DIY Arduino based solar PV dump controller

[ProDave]

Well my 433MHz transmitter module arrived from China today.  Powering it up on the bench I see it consumes 5mA at 5V so I should be able to power it directly from an Arduino output that can source up to 40mA.

 

I just need to wait for the receiver now which hopefully won't be long now.

 

[ProDave]

And today the 433Mhz receiver arrived.  It paired to my chosen transmitter code without problem.  So now to add them to the PV dump controller.  Watch this space.

[ProDave]

That's the 433MHz transmitter integrated into the dump controller.

 

I was going to mount the receiver with it's relay into one of my portable convector heaters, but can't see any easy way to do that.  Instead I am going to make it more general purpose in the form of a wireless controlled switched extension lead.  Simply a double 13A socket mounted in a 47mm deep back box that will have enough depth for the 433MHz receiver module and a small 12V power supply to feed it fitted in the bottom of the deep back box.

 

Of course I didn't have a suitable little 12V power supply so that is now on it's way from Hong Kong.

 

I did the "car test" and find when the transmitter is energised, now it is in it's final location, it does affect my car key fob slightly, but only in so far as I need to be closer to the car to make it work than normal.  I can live with that.  (When I had it on test on the bench, further away from the car, it didn't make any difference to the car keyfob range)

 

I will need to quietly do the same test with SWMBO's car when she gets back....

EDIT:  Tested, hers is not in the least disturbed by this 433MHz transmitter so should not be any "issues"

[ProDave]

 last bit arrived from China today, so that's my RF switched 13A socket completed.

 

 

Bottom left is the £1.54 433MHz receiver with relay output,    And bottom right inside the white box is the £1.49 12V power supply.

 

I have tried it and it works, but now the solar PV output is well on it's way down the "winter cliff" I don't think it will switch on in anger now until the spring.

[SteamyTea]

34 minutes ago, ProDave said:

 

 last bit arrived from China today, so that's my RF switched 13A socket completed

 

You going to put up circuit diagram, code and parts list.

[ProDave]

Early home from work today, sun shining, heating off, no appliances on. I noticed the immersion was running at 100% so no doubt some power being exported as well.  So time to plug this in and test it (I have always wanted to be present during initial testing)

 

It is working well.  when immersion power nears 100% it turn on my RF controlled relay, turning on a plug in panel heater on it's 700W setting. That turns off again if excess gets too low.

 

So 700W going to a panel heater and still near 100% to the immersion.  It is doing it's job of using up a bit more otherwise "wasted" surplus.

 

I can plug the heater in anywhere with it's RF controlled relay. Currently it's giving a little heat to the plant room above the garage that normally has no heat.

 

It will only be of use in the shoulder seasons, I would not want / need to dump to a space heater in the summer.

[Stones]

In our last house, I had a hard wired heater set up from PV diverter (immersion took priority via volt free contacts due to the complicated way the immersion was controlled).  I used an old storage heater rather than convector and found it very useful in the shoulder months.  Even relatively small amounts of input were noticeable in terms of heat output.  I used an isolation switch with neon indicator and it was really interesting to see it flickering away according to the amount of electricity being diverted to it, barely a flicker at some times, full intensity at others.

 

In the summer as you have indicated, it was surplus, but given you have a portable set up, could you potentially use the heater in the garage for speeding up the drying of laundry?

[ProDave]

Or I could put the heater outside out of spite rather than export it for free.

 

I like the idea of a storage heater, but not very portable.  e.g I might put the portable dump heater in the utility room under the clothes drying "pulley"

[SeanK]

On 13/03/2020 at 17:52, ProDave said:

Or I could put the heater outside out of spite rather than export it for free.

 

I like the idea of a storage heater, but not very portable.  e.g I might put the portable dump heater in the utility room under the clothes drying "pulley"

 

Would love to know how you're getting on with this!

 

Had always thought diversion units had to have grid connection, but after a search seems that's not so! Some off the shelf alternatives:

An Australian unit - https://www.ecocool.com.au/products/hot-water/plasmatronics-jackal-hot-water-system-power-diverter/

And one in the UK that apparently works off-grid - https://www.earthwiseproducts.co.uk/solic-200/

Just finding out if these units can work in multiples....

[ProDave]

Resurrecting this old thread.

 

I have encountered an issue.

 

Above i describe the 433MHz remote control switch for my additional dump heater.  Well it upsets the operation of my car key entry / imobiliser system.

 

This has been a minor issue for a long time, but when the dump heater is on it just desensitised the receiver on the car, and I had worked out where on the car the receiver was so you just held the key fob close to that point.

 

Well now I have a new car, and this afternoon when the dump heater was on, the car would not unlock and I could not find a sweet spot where the key fob would work.  So I now have to find a solution to a problem I have been ignoring.

 

Ultimately I might look for an alternative radio control transmitter / receiver pair, either one that does not leave the tx energised all the time, or one that does not use 433MHz.

 

To find an immediate work around I am going to implement an extra switch input that will disable that extra radio control heater and do so for a timed period say 10 minutes to give me time to go and get in the car and drive away.

 

[Temp]

Depending on  where things are located a screen of aluminium foil between the tx and car might be worth trying.

 

Or perhaps fit the Tx with a more directional antenna?

 

Think you can also get some stuff on the 863MHz band but check your burglar alarm doesn't use that band?

 

[Radian]

To signal the firing of my immersion control TRIAC I use ESP now  which sends packets over 2.4gHz with extremely low latency. Low enough to be sent every mains cycle.

[ProDave]

10 hours ago, Radian said:

To signal the firing of my immersion control TRIAC I use ESP now  which sends packets over 2.4gHz with extremely low latency. Low enough to be sent every mains cycle.

In my case the remote dump heater switch is a dumb device.  I bought a radio controlled relay and transmitter for it operating on 433.975 MHz.  I had hoped it would be "better" than it is and only transmit a code to turn the relay on and again to turn it off.  Instead it was rather disappointing that it transmits continuously whenever the relay is on.  It blocks my Subaru key, but oddly enough not the Toyota key of my wifes car, even though both use 433 MHz.

 

A simpler solution might be just find a different wireless remote relay to use which does not transmit continuously.

 

For now, my disable switch works.  I can either disable it totally, or disable it for 5 minutes (to give me time to get in the car and drive away)

 

It's a good security device, nobody could pinch my car even if they had the key.