DIY: The Off Grid Ham 100 Watts For $300 Solar Energy Plant

I am frequently approached by frustrated radio amateurs who are looking to get into solar power and feel completely lost in all the options. To address the need, I’ve come up with a simple solution that really works and is priced right. I call it The Off Grid Ham 100 Watts for $300 Solar Energy Plant. If you need inexpensive solar power for amateur radio and/or prepping and don’t know where to start, then you’ve landed on the right web page.

Almost all of the ready made kit systems are overpriced and under powered. I came up with this idea to help hams who have money to spend but not money to waste. In a future article, I will talk more about why I don’t like kit systems such as this one or this one.

A few caveats.
Because it uses a pulse width modulation (PWM) controller, the Off Grid Ham 100 Watts for $300 Solar Energy Plant will top out around 80-85 watts maximum output from the solar panel. If you read my recent article about solar charge controllers, you already know that PWM controllers are less efficient than MPPT versions, but cost a lot less money. That is one of the compromises here. To bump up the output, you can add panels (or use a bigger single panel) as long as you do not exceed the 10 amp limit of the controller.

This do it yourself project will easily power your handy talkies, other electronics, a VHF/UHF mobile radio, a few lights at night, etc.; and with conservative use of the transmitter, run a higher powered radio. The goal of this solar energy plant is not to address every possible need, but to offer radio amateurs with a real alternative to overpriced, underperforming commercially made kits. If you have never worked with solar energy, this is a perfect starter system you can make yourself, learn on, and will not quickly outgrow.

What you need to know: The Off Grid Ham 100 Watts for $300 Solar Energy Plant will produce reliable power but is a no frills affair. I’ve carefully edited the parts list down to the bare minimum needed to meet the $300 price point while still giving you something genuinely useful. Add or change anything you want, but the more fluff you tack on, the farther the project gets from its original intent of being inexpensive and simple.

Parts List.
All these items were selected for their “bang for the buck” factor, low cost, and long term reliability.

Morningstar 10 amp PWM controller: $48.00 from Northern Arizona Wind & Sun.
Power-Sonic 26 amp-hour SLA battery: $59.00 from Battery Junction
Renogy 100 watt solar panel: $129.00 from Amazon
20 foot MC4 cable: $15.00 from Amazon
Assorted wire, connectors, hardware, taxes, shipping fees: $49.00

TOTAL= $300.00

MC4 Connectors.
The Renogy solar panel has MC4 connectors, which are an industry standard and designed for permanent outdoor use.

What you need to know: These connectors require a special tool to disconnect them once they are plugged in. Sometimes you can disconnect MC4’s by hand, but it’s difficult. I suggest spending an extra five bucks and getting the tool. Do not cut off, change, or alter the connectors on the panel.

mc4 connector

Male and female MC4 connectors on the back of the solar panel. Do not cut or alter these connectors. Off grid Ham original photo ©2016

Note: I’m including these detailed instructions for those who are inexperienced with renewable energy. If you are a “been there, done that” type, you can skip this section.

Assemble The Off Grid Ham 100 watts for $300 Solar Energy Plant in an area where the panel is not exposed to direct sunlight.

Cut the 20 foot MC4 cable in half so that you have two, ten foot cables: One with a male connector and one with a female. Crimp a spade lug on each bare end; you may also want to use Power Poles or other DC connectors for flexibility. Connect the cables and the battery to the solar controller on the terminals indicated, paying attention to polarity. Do not connect the cables to the panel yet.

Be sure to include a fuse on the positive wire as close to the battery as possible. The fuse does not need to be anything special…a simple in line 10 amp fuse holder from an auto parts store is fine. Also, it’s easier and neater if you mount the controller on a board or other hard surface.

solar energy


solar charge controller wiring example

Morningstar 10 amp solar controller. The connectors at the bottom of the photo are the MC4’s for the solar panel. The alligator clips in the middle go on the battery. The Power Poles on the upper right connect to the load. Off Grid Ham original photo ©2016

Check the voltage on the battery. It should read 12.45-12.95 volts.

The LOAD terminals connect to the device you are powering. Again, using Power Poles or 12 volt automotive breakaway plugs instead of hard wiring to the terminals makes things easier. You can also power your devices directly from the battery terminals but understand that doing so bypasses the automatic low voltage shut off built into the controller.

Plug the MC4 cables from the controller into the panel and set the panel in bright sunlight. Check the battery voltage again; you should now see over 13.00 volts depending on how sunny it is and the original charge state of the battery. Congratulations; your Off Grid Ham 100 Watts for $300 Solar Energy Plant is on line!

Using Your Solar.
Plug devices into the the 12 volt output as needed, keeping in mind that if the load drains the battery faster than the panel can fill it, you will eventually run the battery dead. It is very helpful to monitor your voltage and have real time awareness of the battery charge state.

In bright sun you can pull over 50 watts and the battery will not run down. That means the panel is meeting all your power needs with no help from the battery. On cloudy days or when you are demanding more power than the panel alone can produce, the battery will discharge to make up the difference.

The Renogy panel and the MC4 connectors are designed to be left outdoors all the time. You do not have to protect them from the weather.

I can take my solar energy setup out in the field and, after an entire day of ham radio operating, still come home with a fully charged battery. If you are using only handheld radios and/or running QRP, you should be able to operate almost indefinitely without ever having to be concerned about the availability of grid-based power or fuel for your gas generator.

Key Points–What You Need To Know.

  • The Off Grid Ham 100 Watts for $300 Solar Energy Plant provides a high “bang for the buck.” You cannot do much better at this price point.
  • A PWM controller is used to keep the cost down. The tradeoff is less efficiency. The panel will have a maximum output of about 80-85 watts.
  • MC4 connectors are an industry standard for solar panels. They require a special tool to disconnect and are designed for continuous outdoor use.
  • You can run a full power (100 watt) HF radio with this setup, but only in strong sunlight and even then keep your duty cycle short so the battery has time to recover in between transmissions.

I understand that money is an issue for many; the Off Grid Ham 100 Watts for $300 Solar Energy Plant is very inexpensive by amateur radio standards and will give you a very high level of independence from commercial power or mechanical generators. It’s an ideal mix of performance and economy that should serve you well for many years.

Disclaimer: I do not sell anything. I do not have a pecuniary interest in the products mentioned in this article nor am I related to anyone who does. The items specified were purchased through normal channels with the author’s personal funds. The author did not receive any monetary compensation, gratuity, or merchandise in exchange for this article.


14 thoughts on “DIY: The Off Grid Ham 100 Watts For $300 Solar Energy Plant

  1. Mike, KEØGZT

    Chris, I find this off-grid solar power source very interesting, and plan to give it a try. I’ll gather necessary components in coming weeks and let you know when it’s assembled and operational. Maybe even do a review. I’ll keep you posted. MH

    1. Chris Warren Post author

      I’m sure you’ll get great results with this project and I would welcome feedback from you or anyone else who gives it a try.

      One of the goals of Off Grid Ham is to present real-world practical ideas that anyone can implement so I hope you’ll stop by again soon.

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  3. WB8ERJ

    Great resource here! A few months ago, I converted my home ham station over to solar / off grid. I too used a 100 watt solar panel, but I used a size 29 deep cycle battery, and was given a second one, which is in parallel with the first one (and yes, we love our fuses!!). This powers my 2 meter, and 70 cm HT type rigs, as well as my Icom IC-745 nicely! Obviously, I am not going portable with this, and that is not my intention.

    I do plan on building a similar system like yours for portable / off-grid scenarios. With that one, I will probably go with a MPPT charge controller though to get a bit more efficiency.

    Keep up the great work! Hope to work you on the air someday!

    — Mike WB8ERJ

    1. Chris Warren Post author

      Hi Mike, I’m glad you found Off Grid Ham. I have two portable solar panel setups, one has a Blue Sky Energy MPPT 25 amp controller (which alone cost more than the $300 budget limit for the entire project in this article) and the other has the Morningstar PWM controller in the photos above. They all have their pros and cons; for portable operation I use the PWM unit the most. Thanks for your comments; I hope you’ll stop by off Grid Ham again and spread the word to your friends.

  4. Mark - W0QL

    Chris, great article and very well researched. I just completed a system to power my remote base before I saw your article and I learned something about interference. I used a Renogy solar controller and it interferes with the low HF bands and the broadcast band (sounds like a motor boat). Upon doing a little research I believe the secret is we want a controller with FCC Class B certification and almost none are. Although the Sunsaver is not certified Morningstar states in the manual it has tested them and they meet Class B specifications. You made a good choice and a good recommendation. Congratulations.

    1. Chris Warren Post author

      Hi Mark, thanks for your comments. While solar equipment can interfere with ham radio, the instances are rare. A recent QST magazine had a cover story about RFI and solar installations. The author never mentioned if he was solving a known problem or was preemptively trying to prevent one. I got the impression that he was putting himself through a lot of trouble and expense to solve a problem I’m not sure he even had in the first place. You obviously were responding to a very real issue and I’m glad it worked out for you. My advice to other hams is not to worry about a problem until you actually have one. Thanks again for stopping by Off Grid Ham, Mark. I hope you’ll come back again and bring some friends with you.

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    1. Chris Warren Post author

      I have not heard of amy of the brands mentioned but they appear to be solid products. It does somewhat concern me that most of the product descriptions are very sparse and leave out a lot of technical information. For example, no where in the product description for the Canadian Solar CS6P-260M does it mention what the wattage of the panel actually is. We can infer it is 260 watts from the product name, but how can anyone know for sure? It is considered standard for sellers of solar panels to mention basic specifications or at least include a link to the manufacturer’s data sheet. To not do so is at best negligent; at worst, covering up a scam. As a consumer you need to independently verify facts and not assume anything.

      That said, they are priced at less than $1/watt, which is unheard of when buying single panels. The last caveat to look out for is shipping charges. Panels of this size are too big to sent as standard packages and must be shipped as either freight or oversized packages. That of course involves higher charges. I placed a dummy order just to see what it would cost and it turns out shipping one Canadian Solar CS6P-260M to my home would run nearly $150.00. That adds more than 50% to the bottom line and certainly goes a long way in wiping out the benefit of that sweet sub dollar-per-watt list pice. All of the solar panels in my systems are less than 150 watts because that’s the largest panel that can be sent via standard ground shipping.

      I hope this information has been helpful. Thanks for stopping by Off Grid Ham. I hope you’ll come back again soon and bring some friends with you!

  6. David

    Thanks for a very informative and useful article. Your suggested components list includes a Morningstar Sunsaver 10 amp PWM controller (SS-10-12V). For a few more dollars there is a version of this controller with a low voltage disconnect (LVD) function (SS-10L-12V). Given that standard 12 volt batteries don’t typically tolerate deep discharge very well, do you think this additional function would be beneficial?

    1. Chris Warren Post author

      Hi David, When I originally posted this article the controller included a low voltage disconnect (LVD). It looks like since then, Morningstar has reconfigured its product line to make the LVD an option. I say yes, spend a few extra bucks and get the LVD option. It’s not a must-have, but is a low cost way to protect your battery, especially if you do not have any other way to monitor the voltage and/or if the system will run unattended for long periods. Thanks for catching this detail. I’m glad you benefitted from this article and hope you’ll stop by Off Grid Ham again soon.

  7. Dave

    What gauge wire did you use on the solar control to the panel, battery, Load?? I have the 20 Amp controller and plan to use two 100 watt panels and a 75 amp hour battery for field use. Right now I have only one panel.

    1. Chris Warren Post author

      From the panel to the controller I used 10 gauge solar panel wire because that is the standard and it’s also what works best with the MC4 connectors. That’s kind of overkill, though. One 100 watt panel does not produce enough current to mandate that large of a wire. Two 100 watt panels together will go to about 11-12 amps. Unless you plan on a very long wire run, 12 gauge stranded wire should be plenty good enough. The same would apply for the wire between the controller and the battery. As for what wire to use to the load…well that depends on how much of a load you are taking from the battery. The average portable ham gear does not pull more than a few amps. I usually use the stock power cord that came with the radio. I hope this info is helpful. Thanks for stopping by Off Grid Ham. I hope you’ll come back again.


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