@david999 Scottish Power off peak 7p (mn - 0500, which annoyingly I have to adjust on the inverter when the clocks change) 28p peak 68p/day standing charge.

Using most of the charge through the day - so let's see what the cooler temps bring once the heat pump is running 24/7 😟

@bretix this is my proper test year, next year whack more panels on my garage roof.  I put loads of insulation in the house since it was a rebuild so heat loss is at minimum.

@transparent yep that's another project I'm working on. UV protective lagging for outside as well as sorting out the insides. I'm planning to 'box' off the plant room too...

Returning now to earlier (long) list of issues raised by @bretix

Posted by: @bretix

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my intention is to keep the batteries topped up and trickle feed the hot water cylinder/ev

Although @david999 suggested using the Eddi Diverter, this isn't necessary in your case.

You have a SunSynk inverter.
It has this Solar Diversion facility in-built as standard.

The Auxiliary power Connection is usually regarded for use as an input from a generator.
However, you can use the Advanced Settings menu and define it as a mains output.
You configure the criteria within which it will be activated.

Look at p.63 of your Installation Manual:

Posted by: @bretix

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I'm assuming I can't get retrospective MCS for the 3p inverter if that is required?

You should ask your Installer to register the SunSynk inverter and batteries with MCS.

I think his advice not to register was a mistake.

Your 3ph Smart Meter operates under "vector sum" algorithms.
If you're exporting on one phase, and importing on the other two, then you only get charged for the difference between those readings.

Ask if you need this explanation in diagramatic form!

I'm unsure how payments under the Export Guarantee can be correctly calculated unless your Supplier is aware that your claim is made on a 3ph vector-sum basis.

On a related note, did the Installer obtain G99 consent from your DNO when the SunSynk 3ph inverter was installed?

If not you can do this yourself.
Most DNOs have an online form, but I don't know which yours is...

Any SunSynk installation will have no difficulty obtaining G99 approval.
They are the only manufacturer which has a "Zero export to grid" software mechanism that's been accepted by the ENA.

It's important to the DNO that their database of G99 and LCT connected devices is accurate.
That gets used to identify which parts of the Distribution Grid require upgrades and reinforcement.

I can see that data for local substations in the four regions for which NGED holds the Distribution Licence.
I use it a couple of times each week whilst researching issues.

I've truncated the data above and removed location identity information.
National Grid have given consent for limited data to be published for public education purposes.

@transparent I have been brainstorming this Eddi gadget and have a couple of theories. If I have this then during the most productive season I wouldn’t use it for heating the house and only likely use it for the cylinder. When I upgrade the solar panels will it be a worthwhile option, I imagine solar will be greatly reduced but the thermal solar I have assists with the cylinder so perhaps so will the Eddi.  Not much information on it but would I be correct in saying it would perhaps use the immerser although not sure if it would work on reduced current and might feed back the system or a dedicated device/ devices in the pipework.  

The other thing I was mulling over was changing the settings so my cylinder only heats during the period when I’m on the 7p. Currently I have reduced my water temp to 55, but could increase that back up to 60, perhaps setting the legion thing to every night if it supports that.  But the Eddi thing has me interested, I don’t think my inverter does that, but have asked growatt. 

Posted by: @david999

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@transparent I have been brainstorming this Eddi gadget and have a couple of theories. If I have this then during the most productive season I wouldn’t use it for heating the house and only likely use it for the cylinder. When I upgrade the solar panels will it be a worthwhile option, I imagine solar will be greatly reduced but the thermal solar I have assists with the cylinder so perhaps so will the Eddi.  Not much information on it but would I be correct in saying it would perhaps use the immerser although not sure if it would work on reduced current and might feed back the system or a dedicated device/ devices in the pipework.  

The other thing I was mulling over was changing the settings so my cylinder only heats during the period when I’m on the 7p. Currently I have reduced my water temp to 55, but could increase that back up to 60, perhaps setting the legion thing to every night if it supports that.  But the Eddi thing has me interested, I don’t think my inverter does that, but have asked growatt. 

The Eddi is a power diverter, it is used to divert any excess solar generation to any suitable resistive load.

The output from your solar PV system will initially supply any items using power within your home, but during bright sunny days the solar generation can often exceed the home load, with the excess being exported to the grid.

To utilise this excess generation to heat your DHW, a power diverter can be used to only supply the excess to the immersion heater. Using a current transformer the Eddi senses when excess power is being exported to the grid, and then diverts only the excess to the immersion heater, so if the excess is only say 500W, then the Eddi only diverts 500W, not the 3kW that an immersion heater would normally draw if connected direct to the mains supply.

The net effect is that when excess solar power is available, your DHW gets heated slowly, but your system neither exports or imports from the grid.

@transparent invaluable info thank you I'll take this up

@transparent upgrading the lagging as we speak today to find this bodge job. I'm assuming foam filler will help sort this and help with insulation ?

From the photos posted earlier by @bretix  I'm presenting the following overall diagram.

It's derived from the one on p.28 of the SunSynk 10kWh 3ph Installation Manual, but has been chopped & stretched to allow the Sofar inverter to be inserted.

Are you happy that I've presented this correctly?

By looking online, I think those GSL batteries are 200Ah capacity with a 100A charge/discharge capability (each).

So the minimum cable size between each battery and the combiner-block is 16mm² (rated 110A)
and from the combiner to the inverter must be 35mm²

However, the SunSynk installation manual (which an approved installer should follow) states 95mm² battery cable must be used.

The cables in the photo don't look substantial enough to me.

Nor do I like to see them clipped together with cable-ties.
The current rating tables are based on cabling being in 'free air'.

Posted by: @bretix

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upgrading the lagging as we speak today to find this bodge job. I'm assuming foam filler will help sort this and help with insulation ?

I'm not wildly enthusiastic about the use of expanding foam!

The thickness of pipe insulation in your plant room doesn't look adequate in the first place.

If that was my heat-pump pipework, I'd be starting again and following the relevant manufacturers' online guide.
Here's one from NMC, who make the grey Climaflex often sold at DIY stores: