Solar Tracker, self powered and auto aligning

2-Axis solar tracker interfaces to a power monitor and charger/inverter

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I'm building a house in the mountains of Aragon in Spain on an old, 120 acre olive farm. There are no mains services , electricity or water, but we have got high speed long range Wimax Internet and a borehole. To maximise power year round, I need a solar tracking system.

I've designed a solar powered, wifi linked controller that can talk to an MQTT server. Also I have a power monitor for each set of panels that also communicates with the charger/inverter. The tracker uses a cheap GPS module to get time, latitude and longitude so it needs very little setup. I've also designed a weather station so the panels can be layed flat if the wind gets too high to avoid damage in gales.

You simply put in the panel sweep angles on a setup web page and off it goes..max power all year round, cheaply.


I need quite a few solar panel sun trackers to generate as much power as possible from 60 solar panels. 

Why? well, we bought a farm in Spain, 120 acres of olive tree garnished paradise.

I'm building a large, off-grid property to replace a derelict farmhouse which is in the mountains of Aragon ...sounds like somewhere out of Lord of The Rings and if I look carefully, I'm sure that I can see Mount Doom somewhere in the Maztrazgo mountains...

Of course, I'm going to need power, lots of it. 

I searched the market for a cheap solar tracking unit as my tests in Spain over the last year led me to realise that I need to optimise the amount of power available, especially in the winter. A tracking system will optimise the sun power that I can use and extend the times of day when maximum power is available.

In the area of Matarranya where I'm building (see, there are a number of other off-gridders dotted around, however, they generally use gas or oil for heating and cooking plus around a dozen solar panels for basic electrical requirements. They end up running their generators for much of the winter and that goes against my principle of no carbon based fuel brought to the land. Carbon-based wine is a different matter, however. That is allowed by the truck load.

My guiding light is that I want my house to be really, properly and totally self sufficient - i.e. all electric, powered by a combination of solar and some wind. Basically, I want to be different. Also, I don't want to have to haul off into town which is 10 miles away down a dirt track just because I run out of cooking or heating gas.

In the summer, folk just put up with the heat as they generally don't have enough power for aircon. However, I'm going to use reversible air source heat pumps with under floor piping to heat the house in winter and cool it in summer. This means that the concrete floors become a thermal battery and I can either put heat into the floors ar remove it during the day when power is plentiful and cut it off at night to avoid battery drain. A huge hot water tank also run off a separate air source heat pump will be another thermal battery - additionally, a pair of immersion heaters will allow me to heat the water to around 85 degrees celcius (185 fahrenheit) whenever there's spare power. I'll also automatically switch on the charging power to my Tesla if there's any power left over - see, I don't even need fuel for the car...admit it, you were wondering if I was actually a hypocrite with a planet destroying gas guzzler. My son calls it "electric smugness" and, apparently, I have it in spades. Can't see it myself though.

Tests have been done  with a neighbour who has now finished his house. Last winter he kept his house at a steady 22 degrees celcius (72F) and ran his electrics all winter from 15 x 260W panels. Obviously, 6 inches of insulation in the walls and floors helps. However, once the house has attained the correct temperature, it doesn't need much input.


My early trials just used a single axis tracking system. The first video shows the first tests in my workshop. There's also a bit of a tour of the 8-channel solar power monitor and mains inverter interface if you're interested.

The finished prototype

My solar tracking metalwork is fairly simple. It uses  eight cheap, stainless steel ball bearing hinges, some steel and two 4 inch (100mm) linear actuators. The initial prototype was in aluminium, but it's such a pain to weld, that I have moved to mild steel. You don't actually have to weld it together as you can just use...

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Solar Power Monitor Interconnections.pdf

This shows how the Solar Power monitor/inverter interface connects with the 8 way current monitor, the solar arrays and the MPPSolar PIP4048 inverter/charger

Adobe Portable Document Format - 437.92 kB - 07/15/2018 at 16:24



Solar Power Monitor Arduino Files. This uses the Arduino ATMEGA1284 library. This version has pre-programmed MPPSOLAR and network values as the standard Arduino webservers don't work withe ATMEGA1284. I am working on a full webserver for this to allow programmable parameters. This version needs the parameters to be set at the header of the program and then re-compiled

plain - 27.53 kB - 07/15/2018 at 15:54


PIP4048 Monitor-W5500.BOM

Solar Power Monitor and interface to the MPPSolar PIP4048 offgrid inverter - parts list

bom - 14.30 kB - 07/15/2018 at 15:52


PIP4048 Monitor Schematic.png

Solar Power Monitor and interface to the MPPSolar PIP4048 offgrid inverter - schematic diagram

Portable Network Graphics (PNG) - 240.51 kB - 07/15/2018 at 15:52


PIP4048 Monitor PCB Layout.png

Solar Power Monitor and interface to the MPPSolar PIP4048 offgrid inverter - PCB Layout

Portable Network Graphics (PNG) - 118.67 kB - 07/15/2018 at 15:52


View all 22 files

  • 1 × PCB Reference "SOLAR TRACKER V2.3" ESP8266 based solar panel tracking controller - see FILES section for PCB files and BOM (Bill Of Materials) for components used
  • 1 × PCB Reference "Liion Backup V2.3" Solar powered Li-ion battery charger and power supply unit - see FILES section for BOM
  • 2 × 100mm Linear Actuator 750N, 100MM, 12V linear actuator from Ebay etc
  • 3 × 50mm (2") steel or aluminium box section 3mm thickness or greater x 2m (6ft) length for ground post + 1.5m (5ft) for rotator unit + 3m(10') for elevator bar
  • 1 × 50mm (2") steel or aluminium flat bar 5mm thickness x 3m (10ft) for elevator bar

View all 10 components

  • Dampers

    aidan ruff07/28/2018 at 19:08 0 comments

    Whilst addressing the problem of the azimuth attachment bolt coming loose, I've also decided that I need some form of damping in higher winds.

    Fortunately, I've got a range of the hydraulic lift arms which I bought in the earlier experiments. Once the weather improves, I'm going to attach a couple of 10KG force lift arms to both axes of the solar array and see if that helps reduc rattling in high winds. I think that it was the rattling that managed to loosen the attachment bolt, so some damping should help.

    I'll update once I've tried it ouit

  • Linear Actuator Attachment

    aidan ruff07/28/2018 at 19:02 0 comments

    We've had some very high winds here in Northumberland due to the thunder storms that have been hitting us. So, the azimuth linear actuator attachment that swings the array horizontally has managed to work it's way loose and the array is swinging around rather alarmingly.

    I've come up with a solution which is to replace the attachment bolt fixing which was just a nut and a locking washer with a nylon captcher nut and it seems to be a lot firmer. I think that the attachment brackets that come with the linear actuators probably need changing as well as they don't have a ball bearing attachement, just a simple pin and hole arrangement.

  • Introduction Video

    aidan ruff07/15/2018 at 19:04 0 comments

    Today, I managed to get time to to an introduction video for the solar power harvesting project.

    you can see it on youtube here... Intro Video

  • Three Solar Panels Mounted Onto The Tracker

    aidan ruff07/15/2018 at 14:17 0 comments

    After a very busy few weeks, I successfully got 3 solar panels mounted onto the tracking platform...more's the point, the whole rig survived some pretty strong gales

View all 4 project logs

  • 1
    Step 1

    General Details for the Tracker Frame Assembly

    The solar panel frame is built in three sections:-

    1. The Ground Post. This is a 6 feet length of 2" steel or aluminium. If your local weather tends to be a bit stormy, you might consider incerasing this to a 4" post for added stability. Take 3 of the 4 inch hinges and mark out their positions as per the drawing in the FILES section - basically , you will need around 3 to 4 feet of post buried in the ground, so space the 3 hinges one o the top of the post, one just above ground level and one in the middle. Mark the hole centres for the hinge mounting holes and drill all the way through the post. Take the 3 inch stainless steel M4, countersunk bolts and push them one at a time through the hinges and the post and secure them on the other side of the post using M5, locking stainless steel nylon locking nuts. Repeat for all three hinges.
    2. Pre-Make the rotator head. Follow the drawing in the FILES section and either weld or bolt a length of 2" steel or aluminium angle to the length of 2" post. Weld or bolt 2 stiffening struts to secure the 2" angle.
    3. Take the 10 ft length of 2" steel/aluminium box section and marry it up with the rotator head angle section that you've made above in section (2) then mark out and drill the mounting holes through both sections. It's best to clamp the two together to make sure that all of the holes end up lining up.
    4. Hammer or bury the ground post into the ground in the position that you want your panels to be. Ensure that it goes in vertically by using a spirit level. Make sure that post is align to true North/South - just use Google Earth to pick a spot that lies on the line to true South from your solar panel position. The hinge holes that pre-drilled to hold the rotator head should be pointing due West - that's true west, not magnetic west. If Your pole is properly aligned, then this will already be the case. The software will compensate for your alignment not being perfect, but the more accurately it is set, the better.
    5. The rotator assembly. Attach the rotator head to the ground post with the hinges that you've already attached - mark out the hinge mounting holes and drill through the rotator 2 inch box section, then use 75mm countersunk stainless bolts + nuts to tightly secure it to the ground post. You now have a rotatable mounting for the elevation bar.
    6. Use some 1 inch (25mm) stainless steel, countersunk head bolts to attach 5 of your 4 inch stainless steel hinges to the elevator bar - this is the 10 ft length of 2 inch aluminium/steel flat bar. The hinges are evenly spaced along the length. Drill the matching hinge holes on the main rotator bar (the 10'/3m length of 2"/50mm holow section)  and attach the elevator bar using the hinges that you just attached. You should now have a 10'/3m , hinged elevator bar.
    7. Attach the linear actuator mounting brackets and linear actuators as per the drawings - don't forget to put on the rubber gaiters to cover the linear actuator extension arms for weather protection. 
    8. Attach the elevator bar to the rotator head that you attached to the ground post above and you now have a solar tracking array capable of rotating 3 solar panels to track the sun
  • 2
    Hanging The Solar Panels

    Ideally, the solar panels need to hang on the tracking array so that they have a neutral weight on the elevation adjustment hinges. So, I have made some simple hooks out of some of the offcuts of flat, 2" bar used to make the elevator bar and the rotator head stiffening struts.

    Cut two x 2 inch lengths of metal and 2 x 4 inch lenthgs. The short length is just a spacer and the long length is the hook. Mark the back of your solar panel so that when it is hung onto the elevator bar, it's centre of gravity (i.e. the mid-point) is aligned with the elevator bar hinges. Carefully pre-drill holes through the two x 2 inch bars into the aluminium frame of each solar panel and secure with 25mm/1" stainless steel bolts. 

    I found it re-assuring to put  abit of metal bar under the solar panel drame that I was drilling to protect the solar panel as I had nightmares about drilling through and damaging the glass bit of the panel and thereby rendering it pretty useless.

    There's a drawing of this in the files section

    Hang the first panel centrally on the elevator bar and then drill an attachment hole through the stiffening frame and into the aluminium frame of the solar panel and attache the two with a 25mm/1" bolt.

  • 3
    Solar Tracker Electronics

    In the FILES section, you will find all of the files necessary to sendoff to a PCB manufacturer. I have been using for about 18 months and they have a fast, reliable service. Order both the the controll PCB and the charger/power supply PCB at the same time and you will get them both delivered in about a week using DHL delivery for around $35.

    Just start an order and upload both ZIPPED sets of GERBER files and the PCB manufacturer will do the rest.

    GPS RECEIVER. You can either use the cheapie ($1.50) version or the more expensive $5 version which I used. For 5 bucks, you get a more sensitive receiver with a larger antenna, which may help if you have geography blockin the satellite signals in your area.

    IN the picture above, you can see how the two PCBs are interconnected. There are three motor control outputs - I was originally only going to use elevation control, so the unit would control three linear actuators. However, adding the azimuth control to track the sun horizontally as well as vertically, only requires 2 of the outputs.

    The two boards can be joined using PCB mounting posts if you want. The connections will then line up so that you can interconnect the power from the charger/Power supply to the tracking control PCB.

    I've used 2 18650 li-ion batteries which claim to be 4800maH, however, after checking them on a power monitor it  turns out that they are actually only 2000maH. This is common on low cost li-ion available on Ebay...they're just re-packaged, low cost batteries sold at a higher price, so be careful. On the other hand, you only need about 500maH fully charged to run the electronics overnight, so cheapie batteries are in fact fine.

View all 4 instructions

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aidan ruff wrote 07/15/2018 at 13:24 point

That's a really good point! I've added the Arduino code to the files section. Bear in mind that this runs on an ESP8266 so you'll need to add that processor to your environment...really easy. 

The list of libraries are in the <include> section at the beginning of the code file

  Are you sure? yes | no

jonsargeant wrote 06/18/2018 at 20:27 point

I'm with John :) A very interesting project that has a lot of obvious expertise behind it - I'd love to see the code as well.

  Are you sure? yes | no

John wrote 06/18/2018 at 11:42 point


    Where did you stash the code?  I can't see it in the files section.

   Glad to see that you're both fully qualified water diviners now.  Interesting  effect, isn't it? 


  Are you sure? yes | no

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