Hi All - my first venture into Node-RED, and I’d appreciate your advice. First I’d like to determine the hardware needed - later I’ll figure out the programming logic.
Goal: minimise grid consumption: I would like to add intelligent automation of when a 4kW geyser, 2kW geyser and a 0.75kW pool pump turn on and off, depending on the amount of solar (max 5kW output) and charge level of a 9.6kWh battery connected to an EasySolar-II 48/5000/70-50 MPPT 250/100 GX (all-in-one with integrated GX).
The max continuous output of the EasySolar is 4kW, so the geysers should not turn on together to avoid drawing any more from the grid than is the minimum possible. Similarly with when the pool pump runs. The house background power consumption is 600W. When large appliances run the geysers may have to be turned off temporarily to minimise total consumption (above 4kW) and power supplemented from the grid. When there is spare solar, and the battery is full enough, and the consumption by other devices is at suitable (low) levels then the geysers must be turned on alternately, and lastly the pool pump run for as long as there is excess free power.
It’s a single phase grid feed and a Carlo Gavazzi ET112 energy meter is connected to the EasySolar.
All plugs and lights are fed from the EasySolar AC-out. The two geysers, pool pump, stove and two air conditioners are connected on the grid side of the EasySolar, so they lose power entirely during a grid outage and the automation understandably won’t run during outages.
I believe the GX only has one relay output, so this would best be done with one Shelly Pro 4PM switch (leaving one free channel) and one relay for the 4kW geyser in the distribution board.
A flaw in the design above is that a 4kW geyser is above the current rating of a Shelly Pro 4PM, especially with long-term switching, so an external contactor would be needed, in which case the Shelly Pro 4PM would not measure the current to the geyser.
The Shelly Pro 4PM cannot accept a signal from an external current transformer clamp, so a different solution is needed. I want to be able to turn a circuit on/off from the distribution board, without needing an app or web connection.
Yes, the energy meters in the “integrated” Shelly units appear to be limited to the rating of their switching relays (which makes perfect sense)… they do make standalone energy meters (and you have several choices supported by Victron. Perhaps use relays from a Shelly or GX IO-Extender to drive a contactor for the bigger load?
Thanks for reading my post and giving some ideas Dean.
I was not aware of the GX IO-Extender, but if only Victron had made it with four relays rated at a minimum of 25A!
I was hoping for a solution with one integrated energy meter + relay(s) unit with at least three channels - basically a Shelly Pro 4PM rated at 25A per relay. I’m trying to avoid a fragmented solution, but the most cost effective I’ve come up with yet is to use 2 channels from a Shelly Pro 4PM plus a Shelly Pro EM-50 + external contactor for the 4kW geyser switching. Three components where I wanted one.
Do you think the the GX IO-Extender would be a better solution, or offer more options going forwards? I’m not sure what else I could do with it - yet…
Thanks
In general, I like the GX IO-Extender as a product, I hear you on the relays. Also, the drive current for the digital outputs could have been a bit higher - 4 mA won’t even drive an LED, let alone a relay coil
I have also used Shelly devices in several projects.
The Node-RED integration is great with both solutions.
The Shelly devices win when you want the switching to happen at some distance from where the Victron gear is located… You only need AC and connectivity to the same network as the GX device (Ethernet or WiFi).
If your Victron gear is right next to the switchboards with your gadgets, either solution is good.
Interesting Alex. Claude dug out that it is manufactured by a company in Shenzen and contains a Shelly chip and can be controlled by Node-RED. Shelly maintains the firmware but other support queries must continue manufacturer.
It is extremely well priced and would almost halve the cost of the energy meters and relays compared with the Shelly products discussed above. Apparently there are DIN rail brackets available.
These have no switch to toggle a geyser or pool pump one/off, but do have connections for an external switch, but these must not contain an LED as the small bleed current can apparently confuse controllers. I didn’t see if there was any status light or a way to wire one up.
Unfortunately, I don’t have this relay, so I can’t speak from experience regarding the LED. But the us.shelly.com website expressly states in the description that it has an LED indicator, whereas the main shelly.com site doesn’t mention it at all.
