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.

Even though I’m not one of those “go green – save the earth” types, this link pretty much explains what motivated me to explore building a first solar panel. Based upon what was learned depending on solar panels for our electric needs would be economically impractical.

Next time you’re looking at one of those “google ads” implying you can get free electricity by building a $200 solar panel to power your house and sell electricity back to the electric company keep the following in mind: Some things you can believe while some should be taken with a grain of salt, others with a block and still others with the entire salt mine. Just as there is no free lunch there likewise is no free electricity.

From what I’ve seen “going green” is about getting the green from my pocket more than exercising conscientious stewardship over the environment. The last electric bill I saw represented 33 days during the last part of November and first part of December 2009. Some of the coldest weather of the year was during that time and we use electric heat. Per day average was 77.5 KWH. Some days exceeded that and others were less but for the sake of this let’s stick with 77.5 KWH/day. A solar array with 23 panels, each producing 144 watts 24 hours/day would yield 79.488 KWH/day. Of course that would require sunlight around the clock so let’s figure winter time 5 hours light per day at 144 watts/hr and we’ll need 108 panels to get 77.76 KWH/day. Of course that is assuming sufficient light for panels to produce the full 144 watts 5 hours each day. Nice concept but not necessarily realistic. Figuring each panel costs about $250 to build 108 panels comes to $27000.

Solar panels sometimes function 20 years or longer. Commercial panels often carry a 10 year guarantee. Assuming 10 years with $27000 initial cost would come to $225/month just for the panels. Every year beyond that would be bonus bucks. Then again we need to add costs for array structure(s) to mount panels, battery bank(s) that probably won’t last 10 years, charge controller(s), power inverter(s) and various and sundry wires and connectors, not to mention efficiency losses. Then there is personal time and effort researching, designing, building and organizing everything. Yep, it all adds up.

Economics may not be the reason for building a solar electric system but there are a couple good reasons that encourage me to keep building. Aside from temporary outages due to storms, floods, earthquakes and other natural causes let us not discount the possibilities of terrorist actions, governmental intrusion or even total economic collapse. No, I’m not predicting anything but don’t discount the possibilities. In all of these circumstances I prefer to have a source of electricity that requires no commercially produced fuel. Gasoline, diesel, LP and natural gas could be too expensive or difficult (perhaps even impossible) to obtain.

Because sitting in the dark wishing I had prepared sounds highly undesirable, the next phase begins.



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!

When constructing a solar panel for outdoor use it is desirable for the cells to be housed in an air tight enclosure. That isn’t a problem using readily available materials. The problem is that even though it is air tight the enclosure has air containing moisture equivalent to the relative humidity the day it was sealed into the enclosure. As temperatures repeatedly vary there will be condensation cycles which will eventually cause electrical shorting thus shortening the useful life of the panel. A popular means of dealing with that is to encapsulate the cells with moisture proof materials. In this case the cells are secured in place making encapsulating pretty much out of the question. Dang!

Because the cells are already secured to the back panel, it appears the best option to add longevity is remove moisture from the internal air after the assembly is completed. Can that be accomplished? Let’s just say I have a plan. One thing for sure, the project (and costs) to this point aren’t going to end up sitting at the curb on trash day. Nope, the panel will be finished and used as intended until it no longer functions. In the meantime it will be good for comparison to future panel projects. Who knows, maybe it will serve as well and as long as the next panels constructed according to (supposedly) better methods. Wouldn’t that be a hoot?

So the project goes forward. Starting with the next post photos and detailed explanations of each step will be included. You will have enough information to be able to duplicate this project. That’s not saying you should do that since there are better ways of making solar panels but you will have the advantage of knowing the mistakes I made, techniques for working with solar cells to avoid the “oh shoots” (not exactly my words but trying to be polite) and numerous insights along the way. Following this experiment to it’s finale will get you well prepared to avoid my mistakes and economically build proper solar panels. Or you can go about the learning curve from scratch and consider the cost your tuition.

Video documentation of the next solar electric panel is the plan. Of course, that’s assuming a suitable digital video camera within the finances of an old guy on disability can be found. I believe in miracles, don’t you?

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.

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.