Hello everyone,
I’m living in spain and i’m going to install solar panels in my house and disconnect it to the general electricity. ( in spain there are many tax if you stay connected), so no choice.
I found this project because i wanted to check if it was possible to monitor the energy produced by the panels and used by my house with arduino and/or raspberry and i found this… Amazing project.
Can you confirm that buying the emonPI and the emonT v3 is enough to monitor it?
Thank you
Yes. And welcome.
But two points:
- Will your inverter tell you how much power is being generated?
- I think you have 3-phase electricity in Spain, therefore you will need to buy a programmer so that you can install the correct sketch to measure 3-phase power accurately. And the 3-phase sketch needs to have a voltage and 3 current transformers, so you need those, as well as anything the emonPi needs (5 V d.c USB, plus voltage and 2 current transformers if you need them.)
And I think you will also have a battery that will provide power during darkness?
If you want to measure the power at more than one place, then it is possible that you will need more than one emonTx. But I cannot be certain without knowing more details about your plans.
Hello robert and thank you for the answer.
Yes indeed, you’ll need more details.
So, there are 2 inverters in parallels and 24 2v batteries (48v battery)
Yes during the night the batteries will do the job.
The inverter will tell me from where he is picking the power:
From the panels or the batteries or the power generator (in extreme cases)
This is one phase only, at least i think, there is only a +, a - and the ground.
The inverter will tell me how much power is generated.
I thought that with the emonPI solar bundle it will be enough because at the end everything can be measured at the inverter right?
You must find out what your electricity supply is. A clear photograph of the inside of the panel where your main switch and circuit breakers are might tell me enough. Without that, I cannot say what will be suitable for you. If it is single phase, and you can get data from your inverters, then the emonPi Solar Bundle (and no emonTx) should be suitable.
If you want emonCMS to record the inverter data, then either you must make sure the inverter can send the information in a form that emonCMS can expect, or you need software in the emonPi to get the data from the inverter. I am not an expert in that area, so I cannot help you there.
Ok, i’ve called my inverter supplier and i can’t read the data from it except from the screen of the inverter.
Electricity supply is 1 phase. With 2 CT sensors from the emonPI it’s possible to get those input power and output power data no?
Thank you again for your help
Am I right that your inverter will work from either the solar panels or the battery, and when it is generating from the solar panels, it will also be charging the battery?
You can have your emonPi to measure the power that your house consumes, but because your inverter cannot tell the emonPi what it is doing, and the emonPi cannot measure direct current flowing either from your solar panels or in or out of your battery, I cannot see how you can have the emonPi record how much power is being generated, so that by subtracting the power that your house is using, you can calculate the third power…
If you can build electronic circuits around an Arduino, then you can measure the current in the battery, and then you would be able to deduce what the solar panels were generating.
Good day, robert and again, thank you very much for your help.
Yes, you are totally right!
I get it now, the most important is to know how many power the house consumes for me and i can get it with the emonPI in real time so that’s fine.
I do have an arduino uno that can do the job, i was using it to control my lights but now i’m using a raspberry and an app.
It will be fun! if i managed to do it and if you are interested in it i can post it.
Thank you again robert.
If you buy the RFM69Pi radio module for your RPi, or use a serial connection, you can use your Arduino with the emonTx Shield instead of the emonPi. There’s enough power in the RPi to do emonCMS and still control your lights.
ok, thank you, i’ll check it.
I’m sorry if i come back to it, but i don’t understand.
You have an emonPI bundle solar pv bundle which come with 2 CT sensors to get the solar PV and the power used in the house.
On the schema on this page Solar PV - Guide | OpenEnergyMonitor there is not data sent by the inverter to the emonPI, so why can’t i do it too?
You can do it, but if your battery is connected to the same inverter as the solar panels, and you have no grid connection, then the power out of the inverter is the same as the power in to your house. The two must be the same - there is nowhere else for the power to go.
Ok i get it.
So, if i only buy the emonTX, with my raspberry i can use emoncms and get the consumption data?
I don’t need anything else right?
Thank you Robert for your patience
Let me outline what each of the emon range of items is:
An emonTx measures 4 currents, 1 voltage and has a Atmel 328P processor and a RFM69CW radio module to send the data. It also has a serial data connection if you do not wish to use the radio.
An emonTx Shield is the same but it has no processor, and it sits on top of an Arduino board that provides the processor and the serial connection.
An emonPi is a 2 currents, 1 voltage emonTx and a Raspberry Pi all in one box. It can receive data from one or several emonTx’s. The emon part and the RPi communicate serially.
Therefore, you could
- Use your Arduino plus emonTx Shield connected serially to your RPi, or
- Use your Arduino plus emonTx Shield and add a RFM69Pi module to your RPi and connect the two by radio, or
- Buy an emonTx and do Nos. 1 or 2 using that instead of your Arduino + emonTx Shield, or
- Buy the parts for an emonPi without the RPi and use your RPi.
And I am sure there will be a few more possible ways to do it.