1. Item Details:
These are mono crystalline solar cells that are made from solid piece of mono crystalline wafers, which produce the highest efficiency solar cells.
The cells were made by an European solar manufacturer. The solar cells generally measure 0.6v and 5 amp and above, but since these are grade B cells, some slight blemishes are possible. The blemishes can include slight off color, and some tiny chips on one edge may be possible - they are so minimal or only a few cells might have defects you will be pleased with them. Later on we will list mono solar cells with larger broken corners like those sold by existing mono solar cell sellers. The key difference here is that we have a team of people sort and inspect the cells in Silicon Valley before we sell them.
They are all packaged and shipped from Fremont, California. Overall they are very good looking cells and if you look at our feedback score you know we have high standards and mean business.
The cells have never been used - and they are not de-soldered cells. In this batch the cells should generally be between 2.1 to 2.6 watts each. If you test the cells under good sources of light and measure them with your multimeter, you should get close to 0.6 volts, and 5 amps + -.
Note: these cells are very fragile, so handle with even more care than dealing with our string ribbon cells when opening the package and soldering.
Open circuit voltage Voc: 0.604-0.623 V
Close circuit current Isc: 4.881-5.300 A
Maximum power voltage Vmax: 0.473-0.528 V
Maximum power current Imax: 4.429-4.924 A
Power: 2.1-2.6 watts
Dimension: 125 mm X 125 mm, or 5X5 In.
Thickness: 0.2mm, or 200 um
Tabbing wires: 300 feet of tabbing wires included.
Bus wires: 32 feet included.
Flux: 1 rosin flux pen. You need to break the seal by depress the tip of flux pen inward. When brand new the tip is dry. After breaking the seal, flux should moist the tip in a few minutes for fluxing.
4 Diodes: $6 value - rated at 15 amp each. Schottky style diodes.
Buy a smaller quantity package from us, and if you like them, buy larger quantities for volume discount. If you don't like the cells, return them to us, no problem!
Basic knowledge in electricity and power:
The basic and very important formula you need to know to make sense of solar cells is this:
Power (P) = Current (I) Multiply by Voltage (V), or P=I*V
Power's unit of measure is watt,
Current's unit of measure is amp,
Voltage's unit of measure is volt.
It's important to understand the concepts of series connection and parallel connection when stringing these solar cells together to make a solar panel. Series connection of the cells increases voltage but not amperage; parallel connection of the cells increases amperage but not voltage. Series connection is when you connect the positive terminal of a cell with the negative terminal of the next cell. Parallel connection is when you connect the positive terminals of all cells in the set of cells with a tabbing wire and all the negative terminals of all cell in the same set. You can use a combination of series and parallel connections to get the right voltage and amperage for your solar panel.
To make a 18 volts panel, for example, you connect 36 cells in series (36 cells times 0.5 volt each = 18 volts). 18 volt panels are 12 volt nominal for 12 volt batteries.
Solar cells basics:
The front of the cells (blue side, aka Sunny side) has two thick white lines, called bus bars. They are the negative terminals of the cell. The back side, where the 6 square dots are, are positive terminals. Connect the tabbing wires from the bus bar of the first cell on one side to the three dots of on the back side of the next cell. That way you have a series connection. Repeat the process on the other side of the cells. In panel making you should connect all the tabbing wires on the front for all the cells first, then flip the cells over to solder the back side in a second step. Some solar cells such as SunPower cells have both positive and negative terminals at the back of the cells, but we don't have to worry about them. Most cells are negative on the front and positive on the back. The white color bus bars on front and the contact points on the back are made out of silver, and you should keep them intact. Apply solder on your them and the wires should bond.
Make sure that you test the cells under strong sun light with the front of the cell facing the sun, at the same time connect your meters to the right terminals. If you are inside the building, make sure you shine your sun simulating lamps onto the front of the cell while testing. Place the solar cells on a metal plate, and place your meter's positive lead on the plate, and that allows you to access the positive terminal of the solar cells while the solar cell is facing the light source. Put the negative lead of your multimeter on the bus bar of the solar cell. The time of the day and time of year you perform the test under the Sun determines the output variance of your tests, so make sure that you take that into consideration.
Solar panel configuration:
For those who are new to solar panel making or if you don't have an engineering background, here is our recommendation:
1) Make small panels first so you gain experience.
2) In most situations, make either 36 or 72 cell panels, and connect them in series. 36 cells give you 17.5 or around 18 volts or so. And 72 cells doubles that. These panels are very useful, and you will find a lot of matching products that will want to buy! For example, you almost always want to use a charge controller if you make your panels to charge batteries. Charge controllers usually come in 12 or 24 volt settings, which match your panels' 18 and 36 volts very nicely. Yes, your panel voltage should be 1.5 times the voltage of the battery you intend to charge. Connect more panels together if you want to tie to the grid, in which case, always use an inverter. However, we always recommend that the panels that you make for yourself be used in off-grid applications, such as charging your batteries to be used in RV, remote cabin, or marine settings. If you intend to connect to the grid, it is wise to buy the professionally made, UL certified panels.
3) For a lot higher voltage panels and configurations and connecting multiple panels to get high voltage, consult a professional. Just don't fry yourself. Remember that solar panels are always loaded with electricity when exposed under the sun. At high voltage even a tiny bit of current, when handled wrongly, can kill you, especially after you series connect many finished solar panels together.
If you want to become a serious panel maker, buy a good soldering iron whose temperature can be adjusted. Don't get a cheap iron. It's one of the most important tools you need to have. If you can't buy an adjustable solder iron, get one that's rated at 90 watts. Also when you solder, all you need to do is to apply flux on the bus bars and the backside contacts before soldering. Do NOT scrape off the whitish substance on the bus bar or the backside square contacts. Those are made of silver and must be kept intact. Just apply flux and solder the tabbing wires. The wires are already coated with tin solder so you don't need to use extra solder AT ALL. Use a smooth and continuous motion to solder the wires onto the bus bars of the cells.
We are not experts in power systems and the above are what we learn through experience but we share what we know, and you should take it with a grain of salt. Buy books written by experts or take classes from the pros. Some people just keep asking question and taking time from us without buying, and we love to give, but please be considerate. Our resources are not limitless.
The solar cells are very fragile so be very very careful when handling them. But out of all of the solar cell packages that we sent so far, broken cells via transit are relatively rare occurrences, though theoretically it's quite possible. We invested a lot of resources to make sure that the cells are well protected by a combination of foam pads, paper pad, bubble wraps, manufactured foam forms, inner box, and outer box. We have won rave reviews from our customer feedback on our outstanding packaging, just check our feedback so you can rest assured that your cells arrive intact. Our warehouse personnel take great pride in their packaging. And we are developing even better and efficient packaging solutions to bring the cells to our customers whole.
We weigh each package and everything is recorded and signed off before shipping. All shipping paper work is double printed - one for our customer and one for our record, so that we have documented proof that we have shipped everything that our customers bought. This is done to prevent suspicious claims of not receiving the goods. In extremely rare occurrences where cells were shipped short, we would gladly make up the cells that you paid for but didn't receive.
You might break some cells during panel making process, so we always give our customer extra bonus cells for free just to show consideration for our customers. The number and percentage of extra cells we give vary, and it's purely at the discretion of the management, but all of our customers have been pleased with the deal they get.
We ship worldwide.
We ship the packages via US Postal Service Priority Mail or Fedex for orders within the US; and via US Postal International Express Mail for orders outside the US. We buy USPS Delivery Confirmation for all of the shipments at our own expenses. For solar cell orders that are 250 and above, we buy 'Signature Required' so that you sign of the package as well, unless you tell us not to - we will still buy delivery confirmation for you. This will make sure that you receive the cells. Delivery confirmation will give us a tracking number from which you can see online that delivery has been confirmed, but no signature is required. 'Signature Required' features says exactly that, and it's different from 'Delivery Confirmation' by the Post Office.
For international orders, we are not responsible for your import duties, customs charges or other VAT's. And we don't know what the charges will be for each country. Do not get upset with us because your government thinks that you should pay extra. In actuality we would prefer to do business all within the United States, but we have some good customers from other countries so that's why we keep our international shipping program. We reserve the right to terminate our international shipping program at any time.