This set of new 6 inch x 6 inch monocrystalline solar cells by Everbright Solar are made by an American solar company that has produced solar products in the United States for decades. They are very wholesome cells with minor chips, typically in one place only, as the pictures have shown. Monocrystalline solar cells are made from mono ingots / wafers which produce the highest efficiency silicon solar cells on the market today. Compared to other 6 inch monocrystalline cells, these solar cells have three bus bars on the front and back, instead of two. These solar cells have never been used, and they are not de-soldered from failed panels and strings, so you can start from a clean slate, which is good for soldering. We rated these cells at A- due to various minor defects, but we are confident these are some of the nicest cells you can possibly find.
When making high power panels, it is very important to include bypass diodes in your panels construction. And we are very happy to include the exact same diodes that are used in 70% of the professionally made high power panels in the world in this listing. We are the exclusive distributor of these diodes in the United States. We actually personally visited the factory that made the No. 1 dominant diodes. We purposefully package the highest rated diodes - 15 amp that are used in solar panels today, so that you don't have to worry about the diodes's capacity being two low. These diodes, when installed in parallel in your junction boxes, are actually bypass diodes; but you can also use these diodes as blocking diodes if you connect one of these diodes in series at the positive lead of your solar panel. Make sure that the diode's side with a ring points towards your battery if you want to prevent power from leaking from the battery to the panel at night. Our 15 amp diodes are powerful enough to be used between panels and make sure that electric current goes one way. You can use these higher rated amp diodes in lower amperage environment, but not the other way around. Since the total cost of a single diode is not that much, we decide to sell only highest power diodes in all our listings, so you don't have to worry about under-capacity. Please also note that these diodes are schottky barrier diodes that superior to other rectifier diodes which incur a LOT more power loss than the ones we are selling here. Please keep in mind that these are the EXACT same diodes that biggest pros used in their panels, so you can not go wrong with these.
The following are a little more details regarding this kit: (72 solar cells, tabbing wires, bus wires, flux pen and diodes)
The standard cell specifications are the following, though the individual cells can be above or below these standards.
Cell Specifications: Rated power : ~4 Wp
Open circuit voltage: 0.610v -0.621v
Short circuit current: 8.18 amp - 8.78 amp
Operating voltage: 0.488 v - 0.50 v
Operating current: 7.51 amp - 8.14 amp
Weight: Just above 6 grams, or 0.2 oz.
II) Tabbing Wires: additional 240 feet of tabbing wires to connect the solar cells. Cut them into 12 inch sections to solder onto the bus bars or back side of the cells.
III) Bus Wires: additional 24 feet of bus wires. Use them to connect them between the series and connect the tabbing wires ends to the junction box at the back of the panel.
IV) Flux Pen: an easy-to-use flux pen that dispenses flux onto the bus bar or your tabbing wires without leaving a mess. It's used to aid soldering and bonding of the wires to the cells. A must have item. The flux liquid in the pen has a seal. At first use of the brand new flux, remove cap, hold the flux and point the tip upward, press the tip inside a few times so that the liquid can flow to the tip later on.
V) Diodes - 2 diodes rated at 15 amp each. Schottky style diodes.
Some useful information in making solar power
How to make sense of the above numbers:
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.
So in our solar cell's specific example, if each solar cell is rated at 1.75 watts on average, and the voltage is 0.5, you do a little algebraic math, then to get the amps (I), since P=I*V, so I = P / V , therefore I (amps) = 1.75 watts divided by 0.5 volts = 3.5 amps.
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.
The cell specifications above were given to us by the manufacturer as averages. Variations are possible. To make a 18 volts panel, for example, you connect 36 cells in series (36 cells times 0.5 volt each = 18 volts). And 36 * 1.75 (each cell in theory averages 1.75 watt) watt = 63 watts. The amps you will be getting is 63 watts divided by 18 volts = 3.5 amps. 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.
Testing: 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.
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.
Soldering: 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.
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