Export sensor and relay module (no immersion for surplus use).

[ukzerp]

6.3kW PV array. 12.4kWh battery bank. Combi boiler, so no hot water tank.
Surplus energy variable voltage diverters to immersion heaters make sense, but not if you don't have an immersion heater!
What we do have is a PHEV with ~2.3kW "granny charger" (7kW charger not needed as battery not huge and we're home a lot and somewhat counter productive with UK low sloar export W values). I could sit and watch my App all day and switch on the charger when exporting more than, say, 500W or, if I lived in Australia fit one of several available devices (EG Catchsolar relay) which can trigger a relay whenever a user defined export W value is reached (also includes anti-rapid cycling functions).
I can't find anything available like this this in the UK.
The market for such devices are obvious, but nobody appears interested.
Does anyone know of such a device available in the UK?
Thanks.

 

[johnb2713]

So all you really want is a relay connected to a current sensor (amplitude and direction) so that when your export exceeds say 6amps the relay is energised and remains energised until the export becomes 0 or less?
Several solutions spring to mind dependent on your tech know-how / willingness to learn - Arduino with a CT connected, Home Assistant (my preferred option) or 'if this then that' (https://ifttt.com/).

 

[ukzerp]

Thanks for the reply.
Always willing to learn.
One thing that will reinforce my woeful level of ignorance is that I've no idea how the input from a CT could differentiate between 6A AC being imported and 6A AC being exported.....

 

[ProDave]

There are aparently a pair of wires in the charging lead that tell the car what rate to charge at. I know one person that built his own variable rate charger that was linked to his PV so it tried to match charging rate to surplus PV rate. It worked, with the limitation that there is a minimum charge rate the vehicle charger can go down to.

I can't post the details as the forum it was on closed down and I have lost contact with him.

This will no doubt be the feature the Australian devices are using. Why not just buy one? I would not be concerned if it does not come with a CE mark for instance.

 

[ukzerp]

Thanks for the reply.
I have tried to purchase an Australian device as this would be by far the easiest solution and wouldn't even need hard wiring in my application, but nobody is willing to export to the UK

 

[johnb2713]

There are aparently a pair of wires in the charging lead that tell the car what rate to charge at. I know one person that built his own variable rate charger that was linked to his PV so it tried to match charging rate to surplus PV rate. It worked, with the limitation that there is a minimum charge rate the vehicle charger can go down to.

I can't post the details as the forum it was on closed down and I have lost contact with him.

This will no doubt be the feature the Australian devices are using. Why not just buy one? I would not be concerned if it does not come with a CE mark for instance.

I designed and built my own charger, you would need to adjust the duty ratio of the pilot signal to change the charge current, minimum is 1.4kW with most chargers - 6 amps.

 

[johnb2713]

Thanks for the reply.
Always willing to learn.
One thing that will reinforce my woeful level of ignorance is that I've no idea how the input from a CT could differentiate between 6A AC being imported and 6A AC being exported.....

You do it by comparing it to the AC voltage, if the CT is negative = export, +ve = import or vice-versa.

 

[johnb2713]

Thanks for the reply.
I have tried to purchase an Australian device as this would be by far the easiest solution and wouldn't even need hard wiring in my application, but nobody is willing to export to the UK

Do you have a link to the device?

 

[ukzerp]

Here....
https://www.catchpower.com.au/catchsolarrelay

 

[coulter]

Hi,
Have you considered the Shelly EM, sounds like these units can be configured to monitor and control surplus export to the grid.
https://shellystore.co.uk/product/shelly-em-50a/

 

[Joules]

...Does anyone know of such a device available in the UK?
Thanks.

A couple of years ago I came across an expats Sway article called Using an Immersun to Automatically Solar Charge an EV which you might find of interest?

What took my interest was that back in 2014 I had bought an Immersun Mk II but now use it to dump excess solar power in a zero-export arrangement to a storage heater simply because I have not managed to find a way to use its variable amplitude 50Hz sine wave output power to usefully charge a battery.

The user manual describes a feature called a Multifunction Relay with SPCO contacts which can be used for a variety of things one of which is to operate when Immersun output or export power as they call it exceeds a settable threshold in my case 200W.

Take a peek, these units today don’t come cheap.