Solar Panels at Factor e Farm

(linked from Solar Cells)

Basic Design

• 156 mm square cells
• 4x8 cell panels, total of 32 cells per panel
• dimensions – 29”x56” for each panel
• 112 designer watts
• we have enough solar cells for 15 panels

look @ pg. 43 of hurley for an example layout of the panels. The example is 4x8 as well, though the cells are larger than in the example, about 6.14 in^2. These sound fairly large, about 2.5'x4.5'. If we are working on two at a time with a small team of people, we will need significant table space.

Parts

1. 3/16” Plexiglas – Lowes/Menards (L/M) – price:
2. case backing, aluminum – McMaster Carr or local sheet metal shop
3. 1” by 1/4” aluminum bar< 72.5'W+140'L-5'for corners= 207.5' good thing you don't have to worry about saltwater spray. imagine ordering this much stainless steel! This might be a bit much for local stores, we shall see
4. u-channel for edges (will we do clips or do full bars and drill? One will require more drilling, the other more cutting?? the difference will necessitate only about 5' additional. pg 96)
5. shrink tube – Shrink tube for wire exits @ junction boxes, 1/4”x7/8” x 30 (2 per panel)
6. window screen – L/M - suggests fiberglass insect screening medium. Must evaluate pros and cons of using metal or fiberglass. annot use metal, the purpose of this screen is to prevent conduction with aluminum backing, which would cause massive loss of voltage, thus a very fine screen made of nonconductive material would work best.
7. tabbing ribbon – need 12.5” per cell – total of about 520 feet! <rd pg 79-82. we might need more per cell, more like 15". it must run between the cells as well as along them. so, maybe as much as 620'
8. bus ribbon - estimating about 82'. We will need to do a scaled schematic/structural drawing to calculate this
9. stainless steel screws - assuming 18 per panel, at least 270, on pg 132, SS pan head slotted machine screw 10-24 1.5"L (or up to 2")
10. stainless steel machine screw nuts - at least270 Stainless Steel Machine Screw nut 10-24 screw size, 3/8" width, 1/8" height.
11. stainless steel 18-8 large OD flat washer 10 screw size 13/64" ID, 1/2" OD, .033" -.047" thick.
12. GE Silicone II sealant, clear (needed for junction boxes)
13. GE RTV 615 optically clear silicone Circuit Specialists RTV615-1P 1 pint (for 4 panels) - 1 quart (4 pints per quart correct?)
14. Xylene (xylol) solvent Hardware store 1 pint (for 4 panels) - 1 gal
15. 60/40 solder - or PB free silver based? For the health of the assemblers? Add'l cost for heavy metal health and safety protection equipment...- though 60/40 available locally @ L/M
16. 2-wire terminal - 300 VAC/VDC terminal block , 2 circuits, .69" center-to-center, 65 amps (adjust ampage to cell output)
17. wire for panel connection - assuming 1.5' per panel, 22.5'... what kind?
18. junction box - 15x Plastic case, 4.7” x 2.6” x 1.5”
19. epoxy for junction box - needed to withstand at least 400*F temps (suggested J-B Weld Epoxy, Max temp. 500°F or similar, 2 oz. tube
20. Clear plastic pony beads 1/4" Craft store 8 per panel, 120 Total
21. Silicone rubber strip 3/32" thick, 2" width 36" long
22. 15 Schottky diodes (shottky are a bit more, but .3 V drop instead of .7 V is important)
23. Rubber grommets for junction boxes (2 per panel, 30 total) to fit 9/32” hole exactly (no moisture!) (Rubber grommets, 8" ID, 11/ 32 OD, groove diameter 4", groove width 1/16", 3/16" thick suggested)

Tools

1. variable temp soldering iron x2 – may have to order online, will call -St. Jo L does'nt have
2. needle nose pliers - L/M prob. Must decide on what kind, what features needed esp. for crimping.L =

http://www.lowes.com/lowes/lkn?action=productList&N=0&Ntk=i_products&Ntt=needle%20nose%20pliers for selection and price list.

1. Plexiglas "plastic sheet" cutters - L/M prob. Not at L
2. Flux Pen 186FP Mildly activated rosin, type RMA HMC electronics - says 2 pens or as needed for 4 panels, so 6 pens? Not at L
3. Reamer bit? Not at L
4. 7/32 drill bit (might want an extra or two?) L/M. L=4.69 for cobalt, 4.97 for titanium
5. two brushes for encapsulant, addl. brushes for silicone. is foam okay for these applications?
6. Metal Rulers, Tsquare (Tsquare not absolutely necessary, I have a nice 1.5' metal ruler) Various choices at Lowes, ranging 6.50-14

Work Plan

Hope to have 4 people total. Lots of cutting, soldering, silicone and epoxy brushing to do. Split into two teams, rotating duties,

Duty 1: Soldering and wiring, Duty 2: Panel assemblage.

Since panels can be prepared before the cells are soldered together, these two tasks can be done simultaneously, saving time. Cutting will be taxing, so this will require lots of rotation, and will also require proper safety equipment. Cutting of U channel, aluminum bar, plexiglas, possible precutting of Tab and Bus? Having to cut as you go might slow down the process.

Will necessitate refreshments, possible gas reimbursement (its expensive these days!). Might have to have a beer or two at the end of the day...

possible schedule (who am I to set a schedule?) saturday: 8:00 wake up, work at 9:00, break at noon or one for lunch, continue til 7:00? 8hrs x 4ppl= 32 human hours Sunday: 8:00 wake up, work at 9:00, break at noon or one for lunch, continue til whenever we need to leave.

During the process, we need to be documenting it all with video and picture. Might want to borrow an extra camera.

I have Hurley's book printed and in a binder, so it will serve us well in shop. Might want another? We will see. Might be able to seperate cells and panel work sections.

Participants:

Still have to figure out who all is going. Vince says maybe, he is wigged out on working two jobs and can barely think right now. He will finish up MSA on saturday and probably spend two days sleeping. Sri, a friend from here in columbia, very scientifically minded med student and sustainability enthusiast says she really wants to go. Everyone wants the weekend of the 11th because the weekend I have been proposing contains independence day. What about grid independence day! We will see what happens. There are several more interested parties, including mike. We could end up with as many as 6 participants. I might try to come down the weekend before that as well, as sitting around watching fireworks doesn't seem to be an appropriate celebration of independence for me. A friend of mine from natural resources (spec. soil science) has also spoken of coming out the weekend of the 11th, pending his new job schedule.