PV Diversion strategy

Applications
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1

I’m about to get a PV diverter set up. However we don’t use a lot of hot water and so I’m considering what other devices to divert to. What do others do?

We have a gas boiler and 200 litre hot water tank.
Economy 7 electricity which I use to charge my Nissan Leaf. However it’s rarely plugged in during the week.
We use a dehumidifier for drying clothes (which is currently a manual partial “divert” in that I leave on if it’s going to be at all sunny)
I’ll get an electric panel heater for anything left.

So the rough “strategy” in terms of diversion priority is:

  1. If available power >2500W then charge the car (10 amps)
  2. If humid and available power>250W then switch dehumidifier on
  3. Divert the rest to Immersion heater
  4. When hot water heated then divert to a panel heater in the hall

1 and 2 will be implemented using EmonPi and OOK 13A plug switches (must admit I’ve not even looked at the coding for this yet)
3 and 4 handled by an Arduino+2 Triac output stages

Does this make sense?

Many thanks!

2

What will happen when the amount of surplus power suddently drops, such as when a kettle is turned on?

You may be interested in this thread:
https://openenergymonitor.org/emon/node/5391

3

Thanks Robin, lots to think about, that’s a useful thread. I’ll get the immersion divert going and think about it over the winter, as I’m unlikely to have too much excess.

4

So, last night I finally found the time to get my diverter finished and tested - and it works! In my shed at least.

Very satisfying, and hats off to everyone involved.

I used an emontx shield on an Arduino Uno, and a Crydom Solid State Relay. I did try the cheapest solution, a triac, but couldn’t get it to work.