Ways of having sockets live only when generating PV power 13 September 2022 at 10:48PM in Green & ethical MoneySaving 18 replies 492 views

Skintsaver

I'm looking into a way of powering some sockets to charge items when the solar is generating. 

The only way I can see how to do this is using a ct clamp like this on the meter tails

https://myenergi.com/product/ct-clamp/

Then wiring to the A1 A2 terminals of a 230v contactor.

Would the CT clamp close the contactor when exporting power to the grid?

I'd also like a 2nd feature where when my panels are producing 600w+ then my electric towel radiator will turn on. But I guess a 2nd clamp would do this? If they trigger at different amps. 

Or have anyone else done something similar but a different way. 

Spies

You could do it the smart way, my Solax inverter allows local access to the 30s generation data, I then then create an automation that turns on smart sockets if the condition is true that generation is over a certain amount.

I do this with my washing machine - so more often than not, I don't get any grid pull when the water is heating.

If the items you have don't have plug sockets, you can get shelly smart switches that will sit inside the wall box. 

Skintsaver

How do you create a automation? I'm a complete novice with smart things. But it could be better if I'd want a socket elsewhere later on doing it your method. I have a Solis S6 2.5kw mini inverter with their data logger, not sure if I can do somthing like you have with mine 

Spies

I use a piece of software called Home Assistant, there's various plugins you can add, I'm not sure if the Solis works out of the box with it.

Tplink Kasa plugs work out of the box so they're controllable via the automations you can create.

It might be a little more involved than you had hoped so maybe someone else will be along with another suggestion soon. 

Reed_Richards

Spies said:

You could do it the smart way, my Solax inverter allows local access to the 30s generation data, I then then create an automation that turns on smart sockets if the condition is true that generation is over a certain amount.

I do this with my washing machine - so more often than not, I don't get any grid pull when the water is heating.

If the items you have don't have plug sockets, you can get shelly smart switches that will sit inside the wall box. 

But presumably the sockets stay on if the sun goes behind a cloud and the generation drops below your trigger level?  Or does your washing machine grind to a halt?  

Spies

Reed_Richards said:

Spies said:

You could do it the smart way, my Solax inverter allows local access to the 30s generation data, I then then create an automation that turns on smart sockets if the condition is true that generation is over a certain amount.

I do this with my washing machine - so more often than not, I don't get any grid pull when the water is heating.

If the items you have don't have plug sockets, you can get shelly smart switches that will sit inside the wall box. 

But presumably the sockets stay on if the sun goes behind a cloud and the generation drops below your trigger level?  Or does your washing machine grind to a halt?  

Yeah they stay on, I'm not going to cycle my plugs on and off mid cycle every 30 seconds. 

paul991

you would need the relay and sensor board too

Heedtheadvice

You can not just use CT clamps. They are just a part of a sensor and measurement system and are used to couple circuit current values into other equipment.

There is no reason why you canjot design and build a monitoring and switching circuit to do what you wish but suggest that, as you ask just a basic question, it could well be beyond your ability to produce and be safe?

No harm in learning though but jumping into mains power control is several steps to far at this stage given the complexity of requirement and safety issues.

I have designed such similar equipment in the past but nevertheless plumped for comnercial off the shelf stuff for lots of advantages. The controllable switches are good for that end of things but what you desire for different levels of switching and measurement interfacing will require other equipment and programming skills most likely.

See if others come up with more ready made devices that meet your desires but be prepared to pay....and where the cost might outway any benefit!

thevilla

The Apollo Gem solar diverter ( no longer available) has an option to switch a supply on when a defined solar surplus is available, rather than ramp it up as the surplus increases.  I'm not sure if there are similar products.

If you enjoy tinkering I'd agree Spies option of Home Assistant is a great way to go.  I do similar with a raspberry pi running a script to turn on the dishwasher but HA offers more flexibility and integrates with many commercial products including inverters and sockets.

 https://www.home-assistant.io/

Skintsaver

I'll have a look into home assistant again. I'm just after somthing that's simple and will work. I think smart things can over complicate things. Was certainly the case when I geofenced my phone so my heating automatically came on after leaving work! 

Obviously don't want to spend a fortune on the materials needed. paul991 said:

you would need the relay and sensor board too

Thanks, This is what I thought. Wernt sure if a ct clamp would operate a contactor with volt free contacts or not. Its somthing I've not installed before but should be straightforward for me to do. 

Ectophile

A CT only measures current, and produces a relatively tiny output.  By itself, it's not powerful to turn anything on or off.  You would need some circuit that would measure the current reported by the CT clamp, and decides when is a good time to turn on the socket.

If you want the thing to behave in a useful way (not turning the power off in the middle of a wash), you will need something fairly smart,