PV export control - PV traffic lights

[Carrerahill]

I know some members on here have done things like this before, so I am looking for a little guidance. I want to make a sort of PV traffic light system which I can in turn use to control some loads.

 

We do not have a cylinder so an iBoost is of no use to me, but what would be of use to me is a monitor that can switch on outputs or give us a bit of a heads up we have some spare PV to make use of. 

 

My thinking is the best way to do this would be an Arduino monitoring a CT meter or meters (mains incomer and PV), it can monitor what is going on and I can then write some code to carry out different tasks at different thresholds. Let's say I had a spare kW, I could kick in the water heater in the garage or something. 

 

I am aware things can probably be bought to do this sort of thing, but there is no fun or learning in that and as I see it the less I spend on the PV related components the better the sooner the payback! 

Edited April 20, 2023 by Carrerahill

[S2D2]

Check if your inverter has a local API you can call via HTTP, then you can get your export power reading for free.

[Carrerahill]

12 minutes ago, S2D2 said:

Check if your inverter has a local API you can call via HTTP, then you can get your export power reading for free.

It has all these things and live monitoring via a portal etc. so I suspect that can be used indeed. Just need to tie it all up.

[S2D2]

16 minutes ago, Carrerahill said:

It has all these things and live monitoring via a portal etc. so I suspect that can be used indeed. Just need to tie it all up.

Can't speak for other manufacturers but the Solax portal is only updated every 5 minutes, so useless for export logic. There is a local REST API that can be called to get live data though, I call mine every 10 seconds to log the values so much better for control systems. Your Arduino can then call this rather than querying a separate CT clamp.

[SteamyTea]

It is easy enough to could the LED pulses on the generation meter, then set a limit that you divert at.

But where are you going to divert to if you do not have thermal or chemical storage?

[Carrerahill]

3 hours ago, SteamyTea said:

It is easy enough to could the LED pulses on the generation meter, then set a limit that you divert at.

But where are you going to divert to if you do not have thermal or chemical storage?

I am going to work on that! I have some unconventional ideas.

 

I am now thinking I need a little cylinder which I would use to preheat water going into the combi, or I might use it to charge a battery bank in a more unconventional way, i.e. a battery charger that gets powered up when export meets or exceeds typical charger demand - that sort of thing. I have a 24VDC PV system in the garage which as of yet has no load on it (only got the solar charge controller 2 weeks ago) which I am going to use to feed a small inverter and run all my garage lighting and garden/house external lighting from, so I have options.  It is as much about tinkering for me as anything else. 

 

 

 

 

 

Edited April 21, 2023 by Carrerahill