around here is 10 to 12 mph.

The compressor in my shed is used for quickly rotating my tires on my car, pulling apart / assembling my engine(s), painting my car / truck, filling my tires when they are flat...etc.... It is wired to where I can shut it off and leave it off till i need to use it. It holds air perfectly and does not lose any pressure.

My goal is to slowly purchase solar panels and remove certain things from my house breaker and run them from my solar setup. I could also go with my local electric company buy back system where they pay me 0.22 to 0.24 per kWh. I would need to go with a grid-tied inverter and have heard that in the case of a power outage due to a downed power line, I would have to turn off my system so the workers don't get shocked. If my power is out, I want to be able to run on backup power. This is all still new to me and I have read alllllll kinds of posts on here for months. I feel like when I read, I learn more than when I ask a question. Sometimes I feel like people on here think I am an idiot and don't read, so I stopped posting questions.

Mary B · « **Reply #17 on:** June 24, 2012, 03:15:20 PM »

My average daily use last month was 15kwh and that was with the upstairs A/C unit running (no option, I have allergies and without it I can't breath). My computer system alone uses around 2.5kwh per day but this also includes the ham radio gear. Adding 520 watts of solar to help a little but it is mainly for emergency backup/run the computer part of the day. I need to get a gas water heater and lose the electric, that will help save a bunch. Yes Damon a more efficient computer would help but my 2 monitors draw 100 watts themselves

not giving up my twin 24 inch!

They do make a hybrid on/off grid inverter, look at Outback's offerings. Instead of the pop can solar heater go to buildit solar and look at the one made using furnace filter media, much more efficient. I am adding one of those this fall. I built one using the aluminum dryer vent and it works well but every extra watt of heat I can recover cuts the heat bill.

DamonHD · « **Reply #18 on:** June 24, 2012, 03:16:00 PM »

Hi Atokatim,

On your last para, you can buy grid-interactive systems with storage that safely disconnect from the grid when it goes down but keep things running at your end.

Rgds

Damon

Atokatim · « **Reply #19 on:** June 24, 2012, 04:02:02 PM »

That is another thing I am unsure about....selecting the right inverter. If they have the capabilities to switch between grid and off-grid, I am sure that is pretty expensive. The inverter seems to be the most pricey item at first next to the batteries, then panels, then charge controller. I need reliability, along with what's right for what I want to do with a little room to grow or the ability to "stack" them. I just don't know where to look other than OtherPower.com's inverters, but I am still not sure which to get.

dnix71 · « **Reply #20 on:** June 24, 2012, 10:50:41 PM »

Please do no try to use ammonia to cool your house. You will kill yourself and your family eventually. All sealed pressurized gas systems eventually leak. It's usually not that big a deal if an ammonia refrigerator leaks, because the amount is small, but a system big enough to cool a house will have enough ammonia to kill you.

If your wife demands lots of modern electric conveniences, then go here http://www.dsireusa.org/ and look up the incentives and programs in your state and locality to see if you can afford a grid-tie solar pv system. If you are paying $250/month for electricity having a pv system with battery backup would probably save you money in the long run and still allow you to operate off-grid when the power fails.

Even with a 5kw pv system, you still cannot operate a home 5 ton split system a/c on battery power. I have a coworker with a roof full of solar pv and she had to have a natural gas genset installed to run the house a/c if the grid goes down.

Atokatim · « **Reply #21 on:** June 24, 2012, 11:36:49 PM »

My average electric bill is around $175 a month. With just me working over an hour away from home, I don't have a bunch of extra income to dish out in large sums which is my biggest problem. Anything that costs around $500 takes me a few months to save up for. If I know what I need to purchase ahead of time, I can usually save up to purchase it without spending it on other things like my electronics I like to tinker with. I have been saving for quite awhile now to purchase an inverter since I know I will have to start with that. Why buy panels if I can't use the power?

The ammonia refrigeration is just a concept I am working with at the moment. I don't plan to have any ammonia inside the house since I hope to use a heat exchanger of some type for the transfer. I also plan on TIG welding all joints to ensure it can handle the pressures and heat / cold. The unit would be placed outside probably inside a shed of some sort.

Atokatim · « **Reply #22 on:** June 24, 2012, 11:46:59 PM »

Just checked out that link you sent me and here is about the best incentive I have for residential :

http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=TN02F&re=1&ee=1

I live in TN just outside of Memphis. My electric company is through Southwest (EMC)

vtpeaknik · « **Reply #23 on:** June 25, 2012, 04:36:59 PM »

I would like to re-iterate Damon's advice above, to keep KW and KWH straight. Can't have a useful discussion until the terms are consistently defined. A "watt" is a unit of power (energy per unit time), and a "watt-hour" is a unit of energy. And there is no such thing as "watts per hour" (nor per day). A watt-hour (not "per" hour) is the energy used by a 1-watt load (small night light) if it stays powered on for an hour. A kilowatt-hour is the same, for a 1000-watt load (portable electric space heater).

Atokatim wrote: "The peak is 4kWh but the average is 2.5 to 3. The usage chart I have gotten ranges between 55 to 92 kW per day." Those units are clearly reversed. That is because "per day" you use a certain amount of energy (KWH), while power (KW) is momentary.

The electric company charges you for cumulative energy (KWH), not instantaneous power (KW, unless you are an industrial user). Thus, for example, 55-92 KWH (not KW!) per day is (divide by 24 hours) 2.3-3.8 KW, or 2300-3800 watts, of instantaneous power, on the average, during the day.

To get that much power (say 3000 average watts) out of solar panels would take a much larger number of nominal panel watts, since the sun is not shining all the time. In a good solar location (Arizona) you'd need about 12,000 watts worth of panels, while in a poor location (England) you would need to double that (or worse). That's a lot of panels. The area covered by 12,000 watts of panels is approximately 1000 square feet, and their installed cost these days would be at least US$20,000 (just for the panels, without wiring, inverters, etc). If half the roof is south-facing (in N. hemisphere), and the house has two floors, we're talking about completely covering that half-roof on a 4000 square foot house.

First Economize, Then Solarize.

DamonHD · « **Reply #24 on:** June 25, 2012, 05:24:53 PM »

Not sure I like England written off as a "poor location"! B^>

BTW, the sunniest spots on Earth seem only to get 2x or 3x the insolation here, but maybe my sums are wrong.

In any case, the optimal 'capacity factor' of solar here is very roughly ~15%, so to get 3kW average would require 20kWp or about 160m^2 / 1600sqft and battery losses would in fact require bumping that up to maybe 200m^2 / 2000sqft, so twice vtpeaknik's estimate. And my roof is not south facing, so still more.

As it is I have just over 5kWp or about 40m^2 (which is my roof more-or-less full) to effectively cover our heat and light year round (using the grid as a battery, etc). In fact we are covering ~400W effective average at a capacity factor of about 10%.

Rgds

Damon

thingamajigger · « **Reply #25 on:** June 26, 2012, 10:52:27 AM »

@Atokatim

A few people have offered the standard retail solutions and if you can live with a 40+ year payback period they work well. I however am a firm believer in efficiency which also relates to the efficiency of my hard earned dollars in which case retail is the last thing I want. So rather than follow along like a good little sheep I developed real cost effective solutions that work.

First buy the cheap solar cells off Ebay because there is little difference between them and ones that cost twice as much in regards to bang for your buck, Watts per dollar. Next buy a cheap 4 x 8 sheet of white fluted plastic(has an air space between exterior surfaces) and loosely frame it in with 1" aluminum "C" track like the kind you can buy for screen doors and windows, slot the screw holes to allow for expansion. Next screw small plastic or aluminum rails to the plastic sheet to loosely hold the cells in horizontal rows or soft plastic tabs can loosely support groups of cells. This allows for thermal expansion and the 1" air space is cooled by natural convection to heat my garage. Remember efficiency drops as the cell temperature rises so it is silly not to cool the cells and use this heat for some practical purpose. Next the panel is covered with a 4 x 8 sheet of 1.5-2mm clear lexan or plexiglass and I use 1/4" aluminum "C" track with weather stripping and hinges so that the panel can easily be opened.

The thing to remember is that in Canada the temperature varies from -50C to +40 and once a summer I can expect near golf ball size hail, every ten years or so I can expect hail near potato size. I can tell you as a fact standard panels will not last long and to be honest they are usually not designed very well because the tight air space overheats the cells and hail will obliterate them in short order because the clearances are minimal. Efficiency does not mean a damn thing when your expensive high efficiency panel has been smashed to pieces by good old mother nature.

In any case I would take what the "Retail Experts" say with a grain of salt because most have seldom scratch built anything let alone tried to improve it, I have no interest in retail because it's a losing proposition after all is said and done -- a bad investment.

Regards
AC

dnix71 · « **Reply #26 on:** June 26, 2012, 05:48:32 PM »

Atokatim, I wish you had said up front all the details and that you wanted to cut your electric bill with solar pv. You can't make electricity as cheaply as you can buy it if your coop buys from the TVA. I worked for them for a year, many moons ago. I had $4 electric bills and that was a one bedroom apt with fridge, lights and electric space heat. The highest bill was less than $10.

You really should sit down with the wife privately and talk about money. If you drive an hour to work and are living paycheck to paycheck, experimenting in pv probably isn't wise. A $175 a month electric bill isn't really all that bad considering what you have, but you really shouldn't be living on the edge. Living closer to work, setting aside some money for emergencies (like car repairs) and knowing exactly where all your money goes would make a bigger difference in your family situation than trying to save a few dollars with homemade solar.

If you had the money to invest, direct solar pv grid-tie without battery backup would give you the fastest return. But it sounds like you don't have the money to invest.

If you heat water with gas or electricity, a thermal solar water heater system would pay for itself in less than a year. Thermal solar space heating for your house would pay for itself in less than a year if done correctly. That's something you can do with scrap material and make good use of your welding skills.

http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

Damon here has done that on his home and it works well. Ask him for more details.

DamonHD · « **Reply #27 on:** June 27, 2012, 01:56:20 AM »

Ah no, haven't done the solar thermal yet, though it is planned.

Conservation, ie reducing consumption, is about 10x better value for money than adding solar, and if money is tight and your loads are high then I know what I'd be doing too.

As suggested, it might we worth talking again to your other half about adjusting things to fit with how the electricity company works, etc, etc, to save the money (which you could then 'waste' on the fun things like solar!). Mine has after a little reluctance been really hugely helpful and keeps it together every day and helps me test ideas out...

http://www.earth.org.uk/saving-electricity.html#meter

Note that ignoring our PV we halved our natural gas consumption and reduced electricity consumption 6-fold. Our bills are a fraction of the national average now, and it wasn't massively hard nor degrading, and I know others that have done the same. Relatively few people bother which is a shame because it just is easy (and IMHO helps avoid CC). Plus the side bonus was the UK's energy secretary came round to see it. B^>

http://gallery.hd.org/_c/people/_more2012/_more05/Edward-Davey-Energy-and-Climate-Change-Secretary-DECC-visiting-a-SuperHome-with-aerogel-superinsulated-living-room-and-solar-PV-in-Kingston-London-England-1-DHD.jpg.html

Rgds

Damon

Mary B · « **Reply #28 on:** June 27, 2012, 09:54:30 AM »

See if your state or electric company is offering rebates on grid tie solar. In MN Xcel Energy has a $2.25 per installed watt on solar grid tie systems and the state had a matching rebate. I don't have a clear enough south view for them (they are very fussy, has to be clear from 70 to 270 degrees). Would have paid 100% of an install now plus a little extra.

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Author Topic: Ebay Solar Cells (Read 6771 times)

Watt