Using surplus PV Power - best algorithm?

Has anyone got a good "algorithm" for this - assuming one has adequately sorted out  Power monitoring & TRIAC control of, say power to the Immersion Heater, how should the system cope dynamically ?

Thus, with 3kW PV power and House using 1kW, then we slice up the surplus 2kW into our 3kW Immersion Heater.   The monitoring system then "sees" the house using 3kW, but taking nothing from the Grid, so all is well.

Then a cloud comes along - PV power drops to 2kW and, say, someone switches on a 500W towel rail - so the situation is PV = 2kW,  the house is now using 1.5kW. so only 0.5kW can go to the TRIAC system - but the power monitoring system does not know the difference between all these different loads so cannot adjust the surplus power "slicing".

It seems to me that a Surplus Power system can only work if "periodically" the TRIAC is switched off and the house power monitor can see real loads and calculate the surplus which can go to the Immersion Heater.  So maybe one works on a cycle of, say, 10 seconds TRIAC operation, then off for a few cycles to test the "actual" load situation, recalculate, then run TRIAC for another 10 secs.  Maybe one can monitor in between the TRIAC power cycles.   Any comments ?

PaulOckenden's picture

Re: Using surplus PV Power - best algorithm?


Best algorithm in the business, and used by many.


Robert Wall's picture

Re: Using surplus PV Power - best algorithm?

The "best" algorithm is the one that suits your needs. Define exactly what you want to achieve, then all should become clear to you.

If your requirement turns out to be exactly the same as calypso_rae's, then you should probably use his algorithm. It is thoroughly researched, tested and proven. If your requirements are different, it's up to you to come up with your own algorithm. Nobody will blame you for having different needs.

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