Monitoring my solar panel power production

I have recently acquired two solar panels from Sunology advertising a cumulated instantaneous production of up to 810W. The panels come with a smart plug emitting the data to Tuya, in order to retain and graph historical data. However, the only available granuarity for that data is daily kWh production. In order to optimize the orientation and placement of the panels, as well as measure the production efficiency (power produced / 810 * 100), I needed a much finer granularity than that. I decided to query the data myself and send it to Datadog.

information flow from plug to Datadog

The first thing I needed to do was to find a working client that would be able to talk to the plug. It seems that tinytuya would do the job. However, it didn't seem like I could simply fetch the data from the plug locally. Instead, I first needed to create a Tuya account, a cloud project, and add the plug to the project devices to get both an API key as well as a key for the plug. That proved out to be quite tedious, as the Tuya IoT interface is very confusing and slow, but I managed thanks to these Home-Assistant instructions.

With that data now available, I was then able to setup the tinytuya client on a Raspberry Pi with network access to the plug IP.

$ python -m tinytuya wizard
TinyTuya Setup Wizard [1.12.4]

    Enter API Key from [REDACTED]
    Enter API Secret from [REDACTED]
    Enter any Device ID currently registered in Tuya App (used to pull full list) or 'scan' to scan for one: [REDACTED]
    Enter Your Region (Options: cn, us, us-e, eu, eu-w, or in): eu

>> Configuration Data Saved to tinytuya.json
>> Device Listing
>> Saving list to devices.json
    1 registered devices saved

>> Saving raw TuyaPlatform response to tuya-raw.json

Poll local devices? (Y/n): y

Scanning local network for Tuya devices...
    1 local devices discovered

Polling local devices...
    [Sunology                 ]      - [On]  - DPS: {'1': True, '9': 0, '17': 109, '18': 2704, '19': 6491, '20': 2379, '21': 1, '22': 529, '23': 26153, '24': 13705, '25': 3040, '26': 0}

>> Saving device snapshot data to snapshot.json

>> Saving IP addresses to devices.json
    1 device IP addresses found


At that point, the tinytuya wizard script had scanned the networks the Pi was connected to, found the plug, and was able to connect to it via the provided device key.

I then created a dedicated APP/API keypair on Datadog, and scheduled this python script to run every minute via cron.

# Run every minute via this crontab
# * * * * * cd /home/br/tuya && /home/br/tuya/.env/bin/python

import json
import time

import datadog
import tinytuya


with open("devices.json") as device_file:
    device_data = json.load(device_file)

plug = tinytuya.OutletDevice(

plug_status = plug.updatedps()
data = plug_status["dps"]

now = time.time()
metrics = []
if "18" in data:
    current = data["18"]  # mA
            "metric": "solarpanel.current",
            "type": "gauge",
            "points": [(now, current)],
            "tags": ["location:terrasse_1"],

if "19" in data:
    power = data["19"] / 10.0  # W
            "metric": "solarpanel.power",
            "type": "gauge",
            "points": [(now, power)],
            "tags": ["location:terrasse_1"],

if "20" in data:
    voltage = data["20"] / 10.0  # V
            "metric": "solarpanel.voltage",
            "type": "gauge",
            "points": [(now, voltage)],
            "tags": ["location:terrasse_1"],


At that point, the measured current, voltage and power was sent out to Datadog every minute, and I was then able to create the following dashboard:

Dashboard detailing electricity production over time

This dashboard makes it seem like the panel can only hit 75% efficiency, when I have seen them hit 95-99%. This is due to the Datadog point interpolation happening on large time windows. When we focus on a smaller window, we can see these high (albeit brief) peaks.

With that granularity, I realized that the panels only started to really kick in after midday, and that I should probably move them to a spot with more exposure if I wanted to produce more than 4kWh a day (measured on a hot and sunny day without any clouds). That day, I only hit 85% efficiency though, even though I had hit 99% at some point during the previous weeks. That makes me wonder if I need to wash the panel.

Edit: it rained that very night and I did hit 95% efficiency the next day.