This is an exciting site with a lot of interesting projects.
I have just had my solarpanels and a ventilationssystem with passive heat recovery (Nilan Comfort 300) installed in my house. Now its time to monitor....
The basics is that i have 3 phase supply from the grid and 1 phase inverter from the PV setup.The inverter is a Solutronics SP35 which can supply production data through RS232 or RS485. There is also the possibility to fetch data through an ethernet port but this is a binary protocol that I don't think my programming skills are good enough to utilize.
My present electricity meter is a dial type but soon the electricity company will exchange that for a electronic type with a IR blinking 400 times for every Kwh being used
I was planning on using my newly bought RaspberryPi to get data from the inverter through a RS485 cable. At the same time build and install the PV and home monitoring system. I have some questions though.
Base station and CMS should be on the RaspberryPi with a RFM12PI supplied by a emonTx with 1 CT and a AC-AC adapter (later a IR detector) temperature sensors etc.
- For my setup 3 phase in and 1 phase inverter i need 4 CT's Do I need need 2 pcs of emonTX for this?
- Could the EmonTx shield be used in stead of 2 emonTx'es to monitor 3 grid phases and one inverter phase?
- Could I rely on the blinking Ir led on the new meter in stead of the CT's?
- Alse if I use CT's, do i need 4 AC-AC transformers or could i do with just 1?
- If I succeed in getting the inverter data out through the RS486 interface, will it be possible to display these data alongside the Emon data in the emoncms?
- Which frequence should I choose 433MHz or 868MHz? I guess there will be fever systems on 868MHz so there i should expect less interference using this frequency – but then shorter range.
I am fortunate to have a contract with the electricity company that lets me get my surplus production of electricity in the summer back at no charge (no tax, no vat etc.) within a year.
I have soldering skills but my programming skills are very old and rusty – aka haven't been used since 1975.
Sorry for my many questions. They reflect my lack of knowledge in this area.
Re: What shall I choose?
Just dealing with the power side (I'll leave the CMS & RaspberryPi to others more knowledgeable in those areas).
If you want to measure the true power across 3 phases, then you need a voltage monitor on each phase. It's possible to use just one, but then you have to assume the phases are perfectly balanced voltage-wise. That could lead to errors.
Have a read of this thread to see how 3 emonTx's can be stacked to read 3 phases.
Have a read of this one where you should find details about reading the LED on your meter (and what it means!).