Solar panels are popular because they are able to give us energy from light. When the light hits the panel solar conductor, the energy is translated into moving and electrons, creating current. In this newsletter we´ll make a simple monitoring system that you can develop for your home with Open Source Hardware.
Hardware selection depend a lot of your solar panel and its specs (output voltage, power). For this project, we will consider that we have a 5.2 kW solar panel which provides between 0-10V. The required hardware for the project is:
- Ardbox PLC.
- A Panel PC.
- Allegro ACS712: ACS712 chip allows DC and AC current measurement. The value read from the sensor is proportional to current measured on the sensing terminals. Datasheet can be downloaded here.
- A Solar panel! We will use this one from Sparkfun.
- A Solar Inverter, which converts the variable direct current (DC) output of a photovoltaic (PV) solar panel into a utility frequency alternating current (AC).
- Wires and resistors (for the voltage divider).
On the other hand, to measure Voltage we will use a voltage divider circuit. As the ARDUINO analog pin input voltage is restricted to 5, the output voltage must be less than 5V. See the schematic: Software and code
Basically, the code measures each 5 seconds current and voltage, and, with these values, calculates the power. Later, sends these three values to the Panel PC.Regarding the voltage measure, Arduino ADC converts Analog signal to corresponding digital approximation.Regarding the current measure, we consider the following points to take into account:
- Analog read produces a value of 0-1023, equating to 0v to 5
- In our case, Analog read 1 = (5/1024) V =4.89mv, Value = (4.89*Analog Read value)/1000
- But as per data sheets offset is 2.5V (When current zero you will get 2.5V from the sensor’s output).
You can download the code in the following link: Going Further and key benefits Solar panels come in many varieties. When shopping a solar panel for your system, there are a few specifications you need to follow. Contact us! Do you have a process to be automated? Contact Industrialshields to buy the proper hardware and Opiron to implement the entire solution.