Mycroft Community Forum

Off-grid DC system use

Has anyone ever set up Mycroft on an off-grid DC system ?
What I’m thinking off specifically is using a smart plug to allow recharging a DC battery on which the entire house electricity system runs. This way, it can allow for recharging of the DC battery during off-peak hours (which is cheaper). The AC devices (because most domestic household items can only be bought in AC-version) are powered from the DC battery through an inverter. Additional smart plugs can be placed in power sockets in which certain AC appliances sit (washing machine, dryer, dishwasher, …) thus allowing to run only if enough power is left in the battery (because you don’t want the battery to get too low either as it’s bad for the battery itself and you may want to reserve some extra power for other devices (lights, TV, refrigerator).

What’s tricky here is that many power companies no longer set specific times for off-peak and peak hours but rather use a digital meter in which any time during the day can be peak or off-peak, depending on the exact time and energy demand/supply ratio on the grid.

I might have not been entirely clear here: I mentioned it is a “offgrid” system but really it 's a sort of hybrid system as it is grid-connected but not directly (only the battery connects to the grid and the system can and would be detached whenever no recharge of the battery is needed). This is useful for economic and ecological reasons (it requires the use to be more energy conservative and obviously, energy costs are lower if only drawing power at off-peak hours)

I still fail to see how this is related to mycroft.

There may be a related question hidden in his posts (running mycroft offline) but it’s overshadowed by the extraneous bits.

Well, its pretty obvious how it is related to mycroft: mycroft would handle the automation of the system. For instance, it would decide when to deactivate any of the smart plugs when it detects the battery capacity gets too low. Also, it would start the recharge of the battery when battery is low and off-peak hours get into effect (after a certain hour and untill a certain hour of the day), or if the power company tariffs change depending on current power draw/network stress, then it needs someway to know it’s currently off-peak or peak hour (this is often done by power companies through a smart meter system, so needs to be able to connect to this somehow).

Lastly, manual activation (speech) should also allow the user to recharge the battery manually, show present current power capacity of the battery, show power draw of each smart plug or activate/deactivate particular smart plugs.

Mycroft could also automatically disconnect the battery with an additional switch for safety (in case a solar storm puts excess power on the grid, possibly also damaging appliances in connected homes). This is quite exceptional to occur, but it would give extra ease of mind to owners of the system, and an extra reason on why to install such a system.

Another thing I think of is that, when connected to a smart meter, and if the owner has photovoltaic panels and has a net metering agreement with the power company, it could allow giving current power transmission (kwh) data to the user (but that’s perhaps more of a gimmick). More interesting is allowing Mycoft of showing monthly or weekly energy production data and the possible energy production (available watts/m2 for that location x 24 hours x one week or month). The idea here is to give the user information on how he best sets the panel tilt for that month or 4 months or orientation for optimal energy production, hereby increasing revenue for the user.

With the right skill programming mycroft “could” do this but “should” mycroft do this? mycroft is really developed as a smart speaker interface and already has skills to interface with openHAB and Home Assistant which are better equipped to handle the automation side of things (IMHO). With that said mycroft works great to trigger said automations as well as an automation event notification client.

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OpenHAB has a SmartMeter Binding which “reads SML messages (PUSH) and supports IEC 62056-21 modes A,B,C (PULL) and D (PUSH).

If such device is present OpenHAB will most likely be able to interface it. And in this case the existing skill could be expanded to cover this function.

And if you are capeable of monitoring (or interact with) this device, Node Red (skill) is also a possibility to “do something with this data feed”.
Have a dumbed down application in my basement to drive the ventilation dependent on humidity, co2, dust and outside conditions (fully node red controlled). Yet this has nothing to do with “smart metering”