Hi and thank you for your question. I’ll try to answer it as best I can.
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My Calculation Flows has two goals. Firstly, to smooth the solar power excess value, by averaging the last two minutes every 2 minutes, and then putting the result into a variable (in this case the Insight W I/E w/o EV variable). So every 2 minutes, this variable is updated. Then, in the Solar Charge Flows, the change of this variable is picked up at the beginning of the flow, which triggers or not the charge, respectively an adaptation of the charge amperage. I could have done all this in a single flow, but I preferred to separate the two. The second purpose of Calculation Flows - and this is a very important point - is to cancel the increase in house consumption when the charging station starts charging. Let’s take an example: if the solar power production is 3000W and the house consumption is 600W, there’s a surplus of 2400W that can be sent to the car. So the charging station will start charging at 10A (approx. 2300W), but the house consumption must not rise to 2900W (2300+600) because of the start of charging, otherwise charging will stop again immediately because Homey will think there’s only 100W left, whereas there’s still 2400W left. This element of the calculation is therefore very important, and perhaps also answers your second question.
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If solar production and home consumption (excluding charging station) are stable, there’s no reason for the charging rate to change constantly. It will be re-evaluated every 2 minutes, but generally it rises gradually and then gradually falls again. If it continually yo-yo’s with a difference of several hundred watts, there’s a problem.
Don’t hesitate to ask me more questions. Personally, I’ve been using these flows almost every day for several years now. The calculations can certainly be done in a totally different way, but in a way, you still need to know how much energy is available and can be sent to the car. On the other hand, this value must have a certain stability. I wouldn’t want my charging station to potentially adjust its amperage every 5 seconds.