DC meter for PV ouput measuring and data logging

  • 0_1494333610637_PV.png

    Hi all,

    I want to install a dc meter between my solar panel and battery for recording (logging) PV generated output from Solar panel. Also i am thinking to connect another meter after the battery to see outgoing power after the battery. My questions are:

    1. Are there any feasible and cheap solutions to make certain circuit based on Voltage current hall sensors with MCU's to record PV generated data ? what could be the method to store analog data coming from sensors to store in some memory.

    2. Any cheap product in the market for dc parameter measuring and data logging. (at least for 2 months).

    Thank you. this is my first post here i will look forward for responses from you guys.


  • Mod

    Where do you want to store your data? Because there are plenty of tutorials on how to log data, there are also online services that help you log data (like thingspeak), but if you want there are also some home automation controllers that you can run on a raspberry pi (or whatever other hw you like/have) and use mysensors for communication between sensor node and your controller. There are also more advanced solution that you can use, it depends on the level of detail you need and how much you are into tech 🙂

  • Hero Member

    @tailchopper It would depend on the output voltage & current of your PV panel. Up to 26V 3.2A the ina219 is a very convenient all-in-one sensor with I2C interface.

  • Thanks gohan.

    I want to store data in any kind of memory linked to my PC and later i could use it for calculation and my record purpose. Currently I dont want to use website or online portal for communication. I am kind of novice but have some knowledge in electronics field. System contains 8kWh battery. For test purpose i want to monitor and save the data.

  • Mod

    My ideas:
    Easy way: one esp8266 with current sensor (as stated above) and something else to read voltage (either an analog pin with voltage divider or any other ADC converters ); load esp8266 ethernet gateway sketch on the module and start adding the code to read and send data to the controller; install a controller (Domoticz or other you like more) somewhere and att the gateway to the hardware list and start receiving your data and you also have graphs. More advanced data logging could be done using Grafana or you could use node-red to save data to whatever DB it is supported (there are plenty of tutorials around). It is up to you how deeply you want to go 🙂
    Data logging can also be done to a microsd card if you really want to keep things to a minimum 😄

  • Contest Winner

    @tailchopper does your power inverter not have any data interface to read out the measurements?
    Most common inteverters do have such interfaces, mine has a RS485 interface for which i made some tools to collect and store the measurements.

    Using such an interface is most often more reliable

  • @BartE I want to measure the PV module output which is going into the battery.. and output from battery to inverter.. There is only a meter connected at the load side after the inverter (AC) which gives load consumption data however i am blind at the input side (PV). By getting the data i would know many things happening at the input side (losses,efficiency,PV generation etc) currently there is nothing to communicate with PV and batteries.

  • @gohan thanks..But please go a little slower (I know you are a pro but i am just thinking how this connection will work) You mean i could use ESP8266 with any controller (controller will read the data from sensors) and then controller will connect to ESP8266 for sending data over the internet. But for now i just want to measure the data and store it somewhere in any memory. Wifi and other stuff comes next i guess. Can you please draw me a rough diagram for explaining this connection?

  • Mod

    No, you connect your sensors to the esp8266 and then the controller will read data from it and store it, the alternative is to send data directly from esp8266 to a cloud service (they have their own libraries for that and examples) but usually the free services don't hold data for very long time, but to make a proof of concept it could be fine.

  • Thanks for clarifying. System would generate approx 600 Volts and 8 Amps from PV. Hardly there would not be more than 15 I/O's . Which would be cheaper and reliable option for controller to use with esp8266 ? Are there any controllers specifically for data monitoring? lets say if i connect voltage and current sensors directly to that controller ? I know there are some DSP's in the market but they are too expensive. I have seen LV-25P and LA-P sensors for voltage and current sensing in another circuit however never interfaced by myself.

  • Hero Member

    @tailchopper I wonder if you wouldn't be better of on another forum. MySensors provides an infrastructure for home-automation and IoT. If you are not into connecting it to a MySensors ecosystem there are some dedicated PV (power monitoring) forums which probably give you more focussed / better answers. Like Openenergymonitor

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