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.

Not the Highest Quality Picture But You Get The Idea

First and foremost problem was the manner used to fasten the plexiglass front panel to aluminum frame. You see plexiglass and aluminum both expand and contract at different rates. Plexiglass is prone to cracking around holes drilled in it even though deburred. It appears my error was in not drilling the holes a bit larger in the “plexi” to prevent hole edges from pushing against the securing screws during cycles of expansion and contraction. Although not severely cracking the plan is to replace the original plexi come spring and adhere it in place using a non-silicone adhesive/sealant that will be permanent without screws.

Second problem was using aluminum channel (the type used as edging around plywood panels) rather than solid aluminum bar for the frame. The channel has less than desired rigidity after assembly and is less than ideal for accomplishing a water and air tight housing for the solar cells. With enough attempts I’m confident satisfactory frames could be produced using channel but advantages of solid bar stock for future panels is personally more attractive.

Third problem is actually not a problem but something to consider when planning and building your own solar panels. The 3” X 6” cells used in the first panel provide a maximum of about 63 watts from 36 cells connected in series. For charging and maintaining the 12V battery power needed in the back yard shed that small panel is quite adequate. Over the winter months the need is mostly for lighting from time to time and maintaining the motorcycle batteries. Cold as it is being this winter there will be little intensive work done in the shed. So the max. 63 watts provided by the smaller cells is proving to be a successful first solar panel experiment.

In the works is the next generation solar panel project/experiment. There are 6” X 6” cells available claiming 8 Amps (or 4 watts) per cell. Thirty-six cells in series would yield 144 Watts at ideal conditions (wild guess is in the real world between 85 & 125 Watts is more likely). The plan is to supply enough power for a 20′ to 30′ travel/camping trailer. Y’know what? Even for a do-it-yourself type doing it all on the cheap that strikes me as both a tall order and big dollar outlay.  Running a refrigerator and occasionally a microwave or other electronics will make charging a large enough battery bank a tall order. An air conditioner and electric water heater would make it an even taller order. None the less my fascination for this project continues.

So the second solar panel project/experiment is in process. The panel will: measure 30” X 60”, have solid aluminum frame, encapsulated cells and detailed text, graphics and video for each step of the process.

140 Watt 30″ X 60″ Solar Panel Layout

Over the past couple days attempts to add pictures have failed miserably. Some kind of blog software-hosting provider glitch I’m guessing. The hosting guru is digging around looking for the culprit but so far nothing.  I’ve postponed  this post long enough, time to publish it and edit pictures in when the problem gets resolved.

Ahhh! Sweet success!

The instructions not originally included with the solar cells only explained how to solder the included pre-tinned flat copper wire to the proper places. In other words nothing that wasn’t already known. Since learning little known secrets of solar panel building was what I had in mind, it was disappointing.

According to the seller each cell measures 3.25” X 6”. The truth is each is just over 3” and pretty much dead on 6” wide. Configuration for this panel will be with the cells in three 6” wide rows allowing 1/8” between each row. Each 6” wide row will contain 12 cells. Each cell is calculated at 3.125”. Actual outside dimensions for mounting the cells comes out to 37.5” X 18.25”. Although other configurations would work equally well, the three row arrangement made the most sense because it will require fewer pieces of flat wire and fewer solder connections.

Having decided upon the arrangement of cells, additional decisions regarding materials and assembly methods come into play. First was what to mount the cells onto and by what means. Second was which frame material to go with. Third was a choice between clear Plexiglas (acrylic) and clear polycarbonate at greater cost and greater durability.

Tough decisions those, but in consideration of this experiment, they pretty much fell into place: Initially I was going to mount the cells to primed and painted oriented strand board (OSB) but preparation and painting time plus the possibility of more problems keeping the cells secured in place brought me to some surplus 1/4” thick white plastic material available for $2/lb at a local discount hardware store.

Deciding on suitable edge frame material for the panel came next. For the sake of durability, fewest steps to finished product and little if any needed maintenance I chose aluminum channel designed to fit over the edge of ½” plywood. Compared to cutting, routing, priming and painting wood to make a suitable frame, the aluminum seemed the way to go.

Plexiglas (acrylic) was easy enough to decide upon simply as a matter of keeping experiment costs low while providing long service. Plus if a problem with acrylic crops up there will be no difficulty replacing it with clear polycarbonate.

My DIY Solar Panel Experiment is officially under way. There are eBay sellers anxiously awaiting feedback, and I’m hoping they will get my highest ratings.

Within the next day or two the adventures of soldering to solar cells will be revealed. There is a learning curve involved plus the cells are incredibly delicate. Stay tuned.

The solar cells arrived last week. Included with the cells was pre-tinned tab and bus wire, flux and solder. Not included was the “instruction manual” which the seller promised would be in the mail Monday morning. It hasn’t arrived yet but it is only Wednesday. Previous research and experience caused the temptation to just go ahead and get started anyway. I have resisted, just in case there may be little known methods, techniques and secrets within their information versus information gleaned from other sources. Somehow I’m expecting to learn very little more, but just in case, I wait.

Do it yourself projects usually start by mulling over what you intend to accomplish until the goal is pretty clearly cemented in the mind. General details, for that matter even intricate details are frequently worked through before anything gets put on paper, into a text document or a CAD drawing. In the mind’s eye the project is completed in seemingly no time. In actual hands on doing it, well the time factor expands exponentially or at least that’s how it feels. I hesitate to speculate how much additional exponential expansion will result from documenting with pictures (possibly videos) plus lots of instructive text and probably more. One thing for sure, it ain’t gonna be just making a solar panel and explaining what and how I did it.

I tell ya, some of the things I get myself into. OK, let’s not go there.

Each of the 36 cells produces .5 volt and 3.5 amps or 1.75 watts in bright light. So let’s do a little math here:
At .5 volt X 36 cells connected in series you get 18 volts which is considered good for charging a 12 volt battery (or bank of batteries). In other words: .5v X 36 = 18v

At 18 volts X 3.5 amps you get 63 watts. In other words: 18v X 3.5amps = 63 watts

Connected in series? Think of a flashlight that uses three C batteries. Each battery goes in the same way meaning the positive post of one battery is in contact with the negative post of the next. With three 1.5 volt C batteries placed that way there is a total of 4.5 volts to the bulb. If you have a flashlight that uses only two batteries it is 3 volts. If you have one that uses 4 batteries it is 6 volts. It’s the same when putting solar cells together – positive to negative and by chaining all 36 cells positive to negative there will be 18 volts in bright light.

There is a bit more than just connecting a solar panel to a battery or bank of batteries. There’s a chance of over charging, using more electricity from the battery than the panel can provide or even discharging the battery when low light causes reverse flow of electricity from battery back into the solar panel. Reverse flow can be prevented with diodes which prevent current flow from battery to solar panel. It is not a method I would use with other than very low power solar panels.

Solar charge controllers are designed to prevent battery overcharge, battery discharge beyond a preset level (usually 10.5 to 11.5 volts) and reverse discharge. Charge controllers vary from less than 5 amps to high amperage. For the sake of the storage shed experiment I’m looking at a $23, (shipping included) 15 amp charge controller from an eBay seller.
Project progress so far is limited to solar cells ($70), personal knowledge and experience (hopefully to prove of value), charge controller @ $23 if that’s the one I buy, various and sundry materials to mount cells into a panel (jury is out on that expense so far), power inverter (oh yeah, haven’t mentioned that yet), 12V battery (may just be a battery borrowed from a camping trailer for now) and who knows how many bits and pieces from the neighborhood hardware store. Yep, you’re seeing it as I do: this ain’t exactly what ya call free electricity. Then again, everything has it’s price.
The plan was to post this last evening (Thursday) but experience dictates not to publish to the blog when staying awake is a major problem. This morning (Friday) rolls around and while catching up on emails the doorbell rings. Amazing: USPS with a package addressed to me. Sure enough, solar cells!

Part three coming soon.

In the course of these posts the information and explanations will be kept as non-technical as possible. My experiences include beginner hobby electronics projects which at least provides a good mathematical background and practical electronic soldering experience. Add basic woodworking and metal working/machining to that and I’m confident building my first solar electric panel will be a learning experience and hopefully of benefit for a few Rantsville readers as well..

OK let’s start with a couple definitions as they will be used throughout this series:

Solar Cell: As used within these posts refers to a photo-voltaic cell which is capable of generating approximately .5 Volt when exposed to bright light. The surface area generally determines the amount of current (amps) the cell generates in bright light.

Solar Panel: A number of solar cells linked together so as to increase the voltage and wattage output. For example if you link 2 cells in series, each producing .5 Volt at 3.5 Amps the resulting output is 1 Volt at 3.5 Amps.

That’s the down and dirty basics. The intention for the first solar panel project is an experiment to help determine the number of panels will be needed to maintain sufficient charge in a bank of batteries in order to operate a power inverter for the appliances we want to use without relying on an electric company. Individuality will dictate what those requirements are, thus I will not even attempt to define appliances you deem necessary that we may not. To begin with all I need is a test subject.

Over the summer much spare time was devoted to converting the powder coated steel framework of a Harbor Freight tarp covered storage structure into serviceable winter storage for my ’95 Goldwing. Price was right and the work exhausting but it’s a sturdy structure with both mine and my brother’s bikes inside. An extension cord can be strung through the back yard for lighting but I prefer not to do that to prevent the cord from falling victim to our snow blower. Over the winter light will be needed when accessing the shed for whatever work we need to do, plus a couple of motion sensor flood lights to keep honest people honest.

The absence of snow blower fodder while still having lights, minimal security and (not necessarily scientific) data collection easily justifies this solar panel venture. Wednesday when my check gets banked I’ll buy 36 solar cells from an eBay seller. Properly configured they will provide 18 Volts at 60+ Watts in bright conditions. I’m curious to know if that will be sufficient for the shed.

Part 2 to follow.