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rotortalk avatar image
rotortalk asked

Can I control the AC-Input relay via an aux input?

I have been looking at all the assistants and the Virtual switch but I cannot find what I am looking for.

Is it possible to switch the AC-Input ON and OFF by using the Aux Input? I'm in the UK and only want to take grid power when it is cheap or I need it. The cheap (Octopus Agile) tariff is not a fixed time, so I want to be the one (well, a Pi at least) to control when I can take energy from the grid.

I was planning to use an external contactor to shut down the grid connection, but since there is one in the Quattro it would be nice to use that.

I think I could achieve a similar thing by using ESS and forcing the charge rate to 0 on a signal on the aux input, but it doesn't feel quite the same...

MultiPlus Quattro Inverter ChargerESS
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shaneyake answered ·
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wkirby answered ·

The backfeed relay is a safety component, it cannot be externally controlled at all.

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rotortalk avatar image
rotortalk answered ·

I have to disagree, because it can be controlled by the Virtual Switch and conditions such as Load or Battery Status which are not safely conditions. i.e. Ignore AC input until the load is more than x. This is perfect, I just want to add a condition, "Ignore AC input unless Aux 1 > 2v"

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wkirby avatar image wkirby ♦♦ commented ·

Those VS conditions are internal conditions.
What I meant before was that there isn't an option for direct external control of the backfeed relay.

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rotortalk avatar image
rotortalk answered ·

@shaneyake - that is perfect. Thank you! My searching skills weren't good enough.

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wkirby avatar image wkirby ♦♦ commented ·

To be fair to yourself, Mark only posted his solution a few hours ago.

I did not think about doing it that way. I have tested it on my test setup and it works!
So, my apologies but at least I have learned something new today :)

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rotortalk avatar image rotortalk wkirby ♦♦ commented ·

Yes, I saw that. It seems we both had the same question at the same time! I'm super happy it works. One less piece of hardware

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wkirby avatar image wkirby ♦♦ rotortalk commented ·

I'm curious on how or what you are querying to know when the lowest Octopus rate is active?

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rotortalk avatar image rotortalk wkirby ♦♦ commented ·

I don't know where you are based so I hope I'm not teaching you to suck eggs, but Octopus Energy in the UK has a tariff that is based on the wholesale price of electricity which is a first for us (I only learned this week, after reading horror stories of huge bills in Texas following the storm it seems common in the US)

So Octopus publishes the next 24 hours pricing at roughly 4pm each day and it is available via an API on their website, so it is a trivial call (in my case using a Raspberry Pi) to their server to get the prices, broken down into 30 minute intervals for the next 24hrs. Then, combine this information with the state of charge of ones batteries, the weather forecast, also broken down into 1/2 hr intervals to predict the solar output and you can optimise what little you take from the grid at the appropriate time. If solar isn't going to cover you for the next day, load up at night!

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