The rear panel was fabricated from several acrylic pieces glued together using silicone adhesive sealant. For some reason, one glued edge pulled away and warped toward the fragile solar cells breaking six of them. Oops! Two lessons learned: 1-sometimes the bargain basement method isn’t a bargain. 2-silicone isn’t the right adhesive for the job. Future back panels will be one piece even though my original panel may have been just fine if bonded with a different adhesive sealant material.

Most types of silicone adhesive sealant have three strikes against them when used in making solar panels: 1-It has poor adhesion to acrylic or polycarbonate. 2-Once silicone cures additional silicone will not adhere to it. Discovering a gap where there shouldn’t be one means disassembling, removing all original silicone and redoing the process. Yuck! 3-The method of encapsulation I’ve been considering uses conventional silicone to seal the backside of the cells. Not too desirable when the plan was to adhere the cells to the back panel with silicone and it doesn’t stick to itself and is marginal at best adhering to acrylic. Thus a fresh challenge: finding flexible adhesive sealant products that adhere well to aluminum and acrylic or polycarbonate.

One product immediately sprung to mind. Marina job experience using 3M 5200 marine adhesive sealant makes me believe it a good candidate for the purpose. The spec sheet says aluminum may need priming for best adhesion. It also bonds well to acrylic and polycarbonate. Considering it is frequently used below waterline, I’m willing to give it a try without priming. A tube of it is in possession and will be used in at least one of the larger panels.

The second product called Lexel was found in a local hardware store. A Google search turned up a data sheet with lots of info. Bonding strength to both aluminum and acrylic or polycarbonate though possibly a bit lower than the 3M product appears quite adequate for solar panels. Lexel is also less costly, probably because it is not designed for marine use.

Either product seems suitable for bonding and sealing front and rear panels to aluminum perimeter frames. It’s tempting to clamp the front and back panels in place until adhesive cure is complete and forget about using additional means of securing the panels. Only one problem: I’m an over kill champ. So just in case the adhesive sealant lets go I want to insure neither panel can fall off.

Oh, about my ‘over kill champ’ claim. Just ask my brother. On second thought I’ll ask and if willing he may spend a little time at the keyboard explaining why I have legitimate claim to the title.

Anyone with suggestions, experience building their own solar panels or knowledge of adhesive sealant products suitable for DIY solar panels and willing to share please feel free to comment. They will be much appreciated.

After exploring different dimensions and layouts using inexpensive CAD software installed on one of our computers, a combination of online and local comparison shopping took place. Buying aluminum bar locally is more expensive than ordering online. That may be subject to change as I continue researching local suppliers. Clear acrylic (AKA plexiglass) 30” X 60” X .080” thick are available locally for about $22 each. Going with different dimensions would mean buying 48” X 96” sheets at about $90 and personally cutting the pieces to size. Time required, the risk of ruining at least half a $90 acrylic sheet versus getting two 30” X 60” pieces for under $50 made going with already cut pieces economical and logical. So acrylic it is for both the front and back panels. Aluminum sheet can be used for the back panel but higher cost and added work electrically insulating the aluminum makes the acrylic a more practical choice.

Brief side notes here: First, mostly as a matter of economics .080” thick acrylic was chosen. Also available are 30” X 60” X .118” thick pieces at about $33 each. Tempting though it is, this first larger panel will incorporate .080” thick acrylic. Second, clear polycarbonate may be worth considering but was ruled out for this project due to cost.

Before actual panel construction begins a couple simple jigs and a suitable work surface is planned. Details including video are in the works.

The first order of construction will be cutting 1” X .25” aluminum bar to yield 2 pieces 30” in length and 2 pieces 58” in length. Those pieces will become the perimeter of the solar panel. It will look pretty much like this:

Perimeter Frame

The aluminum will be secured to one acrylic panel which will become the back panel. The soldered together solar cells will be secured to the back panel using silicone cement.

One thing learned quickly when working with solar cells is they are quite fragile so careful handling is important. Likewise once mounted into the panel framework it is desirable not to allow front and rear panels to flex toward each other causing potential damage to the solar cells. To assure that does not present a problem 3 aluminum spacers .25” X .25” X 48” will be incorporated between the acrylic panels:

Frame With Spacers

Six inch square solar cells will be used and configured into four rows with nine cells per row.

Cells Layout

Once all soldering of cells is completed the back sides of the cells will be facing upward and will then have a coating of silicone cement painted over them to provide encapsulation. When the silicone is cured, dabs of silicone cement will be placed on each cell, the frame with back panel and spacers will be lowered into place over the cells and the silicone will be allowed to cure and bond the cells to the rear panel. When cured, the frame with cells in place will be flipped over and the cells front sides will then be encapsulated with clear optical grade silicone cement before sealing the front panel in place.

Complete Assembly

That’s the down and dirty version. There is considerably more than detailed above but you will just have to keep coming back for all the sordid details as they unfold.

The panel in use on the back yard storage shed measures 20 X 40 inches, produces a maximum of 63 watts and was completed mostly on the kitchen table. The next panels will measure 30 X 60 inches and produce a maximum of 144 watts. The kitchen table won’t work with the larger panels for a couple of reasons: FIRST is “she who must be obeyed” and she ain’t going for that again. SECOND is with 30 X 60 inch panels the kitchen table ain’t gonna fit. Considering there will be more than one panel built, a dedicated surface for securing different jigs to speed production seems a good plan. Garage cleaning is calling (arghhh).

Once garage cleaning gives sufficient space for the project it’s full steam ahead. I’ll start with one panel (the money thing gets in the way once again). Wild axed guessing tells me day to day needs will require four to six panels to keep a travel trailer battery bank rockin’ n rollin’. So even though one panel won’t do for the trailer it is both a start and good to have in case of an emergency situation. Having an electric source (even if limited) versus sitting in the dark with no electric seems a no brainer and in the meantime it is one step closer to the goal.

Peripherals include a battery bank, charge controller(s) and DC to AC inverter(s). Depending on your purposes the battery bank can be little as one battery or many as you can justify. Charge controllers come in a wide variety whether off the shelf or DIY. For starters I plan to build a simple charge controller capable of handling 20 Amps. It should work well with up to two panels. If you have no electronics hobby experience you will be ahead of the game buying an off the shelf unit. When it comes to DC to AC inverters, they can be DIY projects but there is generally no advantage and may actually be more expensive than commercially available units. Due diligence researching charge controllers and inverters is recommended. Give careful consideration to the cost of buying ready to use units versus component costs and personal time invested building your own. You may well conclude the only thing gained by doing it yourself is the pride of successful accomplishment.

Next post will include some nitty gritty basics of the panel design planned for this project. Small details regarding materials and dimensions can have an effect on per panel cost. This post is way over 500 words already, so stay tuned for the next installment.