Combine the power of two solar panels in style with this retro steampunk style solar combiner box. It features all analog meters to show the voltage of the individual panels, the combined voltage, and even the amperage being used. This combines the two panels in series and then outputs through a single cable to the charge controller box and looks good at the same time!

If you would like to support me in making these projects you can do so here.

Here is a complete list of Supplies & Tools you will need. They are not all the same supplies I used but should be similar or better replacements.

Disclosure: The links below are affiliate links. This means that, at zero cost to you, I may earn an affiliate commission if you click through the link and finalize a purchase. I am a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.

Supplies

• Plastic Container – (I modified a plastic container meant to hold playing cards but unless you have only lying around this one wouldn’t require any cutting of the individual plastic organizer dividers. You need one that can fit the analog meters in height, width, and depth. Some of those meters are around 2” deep.)
• Spade Terminal Wire Connectors Set – (This kit provides plenty of connectors in 3 different sizes.)
• Rocker Swich On/Off – (This is to be able to switch the solar panels on and off individually. It comes with a low gauge wire, for higher amp panels use a better wire.)
• Mahogonay Wood Vinyl Veneer – (This give it a very nice wooden look instead of clear plastic.)
• Copper Tape – (This helps hide the edges of the Wood Veneer above and makes it look more steam punk.)
• Ring Crimp Terminal Connectors Kit – (It comes in 3 sizes and 3 different ring sizes which makes it easy to find a close fit. Used on the analog meters backs.)
• 12 AWG Silicone Wire Spool Red & Black – (Two colors in a good wire gauge for wiring it all together. Silicone wires are very flexible which is easy to work with.)
• 2x Analog Voltmeter Gauges 0-30v – (Analog meters are much nicer to look at and give it the more steam punk feel.)
• Analog 0-100V Voltmeter Gauge – (I chose 100v because it would make the combined voltages of my panels be roughly the center of the meter. Be sure to choose one that is high enough for your combined solar panel voltage.)
• Analog Ammeter 0-30A Gauge With Shunt – (I chose a pretty high amp which is likely overkill for the panels I have but it does show the amp draw.)
• SAE Power Socket Sidewall Connectors (4 pack) – (These make it easy to plug and unplug your solar panels into the solar combiner box and have the combined voltage go out of the box on the bottom.)
• SAE Extension Cable with On/Off Switch – (This goes from the output to the Solar Charge Controller I liked having a switch built in so I can quickly turn it on and off when working on the charge controller.)

Tools

• Angled Wire Cutter & Pliers Set - (Any wire cutter will work but the angled one is very helpful for modifying the plastic later. This also has needle nose pliers which are also needed.)
• Hole Saw Variety Kit – (Variety pack of multiple sizes so we can find one that matches the analog meters.)
• Electric Drill – (I used a ryobi but any would work.)
• Tin Snips – (Very useful for cutting the plastic parts out.)

First I started by testing out all the meters and making sure I had the wiring correct. The two cables on top come in from two 100w solar panels on the roof. To make things easier I made use of a bunch of alligator clip wires to test the wiring and make sure the meters were working. A wiring diagram will be included in later steps. I tested the output through a basic halogen light bulb and you can see the slight glow in the pictures.

I had an old plastic container with dividers on the inside that will make up the housing of this project. You will save a few steps if the container you use does not have non-removable dividers inside of it as they will get in the way of the meters. This is also a good time to do a very basic test fit to make sure the meters are not too long to fit inside the box and will all fit on the outside how you want them to.

I made simple cardboard templates so I would be able to mark screws and locations. However be sure to use a stronger piece of cardboard then I did, I used cardboard from the boxes the meters came in and it was too thin and bent to much making it not work as well as it should have. If you want to skip this step and just use the actual meters that works as well and is what I had to do in later steps anyway since this cardboard didn’t work out. I included all the pictures here anyway.

I didn’t want any of the sensors to be too close to the edges and I wanted to be able to fit copper tape around the edges so I made a border of an inch on all sides. I used a notepad as a straight edge but a ruler would work better.

I wanted to try a few different configurations for the layout of the meters so I traced them on paper and drew a tiny meter on it because I could. This is an easier way to try a few different layouts to find which one you like the best.

Once I tried a few layouts I ended up liking my first one best so I marked the corners of the paper meters so I would have a rough idea where the actual meters would go.

If you did end up using cardboard templates now is a good time to trace them onto the box. I used this to line up the holes I drilled but the screw marks I did here did not line up since the cardboard had bent in many ways and was off.

Before drilling into plastics, especially plexiglass, it seems to help prevent cracking when you put tape first on both sides. I used masking tape for this part so I could still mark on it easier and not have it rub off.

Before drilling I redrew the templates onto the tape to help line up the drill. I marked the rough center using a measuring tape which was 1 inch for these 2 inch holes.

The multiple size drill saw kit I got requires some preparation in order to use which can be seen here.

I then drilled the first hole out and used a screw driver in order to get the plastic out of the drill saw. Predrilling the center hole with a drill bit would be a better idea.

When doing a test fit I noticed the cardboard templates did not line up properly with the screws so here I applied ink to the back of the screw and then pressed it through the hole so it would mark the tape. I went over the slight markings the screw left with the marker so it would be easier to see.

Now with the screw hole positions marked I then found a drill bit that would fit them and drilled out the screw holes. I did a test fit with one hole drilled just to be sure it was right. It is a tight fit but it will work.

Since the first hole was a bit lower then the markings I used a straight piece of cardboard to draw a line and line up the second hole. It wasn’t quite right with the first line so I had to do a second one.

Using the plastic cut out of the first hole I traced around that to mark the second holes location and center.

I then drilled out the second meters hole which the drill saw then got caught on the inner dividers when it went through.

I then removed the plastic dividers underneath the hole using tin snips and flat wire cutters. It is a better idea to remove all the inner dividers now which I had to do at a later step anyway. If you get the container or something similar to the one linked you won’t have to worry about these inner dividers.

Again ink the backs of the screws of the meter then mark and drill them out.

I applied a new layer as I would have to move this meter down quite a bit and then traced around it very messily while trying to take pictures. Mark the center for the next step.

Now drill out the third meters hole.

I then removed the plastic dividers underneath the hole using tin snips and flat wire cutters. It is a better idea to remove all the inner dividers now which I had to do at a later step anyway. I included a few more pictures of the process in case you were curious.

Ink, mark, and then drill the third meters screw holes and test the fit.

I traced a line from the third meters hole edge down to the bottom and drilled it out and its screws the same way as previous steps.

I was originally just going to leave the rest of the inner dividers and just remove them beneath the holes but they would just get in the way of the wiring stages so you are better to just remove all of them like I did in this step. I used tin snips, and flat wire cutters again. Do this at the beginning or better yet get a container without them, its easy enough to do but its also a bit of a pain.

Now its time to remove the tape and test fit the meters before going to the next steps.

Not pictured, but now drill out holes for the switches and the SAE connectors and put them in. I only used two of the screws with the SAE connectors to stop them from spinning or coming out. Then do a test fit wiring with the SAE connectors, switches, and meters. I also created and attached a wiring diagram of what I did here for you to reference which is easier to follow then the mess of wires everywhere in the pictures. I used alligator clip wires and scrap wires to do another test, this time the sun was out full and the light bulb is much more obviously lit up.

Now strip the wires and then crimp a connector onto the SAE connectors wires on top. I did male connectors on both sides so they could not be connected together accidentally. The switch wire was a much lower gauge and I had to use a larger connector for the other wire so I stripped off an extra amount and then folded it in half and twisted it together. I then folded it in half again and twisted it so the connector would fit and crimped a female one on.

This step is very important to avoid accidentally wiring it back together wrong, wasting connectors and wires, or burning out the meters. Now one wire at a time disconnect one alligator clipped wire, replace it with the final crimped wire, and label it before going onto the next wire. This way you won’t get confused and know it will work on the next step. Also mark the meters, and the SAE connectors with which wire numbers connect into them on both sides. I just used masking tape folded over the wire then cut it down to size. I went with this format SAE Connector# “+ or –“ Wire#. Seen in the picture you can see 2 – 1. This way I can look at it and quickly know that this wire is connected to SAE Connector #2, it is a negative current, and that this is wire #1 on this SAE Connector. If you are wonder the main reason I marked the positives and negatives is because the SAE connectors colors and switches do NOT line up with the standard that red is positive and black is negative. I could have made them the correct colors but then I needed a SAE polarity adapter outside on all 3 connectors which makes it bulky and not fit flush. Since this is the case its very important to mark if its positive or negative so you don’t accidentally forget down the road if any maintenance is needed on the inside. These labels will be a life saver in a later step so do not skip this one. I did not fully tighten everything as I will be removing them all later on.

Now that all the final wires are inside and connected to a test and make sure everything is working properly.

Here are multiple pictures of the finished labeled wires so it should be easier to see whats going on. The last few have the solar panels and light bulb removed so it is just the wiring on the inside being seen. The labeling step is a must if you want to make the box look significantly better then just a clear plastic case as we will do next.

Now to give it a very nice appearance you will need a veneer. I liked the look of mahogany wood so I went with that. This is a self-adhesive film veneer so cut out a piece to the rough size. It will be trimmed down to the actual size in the next step.

Now using some 70% or higher rubbing alcohol thoroughly clean the outside and back side of the front on the inside. This easily removes all the permanent marker, hand marks, and any dirt or grime so the veneer will adhere well. Now you can just lay the veneer over it backwards and use the grid on the inside to be able to cut it down to size. Then start by peeling just one corner slightly then carefully place it down on the inside of the lip of the container. I used an old gift card as a squeegee to press it down and remove air bubbles. Then just peel a little bit at a time and press it into place thoroughly before peeling more. It doesn’t have to line up perfectly with the lip on the border as this part will be hidden later on. It folded up a bit and damaged it around the holes of the meters but this part will be hidden by the meter itself so it doesn’t matter.

Now I cut the holes for the meters by first cutting it into fourths then into eights or a + into a *. Then from the outside push in one of slices at a time and press it down onto the inside which will make a sun shape. Then cut a plus into the switch holes and press them inside as well.

Now from the back I used the tip of the same ¾ spade drill bit that was used to cut the switch and SAE connector holes. I just poked it through and twisted it and that cleared the screw holes. They were easier to see from the back and will be hidden anyway with the meter attached so I didn’t worry if this one looked rough on the front side.

With the mahogany wood veneer in place we can put the meters and switches back in and redo the wiring. It already is looking much better then the original plastic container. This is the step where you will be glad you labeled all the wires. It only took me a few minutes to reattach with the labels vs half an hour or more.

Now using some copper tape I cut it out to a bit longer then the box and folded it in half down the center. I then cut along this line so I would have both sides. I then started in one corner with the inside edge that covers the edge of the mahogany wood veneer. I pressed it into the lip with the old gift card down the whole length of the front. I then pressed it into the bottom lip and folded it over the edge using the gift card edge again to press it down nicely on both sides of the lip. Its easier to peel and place it loosely over it like the later pictures and then press it in with the gift card, make sure the better edge of the tape you didn’t cut faces inwards and the cut end outwards to be rolled around the sides where it won’t be as visible. Carefully try to remove any air bubbles with the gift card and make it smooth. This tape is pretty fragile and easy to break but looks really nice. For the corners where it overhangs I cut it with scissors then pressed one half down and then the other over it.

Here are multiple pictures from various angles of the finished steampunk style solar combiner box. The copper and wood even if fake makes it look significantly better. This project is both functional and looks good and I highly recommend taking the extra time to make it more pleasant to look at!

Now with the outside done its time to finish the inside by tightening all the screw that hold down the wiring. Here are pictures after I tightened everything.

A little bit of final testing to make sure the meters show the correct voltage from the solar panels before moving on to the rest of this project.

Now cut off one end of the SAE switched extension cable and strip the ends so we can plug them into a solar charge controller.

Now plug the ends of the SAE extension cable into the solar charge controller and tighten them down. If you are curious the solar charge controller I used I used the 20A EPEVER MPPT Solar Charge Controller. Here is a link to the 30A complete kit since the 20A I ordered seems to be no longer available. You have to have the external screen or computer cable to program these to work with lithium batteries.

Attach the external screen for the solar charge controller so we can adjust settings which is required to set it for lithium.

Crimp connectors on the wires that will go from the solar charge controller to the battery.

With this MPPT charge controller it requires the battery be plugged in before the solar panels or it may destroy something inside of it. Here is a sealed lead acid 12v battery pulled from a dead Uninterruptible Power Supply (UPS) connected and the screens all coming on. This battery is just for initial testing it will be upgraded in the near future to a 100Ah Capacity LiFePO4 Lithium Iron Phosphate 12v Battery that I made using new cells that came in a nice kit that use to be for sell. If there is enough interest I may do a project on that in the future, especially if that kit becomes available for sell again.

Now with the MPPT charge controller connected to a battery the steampunk solar charge controller gets plugged in to test it out. It does all seem to be working and is charging the battery though be it very slowly as this wasn’t finished till way after peak sunlight. The output is terrible at the time these were taken, it is much better during actual peak sunlight.

Now the project is completed and connected to the MPPT charge controller and charging the battery. Here are pictures of the finished steampunk solar combiner that has the input from two 100w HQST panels on the roof that come in end in SAE connectors that I attached. They then get combined inside this box in series which combines the voltages and should give more usable power out of the MPPT charge controller then combining in parallel would. From there it charges a small sealed lead acid battery taken from a broken Uninterruptible Power Supply (UPS). It has no capacity markings but its probably 12Ah or less. To use power I can then connect it either through the load line of the charge controller or directly to the battery. For an inverter to turn it into 120v AC it is usually recommended to connect it directly to the battery. The whole project will be wall mounted by just drilling 2 holes into the back plastic and then putting washers and a screw into the wall.

This also ties into my project called "Solar Energy Flowing Cables".

Here are some upgrade ideas:

• This also ties into my project called "Solar Energy Flowing Cables".
• All in One Box – One upgrade which would be great if I wanted this to be more portable would be to combine everything into a single box so the solar combiner, charge controller, battery, inverter, 5v USB ports, and 12v sockets. This would be an awesome project especially with a more steampunk retro look to it. If I could afford it I would definitely try this.
• USB Ports – It would be nice to have USB Charger ports that run directly off the solar panels not the battery so anything USB could be charged directly through the solar.
• Switch From Series to Parallel – It would be a lot more complicated but it would be nice to have a switch so it can be changed from series or parallel on demand. If set in parallel they could directly charge a Jackery 240 which can support the combined Amps of the panels but not the combined Voltages.
• Internet Connected Status Page – It would be interesting to make it so the device hosts a simple webserver so I could connect to it on most devices and see the live status of the individual panels input, the combined voltage, and the current usage. It could also have a daily graph so I could see the power available and the amount of hours of enough sunlight to power them. This would be a much more complicated project to accomplish but would be very interesting.
• Embedded Battery Charger – It would be interesting to have a battery charger connected inside that could directly charge some type of battery such as 18650 Size Lithium Ion Charger to charge them also directly from the sun.
• Solar Mini Webserver – Combining this completed project as is with a raspberry pi it could easily make a solar powered website that would stay online possibly all night with this battery.

If you would like to support me in making these projects you can do so here.

Do you have any more suggestions? I will add good ones to this list and if there is enough demand I will possibly do some of these ideas in the future.