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SmartSolar and BMV-712 - Switch loads depending on actual solar power (virtual load output)

Hello!

At the moment I am planning a small setup with the following components:

- SmartSolar 100/50 with one or two solar panels (approx. 500W).
- MultiPlus 12/500/20 or 12/800/35 for AC and to support charging from grid.
- 12V LiFePO4-Battery with a BMV-712 Smart attached.

It should roughly look like this:

victron-skizze-smartsolar-bmv-712-multiplus-vesmar.pngThe setup should stay as slim as possible, to save cost an overall installation space.For the controls I also don’t want to get too fancy. The only needs are a Switch (to turn AC on/off) and a Display for SOC (BMV-712).Settings should be done via Victron Control app.

In order to save energy and prevent the battery from running out too soon i need to switch Loads on/off under certain conditions:

- The BMV-712 can switch off / or set an alarm when SOC drops below desired value. This is very useful for some cases and should be used. But it cannot cover all needs.

- The SmartSolar can switch loads with its virtual load output (when adding a VE.Direct TX digital output cable). I have found Load output settings depending on Vbatt and the streetlight settings. Both are nice but don’t seem to do what I am looking for…
Desired function:
The fridge should only run (on 12V) when enough solar power surplus is available because it should not unnecessarily drain the battery, especially after dark.

Q1: Is there a possibility to switch consumers depending on the solar power currently available?
For instance: Turn on load switch if P(solar)> 100W
I know this kind of feature from residential PV-installations where it works like a charm.
Have i missed a setting or would this be a #feature-request?

Q2: I have read somewhere that this virtual output delivers only 5V and very little power.
Which relay (specs) could I need to use for switching my 12V components?

Help and hints appreciated!
Thank you.



MPPT SmartSolarBMV Battery Monitor
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snoopv avatar image snoopv commented ·

Found the answer to my Q2

here: 5.2.5. TX port settings

**) The TX port is a logic 5V signal. It can drive a maximum of a 22kOhm impedance load, where the output voltage is dropped to 3.3V. Make sure that the connected load is within this specification.

In other words: To be safe you would need a SSR Relay (with min. coil voltage of 3V and less).
And maybe even some standard 6V-Relais could work, depending on how much load the TX port can power.



… only Q1 left: How to switch loads depending on the solar power?

Any ideas??


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