question

dandenson avatar image
dandenson asked

relay 'macro' in VRM?

I would like the ability to put a script/macro in for relay control that is triggered from VRM.

Here's the use case, might make it more clear.

I have an off-grid site up in the frozen north that is built to handle the temps, has 4 days of battery and 600W of power. The only problem is that the solar panels ice or get sticky snow on them which takes my normal overcast skies output from 100W down to 10W and that's not enough to charge batteries and run things.

I have added resistive heat strips taped on the back of the panels and triggered via relay. This works great, pulling power directly off the panels (via Y on the cables) and just a little heat is enough to get the snow and ice to slide off the panels.

I'm having to use a separate controller to handle this, which is of course using up a bit more power but also adds a layer of complication to the system.

I would much rather have a 'run for 10 minutes' button on the VRM dashboard for the site that would close the relay for 10 minutes and then open it back up. Simple as that.


Thanks.

VRM
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2 Answers
Trevor Bird avatar image
Trevor Bird answered ·

Hello @dandenson ….. I think you could use the generator start function of the CerboGX for that use. Simply wire the relay output of the CerboGX to power the heating strips. Go to the remote console of the CerboGX within VRM and manually start the “generator” after having set a run time of 10 minutes.

You may be able to use another relay as well but this is a definite solution without having to investigate other options.

2 comments
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kevgermany avatar image kevgermany ♦♦ commented ·
Will the Cerbo relay handle the current? I think it would be prudent to use the Cerbo to switch a relay that is more suited to the task.
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Trevor Bird avatar image Trevor Bird kevgermany ♦♦ commented ·
Oh yes I agree….. the current through the Cerbo relay should be designed to be fleapower.
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dandenson avatar image
dandenson answered ·

yeah, just after I posted this I noticed 2.90's changelog added the generator start option. Be nice to rename it but I guess I'll take what I can get!

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