Grid Down Solar Backup Power for Emergency Communications

Project Start (20 June 2016)

Back in June 2016, I received 2x 40 watt solar panels for testing and review. Well we’re going to throw these panels Straight Into the Fire using them in an off-grid solar ham shack project for emergency communications.

80 watt solar array for grid down Emergency Communications
80 watt solar array for grid down Emergency Communications

Off grid power for emergency communications is a serious topic. For the survivalist, the ability to get news and information despite a grid down scenario, will improve his/her chances of making an informed decision about safety. For radio operators participating in a grid down emergency communications scenario, their ability to keep their stations operational, despite the blackout in the outside world, quite simply, might save lives!

One important thing about this project is, solar power systems don’t need to be large or costly. In fact, this system could very easily be deployed on an apartment balcony, or the side of your garage. The difference between storing gasoline for a generator, or a small solar power system to charge “critical” components, and communications during a black out is a ni-brainer. We are not trying 9to power our large screen TV. We are trying to keep communications and critical gear operational.

Shack Equipment

My ham shack has three modes of operation.

  • Idle:  in this mode I’m sending out WSPR beacons. Equipment used can be Yaesu ft-817, or Youkits TJ2B, WolphiLink interface, with either an Asus Eee pc or HTC Nexus 9. Also on occasion I run an HF APRS igate on 30 meters.
  • Active: in active mode I’m usly using the Yaesu ft-817, or other HF radio for voice or digital Communications using the WolphiLink interface, with either an Asus Eee pc or Nexus 9. I’m also using a strip of DC LED lights.
  • EMCOMM: in this mode on using the Yaesu ft-817nd, with a 50 watt amplifier, the Asus Eee pc, running FLDigi. There’s also a strip of DC LED lights, and battery powered noise cancelling headset microphone. This mode requires the highest sustained amperage for operation.

Cost breakdown

Total price 195$

The panels

2x 40 watt solar panels
2x 40 watt solar panels

The two panels are budget models (Energy+ SY-M40W Google it) re-branded and sold by a local supplier. Build quality seems fine, with both panels having full aluminum frames built around them to facilitate frame mounting.

Each panel is 40 watts and generates ˜2.4A in full sunlight. My plan is to mount then side by side on the tower, using them to maintain a re-purposed 100 amp battery (from the Subaru upgrade) used as backup power for my radio room.

panel specifications
panel specifications


Electrical connection 27 (June 2016)
Panels are connected in parallel to make an 80 watt array
Panels are connected in parallel to make an 80 watt array

The panels are  in parallel. This will bring potential amperage to around ˜4.8A in full sunlight. This is easily enough to run my HF radio, charge my tablet, and power a moderate DC or USB LED lantern. Most importantly, its enough to keep the charge controller happily topping up the battery, (year round?). Fault tolerance is also better when you wire these systems are parallel. If for some reason one of the panels is damaged it doesn’t affect the operation of the other.  Please remember when wiring in parallel to ensure that both panels can receive about the same level of sunlight. Amperage between two parallel panels will be averaged between the higher and lower amounts reducing the performance of the array overall. 

Tower mounting

To mount the array on the tower, we’ve fabricated a rack. Since this was an unplanned project and to keep costs down we decided on a fixed elevation rack, which would attach easily to one of the three Tower legs, using U-boats. The picture immediately below this text is the first prototype. It’s made from metal junk, re-using things that would have gone to the landfill anyway.

Panel elevation

One of the channel contributors asked about the fixed elevation of the rack. This is how I answered.  Right now we’ve got nearly 24 hours of daylight. November-January, we’ve got only a few hours of sunlight. Outside those months, we have normal days. Considering this was an unplanned project, we’ve got to start someplace. The elevation and their height on the tower, is set to ensure the panel’s get “at least some” hours of direct sunlight everyday, all year round. It’s not perfect but it’s a starting point.

Prototype solar array rack for tower mounting
Prototype solar array rack for tower mounting

Jumping ahead, this next image is what the panels look like on the tower.

Tower mounted solar array
Tower mounted solar array

The panels are tower mounted out of harms way and toward the south-southwest sky, giving clear view to the sky. Mounting was done using a homebrew frame, attache to a tower leg at two points.

Frame (28 June 2016)

Rack is completed and panels are mounted.
Rack is completed and panels are mounted.

Today we finished welding up the rack. Quick hit with a sandblaster and a couple of coats sealer and paint before mounting the panels to the rack. This is what they look like.

Panels mounted, racked completed, ready for tower.
Panels mounted, racked completed, ready for tower.

Tower Installation (29 June 2016)


Today  we installed the solar array on the tower. Installation went well, with no broken panels, or injuries (dropped tools). Next time we’re going to wire up the battery and charge controller. When all of this is done I’ll publish a video on YouTube about the project.

Charge controller options

One of my buddies posted today about a problem he was having with the product not regulating the voltage correctly for his devices. This loose connection to my own project reminds me of the importance of choosing the right charge controller. I don’t know if or when I’ll ever be able to add additional panels to this array, but it’s certainly something that I want to do. So for the interim I’m going to be using an old charge controller that I’ve had for a while. It’s the charge controller from my 7 days off grid with a 13 watt solar series. I’ll use that one until I come up with the correct charge controller for this project as well as the Project’s future needs.

Morningstar Sunsaver 10L (06 July 2016)
OH8STN Morningstar Sunsaver 10L charge controller
OH8STN Morningstar Sunsaver 10L charge controller

In the end I decided on the Morningstar Sunsaver 10L charge controller. This will allow me to add two more panels without the need for an additional charge controller. It can handle 30V panels up to 10A, charge the battery at 10A, and sustain a 10A load. All my panels are in parallel (22v open voltage), so there is a lot of room to spare.

The Charge controller will have to deal with the 80 watts string, up on the tower now. It will also have to deal with the 100A battery. It will also have to carry the “load” of my two radios, the Yaesu FT-817ND, Kenwood TMD700, finally my Asus EEEpc or Nexus 9 tablet.

Radio Noise

The Sunsaver 10L has two charging modes which are interesting for radio operators. PWM is its standard charging mode. This mode is the cause of lots of the radio noise found in solar systems, and a serious pain in the butt for radio operators on HF.  Thankfully the Sunsaver 10L hads a second charging mode called Slow Switching Regulation. Slow Switching regulation limits the switching frequency to 10hz, which can eliminate the noise generated by PWM charging. We are certainly going to test the two modes.

I have to tell you I’ve had problems sourcing the Morningstar here in Scandinavia.  I suppose I expected sourcing the Morningstsr to be as easy as the Genasun, who make it incredibly simple to buy their products online.  I’ll keep you guys updated.

Genasun for future upgrade?

Future plans include 4 strings of panels. Two strings on the east and two strings in the South-Southwest. Each string will have its own MPPT charge controller. Perhaps those will be Genasun charge controllers. Which ever brand they’llk b, they will allow me to take advantage of morning and afternoon sun without dragging down the output of the other strings. More on this when we are closer to that (Spring 2017).


Radio Noise from panels & controllers

One of the mistakes many radio operators make, is with their selection of charge controller. Noise from the DC/DC converters is hell on HF communications. For this reason we employ a noise free charge controller, for the all important weak signal work.

CirKits SCC3
CirKits SCC-3 20A Charge Controller
CirKits SCC-3 20A Charge Controller

One of the regular contributors to the channel mentioned building and using this kit.  It’s also completely radio quiet! Once again there’s the lack of a regulated load port. Considering how difficult it is to find locally the Morningstar controller, maybe I’ll just have to bite the bullet and build the regulated port for either this charge controller or the previous one.

The SCC3 is suitable for stationary and portable solar power systems. It is an excellent choice for emergency backup and stand-alone building power systems. The SCC3 is also perfect for recreational vehicle solar power systems. Combine the SCC3 with a solar panel and rechargeable battery for a reliable source of DC power that’s available, even when the power company is not.

Controls and indicators include a battery float voltage adjustment, a battery equalize (overcharge) switch and a red/green Charge/Float LED.

Future plans

If the funding ever presents itself, these pictures show in detail the plans I have for the system.  So I would like to replicate the first string. 2 40 watts panels in parallel, to their  own mppt charge controller, replicated 4x.

I’m no Picasso!

Future expansion
Future expansion

As you already know, my channel has a big boot in emergency communications and preparedness. Experimentation with off grid power solutions for emcomm or disaster communications is a serious topic, and one that most in the emcomm or survival communities will come to sooner or later.

Build video is coming up soon.

SurvivalTech Nord