Cheaper charging while making use of PV-energy

[krispek]

These days my PV panels do not generate enough power to exceed the minimum threshold for PV-charging. However, at minimum speed, a significant part of the power required for my car would be generated by my solar panels. In addition to that, electricity is already getting cheaper during the day because of the sheer amount of solar installed in my country (The Netherlands). And since we receive less money for energy delivered to the grid than we pay for energy taken from the grid, I see an opportunity to save some money.

Given this, it is cheaper to charge my car at minimum speed at day, than to charge the car at full speed at night when electricity from the grid. Would it be an idea to adjust the charge planner for this? EVCC could for instance take the average charging price per kWh from the charge planner. If the price at minimum charging speed is significantly lower, the car could start charging at min+PV mode. This further reduces the cost of charging for the 'cheap charging' strategy.

I searched for this functionality in other discussions, but couldn't find something like this. This might be caused by my lack of knowledge of the German language. :)

[timnussbaum]

I also have the same use case. I am located in germany with dynamic prices via Tibber. My pv power is also too low to use the standard PV mode - it peaks to max 800/900 watt - with a base load of about 200-350 watt I have around 200-600 watt left for charging. I think there is not exactly a feature which makes this price calculation based on pv generation, but with another feature the same result can be reached - in my case. Just give it a try.
I make use of the feature "enable/disable" under the loadpoint section. See FAQs for more detail: https://docs.evcc.io/en/docs/faq#with-enabledisable
During sunny days my dynamic price is also quite low (and will even get lower in the next time) and I can cover 25-35% from my own pv. With the lower price during this period and a pv share of about 30% the price is around 20-23ct per kWh which is quite good. During the night I do not get under 29ct.

Here is my config. I takes a bit of time to find the best values for my use case but this works just fine.

loadpoints:
  - title: Garage # display name for UI
    circuit: lpc
    mode: pv
    enable:
      # activate if 200 watts are fed into the grid for 4 minutes
      delay: 4m
      threshold: -200
    disable:
      # disable if 1050 watts are consumed from grid for 6 minutes
      delay: 6m
      threshold: 1050
    charger: wallbox_garage
    vehicle: ioniq5_2025

[krispek]

Thanks, I’ll give this a try. Do you know whether you can dynamically adjust these values, for example via MQTT? In that case I can make a calculation in Node-red and build this feature myself.

[timnussbaum]

I don't use it but should be possible via MQTT or REST. See docs:
https://docs.evcc.io/en/docs/integrations/mqtt-api#loadpoints

[StefanSchoof]

Please keep im your calculation, that at loading at the minimal current you load with the least effencency. So you need more kWh to get the same kWh into your car.

[timnussbaum]

Good point to keep in mind. For me its still "better" as I would give away my pv energy for free because I do not have a feed-in tariff in place.

[krispek]

Agreed. :) That’s why I stated that the price should be significantly lower. However, this makes it also harder to implement: what is significantly less?