Starting off small scale

[Steve]

Well it seems I am extremely lucky this time.
I had the cells temporarily placed on a portable table (See below) and somehow they have recovered from my alcohol debacle and once again deliver 6 (Shorted) amps in full sunlight with both panels placed in parallel. (The other panel is above this one, cut off in the photo)

When I used the alcohol, it seemed to wipe out the crystal patterns on the cells. The patterns have returned nicely.


I don't know what made the cells return to normal. When I put them into the sun yesterday they looked really bad- just an almost solid murky blue color and almost looked burnt. Maybe being out in the sun and in use fixed them?

My last photo here highlights the tiny strain relief bends in the tab wire. I made them using my finger to bend it around a small nail brad. Three bends per tab.

I don't believe there are any sharp bends anywhere and hope these curves will absorb and distribute some of the movement across a larger area.

Today I picked up the tempered glass from the company. Everything is moving on schedule. I have all the cells glued with the special silicone he gave me (It won't attack the hermetic seal) and everything is drying.
I am hoping to return them back to the glass company for sealing in 2 days.

Once sealed the only thing left in construction is applying a 3/4" aluminum U channel frame and making the electrical terminals on the back.

I am one VERY happy camper.

[Steve]

I am trying to decide what type of electrical plug to use for my panel.

Has anyone tried the pigtail plugs/sockets used for automotive trailers? They are polorized, it seems their corrosion is minimal in extreme exposure and able to handle a load.

[Mike90250]

This sound liks a ambitous project - and I am glad you are documenting it well. I really like your graphics you have done.

most alcohol has water in it, and the water may have gotten into the pores of the cells. Pure alcohol won't damage the cells themselves, but may remove some fancy coatings. Check that with your vendor.

Today I picked up the tempered glass from the company. Everything is moving on schedule. I have all the cells glued with the special silicone he gave me (It won't attack the hermetic seal) and everything is drying.

More important, what does the sealer smell like ??? If it's acetone cure (smells like acetone) no problem. If it's the common Acetic Acid (vinagar smell) sealer, that will ruin the metal contact areas on the cell, and damage them and reduce the output.

[Steve]

Thank you Mike as always for your suggestions. You are a wealth of knowledge and appreciated by everyone here. I am hoping I can learn enough about this topic/hobby to eventually help others with some form of experience.

Ambitous? Yes, that's an accurate description. I'm employed with a major communication utility repairing networks and it consumes 90% of my time. I've taken 2 weeks vacation to devote as much time as possible and I need to finish before Monday Aug 2. My main schedule goal was to complete 2 panels and obtain the major components. Panels are almost done, I have the right batteries and an inverter. The only thing I am lacking is a charge controller which we'll get in a few weeks.

There is also the Mrs. factor.
This expensive project simply must be completed within budget and time to complete satisfaction or the whole idea is dead. ... LOL

In the mean time I called my glass guy and he ordered some new rubber sealer to replace an aging stock so I'll hopefully have them sealed tomorrow. Except for fingerprint cleaning of the glass, they are 100% ready for him. So far me and the Mrs. consider the cost of the glass, the hermetic sealing, cost of the cells and countless hours tabbing etc worth it. I think we are making a good product.

$209 Glass, sealing included
$110 72 cells with tab & bus wire & flux pen
$6 Caulking from the glass guy
$72 (x2) 220ah batteries
$75 PowerBright 1100/2200p watt modified sine wave inverter
$600 = Total including this-and-that + tax

Labor - I didn't keep track but estimated 10hr. That includes trial and error in learning a new thing. But the labor cost is arbitrary because I truly enjoyed the whole process.

Photos this morning- I set them out to take some readings and to finish any drying of the caulking, and to top my batteries:


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Wired in parallel they deliver 16.3v @ 6.3a through the glass at 1:00 my solar noon. Both panels are pretty much horizontal as seen in the photo. I also took a reading at 10am. It was ~18v @ ~4a.

I expect a little resistance coming from one panel due to the wire & clips I used to connect the two in parallel. Both of those wires are about 2.5 feet long and 24 or 28 gauge with mini-clips as seen. I tested at the (Disconnected) batteries. I have a temporary 150' 20 gauge wire between the panels in the photo and my two batteries which at the moment live inside the garage. Maybe the ah will be a bit higher once "real" wire is used throughout.

My glass guy is using a 1/4 x 1/4" sealer. It turns to a hard-ish rubber. If/when the cells fail I should be able to open it up to replace them but with a lot of effort. Maybe cut the seals in half with a jig saw. At least I'd be able to reuse the expensive glass.

Speaking of glass:
Has anyone tried using rain-x on their panels? It would keep the water from pooling on the surface and probably resist acid rain etching. Easier to clean too. Only drawback I can see is necessarily re-applying it monthly.

Another question:
Can I use a common battery hydrometer purchased at any auto store to test my deep cycle golf cart batteries or is there a special type?

[Mike90250]

Comment - I see in the bottom of the last photo, you have a single piece of tab wire between the rows. I'd double that up if it was mine.

Auto hydrometer - same for deep cycle batts. Be sure you adjust properly for tempetures.

[Steve]

Thanks.
Now that you mention it, the conductor between the rows appears in the photos to be a single tabbing wire. It is actually 24 gauge twisted copper wire which I had tinned. This has been a learning experience and I made a mistake using my bus wire on the + side of each row end. I only had a small amount of bus wire left which I needed for the power feed-out through the seal so I used the 24g and tinned it mainly to help avoid the green corrosion.

I might just double them up tonight.

[Steve]

Both my panels are 100% finished on time.

I took Mikes suggestion and beefed up my cell row interconnections with a short jumper of 14 gauge wire and brought the assemblies back to the glass man.

He put 1/4 x 1/4 strips of special rubber around the perimeter of the glass, leaving a small space between the strip and glass edge. The rubber had an adhesive edge which stuck to the glass. The outside edge of the rubber was foil or metal. He had a special sealing machine that pumped what looked like hot tar at 400 degrees around the edge to fill up the space he left between the rubber seal and glass edge.

It looked really good but the tar was sticky even after it cooled so I cut some strips of heavy tin foil and put it onto the gooey edge.

I cut some edge framing out of 1/4 x 3/4" aluminum U channel making 45 degree angles for the corners and glued them onto the glass with the special silicone he gave me (RTV I think it is) and slid the channel onto the glass and silicone. I put a strip of flexible plastic between the buss wire and the channel for insulation.
I put a secondary bead of silicone all around the edge of the framing and trimmed it off nicely. The 45 degree corner cuts on the aluminum framing could be a potential leak so I pumped them full of silicone and applied aluminum tape, and a thin film of silicone over the tape. All of the extra silicone sealing was done front and back.

The wires:
I cut two wire strain reliefs out of scrap automotive plastic. It's the plastic they use under the car for splash guard and siliconed it to the glass, running the wires through drilled holes. I roughed up the surface of the plastic with a grinder for a good grip of the silicone.
One big mass of silicone applied in 3 stages seal the 14 gauge wire and buss terminals and also serve for more wire strain relief.

I believe that's the best I can do for them. If they don't hold up out in the weather at least I gave it my 100%.


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They weigh about 40lb each and I have to decide on a suitable mount.

[jockellis]

Making panels

If you are going to make a panel from scratch, visit a sign company which makes neon signs. They will have scrap .040 sheet aluminum and plexiglas from their odd looking signs. They would probably rather sell you the stuff than have to haul it off eventually. That's what I did. Actually, I used to work there so they gave it to me. Other pieces of aluminum and fiberglass screen will be at your hardware store. So will a lot of the electrical stuff. Ace now carries more electrical "stuff" than does Radio Shack.

[Steve]

Thank you for the reply jockellis.

The reason I used tempered glass on both sides is for even expansion and contraction as the panels heat and cool. I believe the glass itself will be more durable and less prone to warp etc than plexi. One of my biggest concern was the air and weather seal. I'm not sure if plexi can be hermetically sealed due to its low melting point. That type of seal seemed the easiest and probably the best and the glass man was happy to do it for me.

You're right about Radio Shack. I remember how they were back in the 60's-70's and how much it has changed.

[Mike90250]

...I'm not sure if plexi can be hermetically sealed due to its low melting point. .......

Actually, it's body passes water vapor. So, you can make it watertight, but not vapor proof.

[Steve]

I have an update.

Both my panels have been outside since 08-01-10 and have been doing great. There isn't any sign of water or moisture penetration. They have been sitting on a temporary deck table ever since then, but today I completed their outside mount. Here it is:


Bigger front view
Bigger rear view

The panels themselves and the mounting frame together probably weigh almost 100 lbs. Both post holes are almost 3 feet deep so it won't blow over.

I was concerned the wood frame might warp under the weight of the panels so I put an additional spar underneath to hopefully prevent this. I also painted the wood frame with UV resistant polyurethane.
The frame is fairly well balanced and the tilt angle is held in place by a single steel strap.
I can take my VOM to the panel itself and adjust the tilt for maximum output and adjust the tilting strap. I plan to do this once every month until I get all 12 adjustments.

I was using a 24 gauge 100 foot wire for their temporary use, but now have them on 50 feet 12 gauge burial grade wire to my batteries.

The wife says she likes the way it looks which means a lot. That, along with her reference of wanting "more panels" can only be a good thing for my developing solar project.

I too like the way my project is working out.

[russ]

Well done Steve - looking good!

[Mike90250]

Good move to get rid of the 24 ga wire !!

[Steve]

Hi, it's been a while so I wanted to update about my DIY panels.

Both are still working great. They've been outside since Aug 2010 and the enclosure shows no sign of wear. No sign of moisture penetration and they seem to do well in sub freezing temps.

I've inspected the cells over the past months and a single cell has torn/split parallel to the tabbing strips. The tear effects about 1/3 of the cell, but since it's between the conductors I don't think it really matters very much.

At least the panels continue to produce as they always have.

[Steve]

Just another update.
My panels have been producing for the last 7 months now and show no signs of moisture penetration. So far I've been more than happy with them.