Reverse flow, sometimes called solar diverter switches

Hey @Colin Wheeler,

I’ve moved this topic to the Smart Home category to see if it gets more traffic!

Hi  Emmanuelle,

Thanks for message, I didn’t really know what category to put it under but Solar PV seemed the most logical. Will be interested in any responses.

Do you know if there have been any previous posts over the last two years or so on the subject as these might be relevant.

kind regards C

Hi @Colin Wheeler,

We have loads of solar customers here that I can reach out to. I will start off with @BPLightlog as he really is so knowledgably with this solar stuff.

Also we may be have a topic already that I can link you to, but I don’t know as my own inexperience has me unsure if your question. What is reverse flow switching? 

@Colin Wheeler

If you type "solar diverter" into the forum search bar you will find a few threads. For example.

Some are quite old so you will have to hunt for recent posts. You could then tag those posters in this thread so they are more likely to see it. Some of the posters won't be around on the forum anymore, so it will be a bit hit and miss. 

You might find some useful info searching "solar 3 phase" as well.

You could try this forum if you haven't already for discussions on diverters, batteries, wind, hydro etc.

https://renewableheatinghub.co.uk/forums

Morning Tim,

I would value a communication with @BPLightlog as I understand he has both Solar and wind so would be interested in a conversation around those topics.

Secondly you asked about reverse flow switching. 

These devices measure reverse flow in the incoming wires to a property and compare this with solar output, if there is excess above certain thresholds set by the user then the excess is diverted to, usually an immersion heater for hot water. Once the hot water needs are satisfied the immersion thermostat switches the load back to export to the grid. The system is not restricted to only immersions it can support general power requirements for a property as well. There are several manufacturers of the devices.

I would advise any one considering adding solar panels to their property to get the installer/electrician to fit one of these, It is easy to do on single phase at the moment a bit trickier with three phase but can be done!

In my case with nearly 50 Kw of solar power and being an annual net exporter to the grid and with the very large differential currently between Import and export prices It makes economic sense to invest in equipment to divert as much of the power, I currently export, to heat all of my hot water and underfloor heating needs.  

  Sorry for the longish reply on this subject, you may wish to add this topic to more than my original question as it concerns solar panels, 3 phase, and electric water heating/boilers etc.  

regards C.

Morning Jeffus,

Thanks for your interest, I have read The Tutorial provided by Hydrosam.

I am currently considering adding switching to my Power system here as the recent rises in price of imported power to my all electric property make this very viable cost wise.

As hydrosam pointed out these units are relatively cheap and easy to install on single phase systems. My problem is I am all 3 phase at the import export part of my property, as is my heating and hot water system. My home  also has its load spread across all 3 phases to maintain system balance.

As was pointed out in the article adding these units might seem selfish and perhaps is so if solar panels are installed freely as part of government grants or incentives. However we had to match fund our investment in our installation with the projected returns , with the  recent rise in prices not matched by increases in revenues we have to do as much as we can to keep up! 

I shall do as you say, continue searching for information both here on the Forum and elsewhere, Thanks again for your intersest. 

Kind regards C. 

Hi @Colin Wheeler , apologies for the delay. Just trying to catch up after a family break. 
 

Let me see if I understand your question. There are several devices which look to use excess solar generation - I actually don’t have one but use the storage batteries to soak up and deploy the additional power. 
From what I understand, as you mention, there are diverter systems which can enable a water heating ‘storage’ to use any excess. There are several who I’ve noticed using these. 
The whole point about maximising your solar (and any other) generation is being able to deliver it in the most useful way depending on your situation. 
For 3 phase systems, it gets a little more complicated as it will need some intelligent monitoring to see where any power draw is being made and deliver to that specific phase. Again, there are threads associated with this although not as many. 
Hopefully we can understand your situation a little better to feed back to you. 

Afternoon @BPLightlog 

Thanks for the contact, To give you a bit of an insight, when we set out to convert a barn on our farm in 2010 to become our main residence, we decided we would do what we could to make it as cost effective as we could, naturally, so we under took a great deal of the work ourselves.

At a very early stage it became obvious that energy prices and the green issue were going to take precedent, we investigated several options, Ground and air source heat pumps, solar both PV and thermal, battery storage ( very much in its infancy in 2010) and wind.  Having ruled out ground source heat pumps on cost and air source on, not very effective for the property we would eventually make ( Even with masses of insulation.) We decided with input from various specialists that our best option at the time would be Solar Pv and and an all electric arrangement. We installed 49.3 Kw of solar panels on a ground mount in 3 arrays in the field next to the buildings as this allready had a 3 phase power line overhead so grid tie although costly in terms of transformer installation made sense.

The upshot of this is now with all this lovely power and rising input/low export values we are maximiseing our usage with judicial manual management. Currently we have a 24Kw electric boiler feeding Hot water and underfloor heating tanks, last year we added solar Thermal evacuated tubes into the mix  and as I currently think Battery storage has a long way to go until it becomes cost effective, we would need a very large air source heat pump to run our system (which we are advised would use more energy than our current set up) we started to look into back flow ( Reverse run) switching, mainly to automate our current manual operation.

The difficulty we are running into is that currently most of the switches are designed for single phase, the options for true 3 phase are limited, as these units operate the sensor on one phase it needs net metering to really do the job and most meters don’t support net metering. As our immersions are 3 phase as well as the boiler being 3 phase we would have to install additional relays to the output of the switch to control the 3 phase contactors, not too much of a problem but a lot of the switches only have two resitive load outputs and these are limited to around 3.6 Kw 

I am in contact with one company who are working on a 3 phase unit but they say they are some way off!

I therefore wondered if some of OVO’s Tech savvy customers might have allready solved some of the issues we are seeing., or an insight into other solutions.

I have lots more thoughts around the subject but thats enough for now.

Thanks once again for contacting me and look forward to any input you have.

Kind regards C.    

I hope someone might be able to help but I’ve not enough complete knowledge to help much unfortunately. 
I have been involved in a site which sounds a little similar to yours but they eventually went with a ground source heat pump with underfloor heating and solar PV. 
They are just installing a further 38 panels on a barn conversion on the same site and are working with a polyphase AMR meter which is net metering (as you say, needed for such a set up). The ‘almost’ smart meter was installed by National Grid as their supply company could not help and I have specified the new PV system to be integrated and ready for battery storage in due course as in my own view, batteries give good support to solar to get effective energy - even if on their own, batteries don’t quite give as good a return if you consider them separately.
I’ve not seen many using the technology you are looking at but as I said, hopefully someone can help. On the switching needed, it might also be worth discussing with your DNO as they regularly switch HV equipment. 
Good luck !

Good evening, @BPLightlog 

Thank you for getting back to me, Very interested in what you say about about the site you are speccing. I would be interested in which model of AMR your client has. We also have a polyphase AMR meter provided by Western Power ( Now part of National grid who are our DNO.) same situation, that SSE could not supply at the time. From what I can glean, though the meter might be capable of net metering the supplier also has to be! Is this your understanding?

We were recently migrated to Ovo from SSE and have run into a problem that Ovo do not recognise this meter as being even semi “smart” and as they have decided to not have a system for remote reading of these units, Which SSE did in part( Export),  we are  running into communications issues.  Not Prying, will your client be claiming fits? if so I guess they will be under SEG tarriffs, so should be ok. If they will be 0 threshold for export due to battery storage then I guess export issue will not arise unless they exceed battery capacity. 

If I manage to take this forward will you be interested in the detail?

regards C.