I have a HomeWizzard energy meter connected my pv fox invertor. This meter is readable by API. I like to add this meter to cerbo as “pv invertor” by using node red. I have some programming experience in c++. But node red is completely new for me. My system is a production system and should not be taken down on a whim. I know I should update cerbo to the large image and believe this should not interrupt the multiplus. Can anyone point me to an absolute beginners tutorial node red on cerbo? I have surched on Google and found a lot, but they are all going to fast for me or assume some node red knowledge. Is there a way to install the cerbo software in a vm machine and test my “skills” there so i don’t break the running system?
Thanks in advance for maybe some helpfull links and info.
No need for a VM, just update to large image. The MP will continue to run, but anything that is controlled by the Cerbo itself will stop for a moment, meaning ESS for example. Same as when any other VenusOS update is installed.
Each flow can be enabled/disabled on its own. So if you think your flow breaks something, just disable it.
If you really want to run a seperate nodered instance, then you very likely have to choose a seperate host to run it on. It can run on windows, but its installation process is a bit complicated
So you say that changing to big image should not break anything? And as long as i only read stuff and nog try to push all kinds of bs into the system it should be OK?
I have two goals at te moment: create a “software pv invertor” so my pv invertor data becomes visible in the cerbo grafic screen, and maybe add my p1 meter to cerbo as a grid meter.
I have tested it. I can query it 10 times a second, easily and doesn’t skip a beat.
But why would 1 times a aecond for example be to slow? I don’t criticize your opinion, I just don’t understand why that would be to slow? I’m trying to learn.
It also depends on your general system, how the load behaves, if theres an AC coupled PV, so on. It might work fine or it might not.
If it doesnt then it will show itself as the grid import/export fluctuating around the setpoint. In mild cases a few tens of watts, in worse cases a few hundred watts.
Im using a Shelly 3EM which is also not officially supported as a grid meter, and it works fine most of the time. I can see power fluctuations from the MP whenever the small air compressor in the shop kicks in. Its power spike is registered by the system, the MP reacts to that, a second later the next measurement comes in, which again shows lower load since the compressor is now running, then the MP corrects down again. It all takes a few seconds to regulate to the gridsetpoint again. Everything else, which does not have an inrush current, is regulated out smoothly.
Even if it doesnt work, you seem to be able to increase the poll rate, so you could make it faster. Or change to another meter down the line.
Who cares? There are rules for the German grid that the inverter is not allowed to adjust it’s power faster than with 400 W/s.
I use the Shelly 3EM as a grid meter, and I have no more than 1 to 2 kWh of unwanted grid import or export per month! Per month! It is not worth the time to discuss such trivialities.