Feature: zero feed in (when energy prices are negative)

[hyperbart]

Is your feature request related to a problem? Please describe.
In the Netherlands and Belgium negative energy prices or put in other words “having to pay to put your PV power on the grid” is becoming more and more prevalent.
EVCC is currently the only (HEMS) tool enabling us to steer significant/worthwile consumption to cheaper hours and auto consume our PV power as much as possible.
EVCC is the “last system” and most global system in line and determines the excess on which it can decide what to do with it.

Hence, why not have it decide if and how much excess energy there should be and most certainly when the user will be penalized for delivering energy to the grid while there is already an abundance of PV/green energy.

Describe the solution you'd like
Have EVCC control the PV output during certains periods.

Describe alternatives you've considered
Victro VRM, but not compatible with SMA inverters.

[RenatusRo]

💚 indeed, only the (fading out) groenestroomcertificaten are withholding us from switching off the PV on sunny sundays.

[andig]

So what would "zero feed in" controller mean?

[hyperbart]

So what would "zero feed in" controller mean?

A template mechanism (just as with the charging points or solar inverters) via modbus/protocol which allows EVCC to control the power of the inverters in your household.

A control loop that checks if energy injection tariffs are above/below a treshold, if this is the case and no car is charging it will throttle the power output to something a little above the necessary power in the household.

Example:
No car is charging, and user sets treshold to negative prices
If negative prices are active EVCC checks power consumption of the house, EVCC checks how much the home battery is charging and can charge maximum, if home battery can not ingest all power then PV inverters are throttled to something a little bit above the zero on the meter principle (definable value).

[tbiest]

As an addition to this idea: it might also be that the heatpump is charging with PV surplus but cannot consume all the PV energy. It then would be also good to "dim" the solar panels to just above 0 as mentioned above. This is also a solution for the "terugleverboete" in The Netherlands: you will get charged for every kwh that you feed to the grid.

When the charger can consume more or if you for instance plug in your EV, the "dimming" of the PV can be reduced or cancelled.

[hyperbart]

As an addition to this idea: it might also be that the heatpump is charging with PV surplus but cannot consume all the PV energy. It then would be also good to "dim" the solar panels to just above 0 as mentioned above. This is also a solution for the "terugleverboete" in The Netherlands: you will get charged for every kwh that you feed to the grid.

When the charger can consume more or if you for instance plug in your EV, the "dimming" of the PV can be reduced or cancelled.

You can cover this by setting the price to a high number, my feature request/logic would never reach said price and thus always provide NOM/zero on the meter then. That’s the beauty of it 🤩

[andig]

See #19715 (comment) for related apis.

When the charger can consume more or if you for instance plug in your EV, the "dimming" of the PV can be reduced or cancelled.

The primary approach would be to limit feed in to a fixed value (zero). The inverter will maintain this value and dimm production. The true challenge here, similar to battery boost, is scaling the loads up when there is no consumable feed-in.

It might make more sense to dimm feed in to at least the minimum step size for scaling any available charger up (e.g. 3p x 1A x 230V for a charging charger or even x6A for a disabled charger). This party is fiddly imho.

[hyperbart]

See #19715 (comment) for related apis.

When the charger can consume more or if you for instance plug in your EV, the "dimming" of the PV can be reduced or cancelled.

The primary approach would be to limit feed in to a fixed value (zero). The inverter will maintain this value and dimm production. The true challenge here, similar to battery boost, is scaling the loads up when there is no consumable feed-in.

It might make more sense to dimm feed in to at least the minimum step size for scaling any available charger up (e.g. 3p x 1A x 230V for a charging charger or even x6A for a disabled charger). This party is fiddly imho.

The inverters are able to scale down to almost 0W if needed. Can you explain to me/us why a minimum of 6A should be injected? When a charger wants to enable, wouldn't it be possible to ramp up an inverter or multiple inverters, check if there is enough surplus and then activate charging according to the proven/well known logic which we are using now?

[andig]

How do you know a charger „wants“ to enable in PV mode? The whole definitionnof PV mode is that it enables on surplus. Which you don‘t have in this case.

[tbiest]

You know that it is dimmed, and you know the maximum capacity of the charger?

[hyperbart]

@andig good point. One could solve this by not working with a static zero value but with a variable to be set. Depending on the enable/disable values one should accept that this feed in value is equal to the enable values or accept that the charging point would not enable.

An alternative would be as @tbiest was referring to (if I understood him correctly) where you would check

If PV mode == true and SoC is below SocLimit then open dimmer to provide more than 6A

[tbiest]

Why not make it simpler: have all the evcc chargers to work (start/stop/increase/decrease) based on a non-dimmed PV value so they don't get influenced by the dimming. And then decide to dim the PV based on the actual grid feed-in value.