Panel Fab Shop

[howlet]

  Wind Turbines and free electricity caught my attention when I first stumbled

across this website. I couldnt believe that someone so selfless and charitable actually gave step by step instructions to make and install an instrument that could liberate a person from having to pay for electricity. I immediately saved all the info for fear that this goldmine would be gone, swallowed up by greed.

  It took me a couple of weeks to realise that 1 or 2 good sized wind turbines wouldnt go over well with the neighbors or the local authorities. My yard is big, (approx. 1.5 acres) but I could still imagine the neighbors having a fear of my new found love blowing out and slinging a 15 ft. blade through thier house.

 Somewhere around that time I realised that there was more to this website than the pages that I had been visiting,(I can be very narrow minded). I started navigating a little bit and came across the Solar Discussion section. At that time there were quite a few people making homebrewed solar panels.

  I researched for months trying to find the most effective way to build a solar panel that could survive the effects of mother nature, in particular the problem of condensation. I have finally come to believe that the best way to make a panel that will last is to mimic the professionals. Cleanliness, cell stringing fixtures to ease the task of stringing and laying up, smooth solder joints and vacuum lamination with EVA and tedlar.

  I've built a 14'x 31' shop that is dedicated to fabricating solar panels. I have purchased a heat lamp vacuum laminator and I'm hoping to have it all wired and running today. I will post some photos along with any other helpful info that I encounter soon.

Jeff

[DanG]

I have enough cells to make fifty 12V solar panels, and have talked to anyone who would listen about DIY photo-voltaics. I've been researching PV array designs for a while also - the big question is what compromises on output are you willing to accept!

The first challenge is getting uncoated iron-free tempered 4mm glass on site cheaply. Traces of iron in 'green glass' absorb a lot of solar wavelengths the silicon wafers convert; then include 5%~ reflective surface losses at glass air-interfaces, and the reflection from front of wafers themselves and it become >35% or greater losses before the 12% efficiency of the PV cells...

Glassless panels; I talked with an engineer who spec'd marine PV panels using a silicone-based encapsulent on an aluminum back-plane mounting... He talked with paticular mirth of seagulls merrily peeling it off and eating it which ended that project. Other resin encapsulents need to have near zero shrinkage when curing to avoid pre-stressing modern thin wafers that will crumble them over time through expansion & contraction heat cycles...

Also note the EVA needs a tackifier treatment, either applied to the glass front plane around the peripheral borders or as a coating on the EVA sheet to maintain bond with glass, the original hot-melt glue gun sticks were nothing more than a low grade EVA and shears off glass easily. Perhaps light "invisible to the eye" etching of glass borders and a painting-on of EVA resin dissolved in a carrier solvent might fill the pores of the glass and allow the EVA sheet to bond for 15+ years in a homemade setting?

I have decided on using smaller module voltages than the commercial panels, the glass cost is by the square foot not the piece count, so anywhere from 6 to 12 cells per panel would allow longer usefull life. I have to count on the cull wafers I have to use failing from the original reason they were pulled, or previous mishandling, or what other ever fate befalls them; a small section can be replaced at a time and the glass salvaged for reuse. Glass about the size of old green house panels would be good, no need to stay with units of 12V in the age of MX-60 chargers.

Anyhow - one forum member is anxious to see ideas & methods you are adopting!

[howlet]

From what I understand, the losses due to reflection occur on both faces of the glass (4% per side), plus the cell reflection. The cost of glass treated with multilayered antireflective coatings is depressing also. As you say, there is  compromise one must accept. Ive been studying options and methods used in the industry. I read recently that some cell manufacturers dont polish cells after the saw cut, saying that the rough surface helps in absorbing rays. I wonder if the same would hold true in the glass cover? Your posting gives alot of food for thought.

Jeff

[tecker]

One other alternative is a thin sheet of urethane water clear I just recieved an order from smoothon and am going to try covering with that . I've not been sucessful at ordering glass and getting it tempered .I'm going to pour a thin sheet over a glass mold . The 220 product needs heat treating but after that has has some potiential. I too purchased 500 cells almost two years ago and while I have two panels made they are still in test boxes .  

[DanG]

Using the smooth-on product - I would be tempted to solder the wafers together and 'wave' table style dip them like candles; I have tried to figure out a method to pre-encapsulate the wafers (except back-plane solder points) but the heat damages the coatings. With silicon stabilized with reinforcing coating alot more options may be open in the quest for 15-year DIY panels.

If you run the string array through dip and let it drain off excess WHILE progressing up through the heatlamp cure stage would it give any advantages?

With each phase change optical transmission degrades - but being able to throw 25% more cells cheaply into string at will would sure make up it in a hurry...

Any thoughts?