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The primary form of heating in our home is a wood burning stove. You’re probably thinking that this isn’t very ‘smart’ and you’d be right. It’s the least smart part of my smarthome, requiring daily lighting and monitoring during the winter months. What it is though is eco-friendy and cheap to run. Also, nothing quite beats a wood fire for warmth and hygge. The point of all this is that we have a wood shed (two actually) at the back of our house. During dark winter nights, trips to these have been fraught with danger and mystery due to a lack of lighting. That is until now: this winter my completely over-engineered, ESP32 driven, solar powered, smart LED lights will light the way!

Of course, I could just use a head torch for my after dark trips to the wood shed. Or buy any number of (doubtless cheap and nasty) solar powered lights from the local DIY store. However, that didn’t seem very fun and wouldn’t integrate with Home Assistant and the rest of my smarthome.

Components

For these lights I decided to use WS2812B light strip driven by an ESP32. The solar power system would utilise an off the shelf solar controller and lead acid battery along with a 5W solar panel which I acquired cheap from work.

Full Parts List

The specs of the solar panel

GCode for the Ender 3 is also available for the 3D printed parts. If you have another printer you’ll need to slice the STL files yourself. I had a few issues with some of the small brackets adhering to the bed, but I was able to get a high enough yield thanks to the OctoPrint-Cancelobject plugin.

The LED brackets

The battery bracket

The charge controller is rather over-spec’d for the LEDs I’m actually running (which pull less than 2A at the 12V battery voltage, on full brightness). This is because I originally thought I would use the full 5m of LED strip that I ordered. However when it arrived and I saw how bright they are I downgraded to just 2m. I had also ordered a beefier power supply for this purpose. The one I ended up using was left over from my failed tablet salvaging efforts. This means I have 3m of LED strip and a decent power supply left over for a future project.

Putting it Together

I spent the better part of a day putting together the components and soldering all the cabling. I then spent at least another day mounting things on the shed and fixing issues. All the joins between cables are double covered with heatshrink tubing. The first layer insulates the cable from any neighbouring cables. The second layer is for waterproofing and has roof sealant injected into it. The same is done on the joins between the cable and the LED strip. Hopefully this will stand up to the intense New Zealand rain. Seriously, you have not seen rain until you’ve seen NZ rain! Luckily most of the components are mounted out of the worst of the weather. The cables enter the box through the IP68 cable gland which should be weather tight.

Mounting the electronics in the case

The battery is held securely with that bracket

Mounting the first LED bracket

The LED strip mounted to the shed

When I tested the LEDs after soldering the lead out wires to them I found that the colours were off and transitions and effects were flickery. This could have been due to either a power issue or an issue on the data line. Measuring the 5V line showed minimal voltage drop there. Since the LEDs were OK before adding the lead out I went with the data issue.

The sacrificial pixel assembly before mounting in the case

The issue turned out to be due to voltage drop on the 3.3V signal from the ESP32 along the lead out cable. The data line is quite sensitive to voltage drop here because the LEDs are supposed to receive a 5V data signal. They work with 3.3V, but not much lower. In order to solve this I added an single extra pixel at the microcontroller end to boost the signal voltage from 3.3V to 5V. This solves the issue since the data signal is being amplified by each pixel in the chain.

ESPHome Code

The ESPHome code to drive the lights is fairly simple. First we start with the standard setup:

--- esphome: name: shed_lights platform: ESP32 board: esp32doit-devkit-v1 wifi: ssid: !secret wifi_ssid2 password: !secret wifi_passwd2 use_address: !secret shed_lights_ip mqtt: broker: !secret mqtt_broker username: !secret mqtt_user password: !secret mqtt_passwd # Enable logging logger: ota: password: !secret ota_passwd

Here we define the board type, set up the wifi and MQTT connections, enable logging and set up OTA updates. If you’re wondering why I’m using MQTT rather than the ESPHome API, it’s for no other reason than I like MQTT!

power_supply: - id: 'led_power' pin: number: GPIO25 inverted: true

Next I set up a power supply component. This is used along with the single channel relay to automatically power up and down the power supply to the LEDs. This will save a bit of power and also makes sure that there is no power flowing in the cables outside the box for most of the time, which may help in the event of a leaky connection. In order to do this I’m not running the ESP32 from the same 5V supply, instead using one of the USB ports from the solar controller.

The LED strip configuration is then pretty standard:

light: - platform: fastled_clockless chipset: WS2812B pin: GPIO23 num_leds: 61 rgb_order: GRB name: "Shed Lights" effects: - addressable_rainbow: - addressable_color_wipe: - addressable_scan: - addressable_twinkle: - addressable_random_twinkle: - addressable_fireworks: - addressable_flicker: power_supply: 'led_power'

Note that there are 61 pixels here, that 2m at 30 pixels per meter plus one sacrificial voltage boosting pixel. The addition of the effects is a bit of a gimmick since I’m mostly interested in white light for the application. I only bought the RGB LEDs because the price difference wasn’t enough to justify only buying white.

The finished electronics mounted to the shed

The solar panel is mounted to the fence behind the shed

The electronics box and panel on the end of the shed

Voltage Sensing and Health Monitoring

After putting all this together and mounting it on the shed I decided that I’d like to have some form of monitoring for the voltages from the battery and solar panel. The solar controller obviously monitors these but there is no way to get this data out.

In the end I soldered up a couple of voltage divider circuits and added these to the setup in the box. I also added a DHT22 sensor for temperature and humidity sensing inside the box.

Schematic of the voltage dividers used for the power monitoring circuits

The ESPHome configuration for these follows. I also added a binary status sensor and a WiFi signal sensor to allow me to monitor the system remotely.

binary_sensor: - platform: status name: "Shed Lights Status" sensor: - platform: wifi_signal name: "Shed WiFi Signal" update_interval: 180s - platform: dht pin: GPIO15 model: AM2302 temperature: name: "Shed Battery Box Temperature" humidity: name: "Shed Battery Box Humidity" update_interval: 180s - platform: adc pin: GPIO39 name: "Shed Battery Voltage" icon: "mdi:car-battery" attenuation: "11db" filters: - multiply: 4.24 - sliding_window_moving_average: window_size: 12 send_every: 12 update_interval: 15s - platform: adc pin: GPIO36 name: "Shed Solar Panel Voltage" icon: "mdi:solar-panel" attenuation: "11db" filters: - multiply: 5.73 - filter_out: 0.00 - sliding_window_moving_average: window_size: 12 send_every: 12 update_interval: 15s

The voltage readings I am getting from the two voltage sensors are a little weird. The battery voltage is higher than I would expect and the solar panel voltage is lower. I double checked the multiplication factors against the raw ADC readings and the resistors used and the readings make sense. Initially I thought this could be due to the temperature inside the box (~50°C when it’s in full sun!), but now I’m not so sure since this is also the case at lower temperatures. It could be the behaviour of the charge controller. I’ll continue to monitor it over different charge states.

The card in Home Assistant showing the system status and lighting controls

The Finished Product

Now the moment you’ve all been waiting for – gratuitous photos of the LEDs in fancy colours!

In white, the intended operation mode

Red is insanely bright!

Green

Blue

Purple/pink, the favourite of some people in the household

Finally the rainbow effect, the other effects don’t come out so well in a still photo

Conclusion

This is actually my first time using the WS2812B LED strip and I have so say I’m really impressed. You can be sure there will be other LED lighting projects coming in future now that I’ve dipped my toes in!

I’m really pleased with the final product. The LEDs look awesome and provide ample light for their task. The ESPHome base has so far been rock solid in terms of stability, which is what I’ve come to expect from using it in other projects.

The initial intention was to make these lights motion activated. However, I couldn’t find a motion sensor which was suitable for outdoor use. I’d also have to locate the sensor at the other end of the sheds from the battery box which would mean a whole load of wiring. As such I’ve decided to build by own wireless outdoor motion sensor and connect it to my MySensors network. I’ll then trigger the LEDs via an automation in Home Assistant. I’ll post an update on this when I have it running.

This has been a really fun and interesting project. As always, please let me know what you think in the feedback channels and feel free to share your own LED lighting projects.

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