Thoughts on these panels as a used buy
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Northernchateau
Solar Enthusiast
How old are they and what shape are they in?
8 years old and they all work
How many for $100?
In Australia you would be saving the seller tipping fees!
Go on Alibaba look up solar panels. The rate is 30c/watt...220w would then be $66/panel NEW ex CHINA.
Use 30c/watt...there are some much less...30cents allows for any currency diff between US/Aud/Can
Now drive around and find a Solar Panel dealer/installer operating out of a lockup garage or similar in your town's backsteets.
There you may see a container full of the latest panels just off the ship ready to be unloaded.
You may also see a pile of old panels.
Approach the operator and ask about 2nd hand panels, blemished new, or just new!!
Edit: Cash only and don't ask for a receipt.
In Australia you would be saving the seller tipping fees!
Go on Alibaba look up solar panels. The rate is 30c/watt...220w would then be $66/panel NEW ex CHINA.
Use 30c/watt...there are some much less...30cents allows for any currency diff between US/Aud/Can
Now drive around and find a Solar Panel dealer/installer operating out of a lockup garage or similar in your town's backsteets.
There you may see a container full of the latest panels just off the ship ready to be unloaded.
You may also see a pile of old panels.
Approach the operator and ask about 2nd hand panels, blemished new, or just new!!
Edit: Cash only and don't ask for a receipt.
Last edited:
iamrich
Solar Addict
I paid $46 shipped for my 250 Trina panels (used). If I could have picked them up it would have been $33.50, Obviously prices are not the same worldwide, but that seems expensive to me assume "under $100 is still close to $100...
The ones I am looking at are about $80 a piece. Also near me are some Trina 250 for $100 each, so yeah I'd say prices vary by area.
chrisski
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For any panels you buy, just make sure you get what you need. Panels can be hard to add on if you can’t find ones with the same voltage as the one you got a good deal on. I got a really good deal on my first real solar panel, but I then had to find three more just like it to build my portable system. I just wish I’d waited until I knew what I wanted and I would have saved days of my time.
I've got another option: 3 Silfab SLG370m panels for $500 - $.42/watt. New in box. Can I string together an odd number of panels?
| Module Power (Pmax): | 370 Wp |
| Maximum Power Voltage (Vpmax): | 39.60 Volts |
| Maximum Power Current (Ipmax): | 9.35 Amps |
| Open Circuit Voltage (Voc): | 48.20 Volts |
| Short Circuit Current (Isc): | 9.93 Amps |
| Module Efficiency: | 19.00% |
| Maximum System Voltage: | 1000 VDC |
| Series Fuse Rating: | 15 Amps |
| Power Tolerance: | -0/+5 Wp |
I want to build an off grid system with batteries for emergency use, but possibly to take certain circuits out of my home's panel and run them off solar exclusively. So I will need to find the proper solar controller, batteries and inverter. I figure I will start with a smaller system on the roof of my shed, and just run some extension cords to the house and see how it all works, before trying to change the circuits inside the house
Hedges
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Wired in series you'll have 144Voc, 9.93A Isc.
Voc increases about 10% to 20% in cold weather depending on temperature and temperature coefficient of panels.
Charge controller must be rated at least 175V max PV input to take this. Often 150V (can't work), some 200V or more (Ok.)
Wired in parallel, you'll have 48Voc, 29.7A Isc.
OK for charge controller rated at least 60V input and 30A short circuit current.
You should get three 15A fuses, connect one in series with each panel, if you do parallel.
If you could get 4 or 6 panels, that offers more options.
The key is what charge controller (or hybrid or other inverter) the panels go to.
You should select everything to work together, and meeting your power needs, before buying part of the system.
Hedges
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So you need to identify the inverter and think about battery size, cost, max current.
If loads have motors, inverter needs to deliver 5x nameplate rating for a couple seconds to start it.
Those three panels total 1000W (STC), may deliver 850W peak. 4kWh/day in the summer, 850 to 1600 Wh/day in the winter.
Inverter and battery will waste a percentage, leaving maybe 1200 Wh/day. Maybe 250 Wh if inverter consumes 40W under no-load and is left on 24 hours/day.
It's a system design problem, and with a relatively small system you need to keep loads to a minimum. Not many household loads this can support during winter. Much better in summer.
I do have a physical constraint with the size of the roof on my shed, so I am trying to maximize the output for the square feet I have to work with. These panels's dimensions would allow me to add a 4th panel which would fit on my shed's roof, but the person selling these has 3, so I'd have to find a source for a 4th.
My idea was to run the dishwasher and washing machine off solar, maybe also the microwave. These appliances run for a limited amount of time per cycle, and only a few times a week, leaving time to recharge the batteries in-between. But would like to be able to run the fridge and freezer off the system if need be, but not 24/7 permanently. - so I'd basically not use the washing machine at all to prioritize the fridge, if that makes sense. My logic is that in an extended power outage, I can live without washing clothes, but not without the fridge
Hedges
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Who says the panels must fit within shed roof outline?
Mounting rails can extend out in one direction, panels in the other, creating perhaps 2' eaves. Just needs to clear the door (and your head.)
The panels are 190 W/m^2, which is 19% efficient, pretty good for packing watts in a small areas. A few are 20% or above.
Mounting rails can extend out in one direction, panels in the other, creating perhaps 2' eaves. Just needs to clear the door (and your head.)
The panels are 190 W/m^2, which is 19% efficient, pretty good for packing watts in a small areas. A few are 20% or above.
Assuming I mounted these vertically, these panels to exceed the vertical dimension of my shed by a few inches, and I could fit 4 wide without overhang.
Hedges
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Those can be massive loads, require a fairly big inverter.
If you want battery to recharge for multiple days to power a load you need a large battery.
Neither of those is very cost effective.
You could use solar to power phone/internet, and even refrigerator.
If you cycle battery nightly, a lithium battery supports high cycle life.
If you only cycle battery during a power failure, lead-acid can support a couple to several hundred cycles.
Refrigerator can coast through the night on ice. So you only need a car battery to supply motor starting surge. Find a way to turn off inverter when sun goes down.
Most cost-effective way to augment utility consumption is grid-tie net metering or zero-export. That inverter only has to handle peak PV output.
Backup system inverter has to handle surge loads.
If you want to spend a lot of money you can make a capable system.
850W of PV will produce 15,000 kWh over 10 years. Worth $2300 if your utility rate is $0.15/kWh (but yours could be 1/3 or 3x that rate.)
To save money you need to build the system for a fraction of $2300. To make a capable off-grid system you'll probably spend more than $2300 (the numbers will look better with a larger PV array.)
Hedges
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How windy does it get?
How about 9 panels, 40" overhang left and right, 40" overhang at top (or 20" top, 20" bottom)?
That's 6 panels portrait orientation, 3 panels landscape.
3kW (STC), now we're talking!
My thought was that either the washing machine or dishwasher only runs for about an hour per cycle, then sits dormant, so a small system should be able to run that, no? I wouldn't want it to actually take days to recharge the batteries, I'm just saying it might be days between uses of these type of appliances. Same with the microwave. How long does it actually run per use, 2-5 minutes, then sits unused most of the time. So yeah I'd need an inverter that could handle that, but the way I'm thinking most of the time the system wouldn't taxed at all.
As far as cost savings goes, I get that a small system isn't going to save me much on my power bill, but my concern is more for having emergency power that doesn't require gasoline. If there was an extended power outage, getting gas would become a problem, and I'd have bigger problems than trying to keep my whole house lit up like a normal day. If I can get some use out of the available power, all the better.
40" and I'm in my neighbor's yard, lol. And over my fire pit on the other side. I am space challenge on my house roof, yard, and shed roof. I'd love a full scale set up, but unless I create some monstrosity to hold all the panels, it just isn't happening
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