Tweet
So first off, hello to all! I am so glad that I found this forum, there seem to be some quite knowledgeable people on here. Anyone want to share some of that knowledge with me? I am new to solar but have been reading enough about the subject to be able to discuss it. So let me start off by saying that I am not one of these dudes that has 36 cells, some Duck tape, a piece of plywood, and wants to "experiment". At the same time I am not able to cut fat checks for a big ol' Sunny Boy either. I will be DIY the whole way but, I want to DIY-it RIGHT! So here is what I have: Aprox 450 new un-tabbed 3x6 cells, aprox 1,200 3x6 new cells that I have already tabbed on the - (front) side, 12 Aluminium frames to fit 72 3x6 cells (24 volt setup) 12 pieces of CLEAR (low Iron) tempered glass rated for 100MPH winds and 25lb per sqft snow loads (one with a nice fat scratch about 8 inches long on it), 30+ year silicone for sealing around the edges of the glass and between the corners of the frames, clear encapsulation goo from Dow Corning Chemical, 4 quarters (so far) of a computer and Electronics Engineering degree, determination. The rest is up to you guys, and that is what to do, and more important what not to do (not fond of shocking the piss out of myself). So my main question (for today) is about testing my cells to weed out any duds before making panels with them. I have a multi-meter made by Ideal, two of them actually so I can check them against each other, I also have a 250w High Pressure Sodium grow light to have a steady source to test them under. I have heard the you need a 0.15 Ohm resistor to do it right, is this true? What is the best way to go? I don't want any duds in my panels, please help! Thanks in advance for any tips or advice!
-
-
I am going to help you out by asking you a two questions followed up with a couple of comments and facts.
- Do you live in the USA?
- What do you intend to do with these DIY panels?
Here is the deal if you live in the USA there is no code compliant way to use a DIY panel as part of your home premises wiring system. You will not be able to pull a permit for any construction, not will any electric company connect you without passing inspections which you cannot pass without a permit and inspection. No insurance carrier will cover any damages if you decide to bypass the system of check and balances.
About the only thing you can do with a DIY panel is use it on a detached building like a tool or garden shed for an off-grid system to charge batteries. But that even comes with a disadvantage because your panels will cost more to build vs buying and fail within a year or two.
So what are you going to do with those panels?MSEE, PE -
King, thanks for your reply. I am going to used them to AC my wood shop. I live in NC, hot most of the year. The Dow Chem encapsulation goo ad hears the cells in an airtight state directly to the glass and is made just for this use. How would it only last two years?Comment
-
So no info on how to test cells OR on WHY Dow Corning put all of this money in to developing a product just for PV use that you say will not work, but not WHY. Got it, awesome. So the companies that make panels that are ul rated have magic stuff they build them out of that none of us mere mortals can buy? Thanks for "helping me out" by telling me I can't do it.Comment
-
Dow Corning Chem PV-6010 MSDS Wonder what the PV might stand for, It CAN'T be Photo Voltaic 'cause "it wont work for that"!
Anyone besides our most helpful "King" have any tips on testing the cells and if a 0.15 Ohm resistor is required to do it right?Comment
-
Sure you can test cells. For a DIY rig you will need a good amp meter and test on very bright sunny days around noon. Manufactures use a special test lamp and test apparatus costing a few hundred thousand dollars. They sell their rejects to Flea Bay buyers on a penny to a dollar, and then re-sell to you with a huge mark up of 1,000 to 5,000%.
It is a great product if you are a manufacture using a $200K heated vacuum press. It also generates some income from DIY types who do not know batter.
You can buy manufactured grade B panels for $1/watt and they come with a warranty and UL certified.MSEE, PEComment
-
I agree that it is cheaper to buy the panels, and for any "on grid" stuff I would, just wanted to see what I could do. It is a lot cheaper to buy a crate motor from Jegs or Summit then to build your own too, but the last 388 Stroker I built for my friends Monti will lift the front right tire with 24's on it. Always up to learn somthin' new is all. And I have messed around with some of this PV-6010 stuff and it self levels (for days) as well as spitting out any bubbles, and drys to the texture of a plastic fishing worm. As for the Sunny day at noon thing. The sun is always fluctuating so that is why I got the grow light so as to eliminate that variable. Sure they will test lower from the lower light but it should still give me a control so as to spot any extra low reading cells when they pop up. What about the resistor thing, anyone know?Comment
-
Again no Resistor is used, just a Hall Effect amp meter with a known light source. Manufactures use two test methods.
1. is the Isc test through a dead short with a special test lamp.
2. Is the Imp using the same test lamp through a MPPT tracking resistance which is dynamic and not a set value under computer control. You cannot duplicate the test with a fixed resistance.
All you can do is the Isc test and your results will be inconclusive because you do not know the input light level.MSEE, PEComment
-
So what do you guys talk about? Different ways to bolt stuff to roofs? lol! I was not trying to whine. King what about the short circuit Hall effect thingy? Thanks again!Comment
-
King, so I could use my grow light and that Hall effect thing. How do I know if either of my meters is that kind or not?Comment
-
Russ, all of the DIY solar sites and forums that I have found have ya hoos cobing together a bunch of cheap un-safe crap that my 14 year old could tell you is not gona last long. THIS forum seems VERY knowledgeable and I would much rather be the "dumb guy" on this site and learn something than to be the "smart guy" on one of the other ones and act like I know something (cause I don't).Comment
-
Search for Tektronics TCP312 current probe.
For a budget device look for a current shunt with a maximum current reading just above what your cells will generate. A good precision shunt will run around $10 to $40. This is the resistor type you have referenced too. A 5 amp 50 mV shunt is a precision .01 ohm .25 watt resistor. But it will introduce errors causing you to read low values especially with a low level test lamp. .MSEE, PEComment
Comment