I would like to automatically limit the production of my AC-coupled SolarEdge PV inverter when the grid price becomes (too) negative. So when the battery is not yet full, I want to charge it from the grid instead of from PV. That makes sense financially and helps the grid. Until Venus OS v3.70~23 I would do that by writing a percentage to the Fall-back Active Power Limit Modbus register (0xf312) of my SolarEdge using node-red. I have to use a Modbus proxy because the SolarEdge doesn’t support multiple simultaneous client connections.
After the upgrade to Venus OS v3.70~27 that no longer works because it writes 100% to the Dynamic Active Power Limit Modbus register (0xf322) every 5 seconds, so it never enters fall-back mode. I tried writing the Power Limit (W) property of the PV Inverter Control node. That value is sent to the SolarEdge once, but it does’t change the active value that Venus OS is writing every 5 seconds.
So what are my options? Perhaps I can disable the Dynamic power limiting setting while my own limiting is active, but I haven’t yet found a way to do that from node-red. It would be more convenient if Venus OS would either stop writing the Modbus register when the power limiter is at 100%, as it was before, or when there would be a way to influence/overrule the power limit that it is using internally.
My conclusion is that the Dynamic power limiting of Venus OS is not usable for me and I disabled it. I have a node-red flow that calculates the desired power limit and writes it to both the Fall-back Active Power Limit and the Dynamic Active Power Limit registers when the limit changes. It is a bit cumbersome and it requires the use of a Modbus proxy to avoid conflicts between Venus OS and node-red.
Could you elaborate on how you control dynamic power limiting? I have an issue with the out-of-the-box implementation of it with my SolarEdge inverter. It is not clear why, but even if the dynamic power limiting settings are disabled, VRM/Cerbo (unclear what is controlling this feature) decides to switch off the inverter between 10 and 11am. Extreamly annoying that exactly when the PV yield is the highest something just switches the inverter off
When the dynamic power limiting is switched off in the Cerbo, it shouldn’t throttle or switch of the inverter. To me this sounds like the inverter is switching off because the AC voltage is to high. Did you check that? You should measure the AC voltage close to the PV inverter as the cabling could introduce some voltage drop, or look on the display if your inverter has one. Unfortunately, the AC voltage of my SolarEdge inverter is not reported to the Cerbo as it uses a non-standard Modbus register for it ( fix missing AC/L1/Voltage voltage for 1-phase SolarEdge inverters by streef · Pull Request #13 · victronenergy/dbus-fronius · GitHub ). With my grid code, the PV inverter switches off at 253V.
My installation is relatively new, this is the 1st summer since I have completed it. So my experience is quite limited, which is why I haven’t haven’t encountered this before. Makes total sense, though… The PV inverter switches off shortly before noon and only on the sunny days. Probably when the grid voltage is getting higher due to the abundance of available power. More supporting evidence is that I’ve just deleted the Sunspec connection between the Cerbo and the SolarEdge and restarted the Cerbo. Still, the PV inverter shuts down.
So I’m heading upstairs to measure the voltage at the SolarEdge, before I’ll just probably switch off the mains so the PV can charge my batteries. Thanks a lot
Dick, there is imo a way to achieve turning off your solaredge inverter at a certain monetary point, say -12 cent per kWh.
Configure the NRO inside your solar app to be symmetric for export and import rate and to be both active at -12 cent per kWh or less ( or any other number). The solaredge inverter will stop production, exactly what you want, you can then import electricity from the grid …
For the normal negative pricing, between -0 and -12 you can use the dynamic power control, you can switch that on and off using /settings/fronius/inverters/“your solaredge sunspec inverterid”/EnableLimiter (1 = enabled, 0 = disabled).
The NRO is even better if you have a solaredge grid meter installed, then it reduces the production to the amount needed in the house ( with or without batteries) but with Victron’s control of solaredge that is tricky …
