I have installed a grid-connected PV system (but not feeding back in to the grid), with battery storage and ESS, for a mix of back-up and self-consumption.
I am using multiple instances of the Programmable Relay Assistant to control water heating via the MultiPlus' secondary programmable relay K1, by:
- turning it on when insolation rises to a certain level (measured via a small PV panel's output current feeding a Schmidt trigger, which in turn drives a MultiPlus Aux input) AND AC load below a certain level AND SOC above a certain level, and
- turning it off when any one of the three parameters reverses to a lower / higher value (i.e. with hysteresis).
One particular question is about AND / OR logic - it appears to me that:
- when more than one condition is set in the one assistant, then it uses AND logic, and
- to implement OR logic, it is necessary to use multiple instances, each with one condition.
Can anyone confirm from experience or product info', that these are correct?
I understand that the order the Assistants are listed in, in VE Configure, affects how they operate, and that those lower in the list 'override' those higher in the list. I found that my system works approximately as I want when the 'switch on' Assistant is at the top of the list. If I move it to the bottom of the list however, then the K1 relay appears to remain on permanently, irrespective of inputs, and I don't know why that should be.
I'd be grateful for any more specific / exact information about how the ordering of the Assistants functions.
When I tested control using either one of the Aux 1 input or AC load (one at a time only), they behaved perfectly, including with the delay times. However, when I combined the two in one 'turn-on' Assistant, it then appeared to ignore the delay times, and switch on instantly when both conditions were met. Any ideas about what might have caused that?
Finally, with all three inputs combined in one 'turn-on' assistant, with 'AC load lower than 1250W', I had it switching on when AC load was still around 2500W, so either it is not actually AND-ing the inputs, or the parameter is not working correctly.
Does anyone have information about exactly what the 'AC load' parameter reads?
Thanks in advance!