Upscaling the solar generation on our property 2

[Countrypaul]

Surely you could just allow the multiplus to export the surplus electricity if you cannot use it yourself.

From several previous threads, I supect your supplier doesn't realy understand the configuration of the complete FIT system including TGM being a simple input into the multiplus.

[openspaceman]

Surely you could just allow the multiplus to export the surplus electricity if you cannot use it yourself.

Yes when on grid but I wonder how it would cope with an off grid situation.

My difficulty is while I have a basic understanding of electricity I have no background in working with it. So my original system was specified and fitted by an installer as was the later addition of the battery by a different firm ten years on. The year old battery charging array was do it myself with a bit of hand holding from here. The next proposed addition must be done by a qualified electrician but he is not a solar PV person so I have obtained DNO permission based on using the multiplus.

I cannot afford to start again from the beginning and do not want to lose my FIT. I am doing stuff incrementally by using my FIT money.

[nowty]

Surely you could just allow the multiplus to export the surplus electricity if you cannot use it yourself.

Yes when on grid but I wonder how it would cope with an off grid situation.

My difficulty is while I have a basic understanding of electricity I have no background in working with it. So my original system was specified and fitted by an installer as was the later addition of the battery by a different firm ten years on. The year old battery charging array was do it myself with a bit of hand holding from here. The next proposed addition must be done by a qualified electrician but he is not a solar PV person so I have obtained DNO permission based on using the multiplus.

I cannot afford to start again from the beginning and do not want to lose my FIT. I am doing stuff incrementally by using my FIT money.

Worst case your solar inverters will simply trip out through overvoltage or frequency shift. My SMA system gets round this by controlling the solar inverters and throttles generation to keep AC voltage stable in Off Grid mode.

What your suggesting will not make your FIT system non compliant, your supplier might be thinking an Off Grid system becomes non compliant but Off Grid systems have always been compliant with FITs.

[openspaceman]

Worst case your solar inverters will simply trip out through overvoltage or frequency shift. My SMA system gets round this by controlling the solar inverters and throttles generation to keep AC voltage stable in Off Grid mode.

What your suggesting will not make your FIT system non compliant, your supplier might be thinking an Off Grid system becomes non compliant but Off Grid systems have always been compliant with FITs.

I have had a reply from my supplier it differs from what their first man said, rather it adds vital detail that amplifies what Nowty posted; i.e. the Multiplus 2 can only have off grid inverters installed on the AC output so long as the inverter has frequency shift/response enabled.

Which my solarmax probably doesn't so a bit of rethinking required.

[Kommando]

My SMA Sunny Island throttles my SMA inverters on my off grid system by changing the frequency, however I have a PI running Node-Red that monitors this frequency and when it starts climbing turns on WiFi connected plugs with loads. This effectively means the inverters never get throttled as long as the loads are sized correctly. Even your Solarmax will have a frequency over which it will disconnect from the 'grid', a cruder form with no gradual reduction. This will be 52htz but should be adjustable in the settings as long as you have installer access.

[openspaceman]

As I said I am having a re think.

I have tried running the whole house by connecting a 5kW inverter and battery to the generator socket of the changeover switch. It works and the Solarmax and growatt inverters stayed live such that there was no apparent major draw on the battery i.e. the wave form was good enough, where my generator's was not, to make the other inverters think they were grid connected and working.

That is until the Solarmax started ramping up the voltage I think, as the the 5kW inverter sensed a voltage problem and shut down so the whole system shut down too. I need to try it again in the dark when I have charge in the growatt battery.

I'm thinking I will move the new panels and charger (and future ones) to a Multiplus with pylontech batteries to a new consumer unit just for essential loads then in the future if I pursue the off grid thing just change the solarmax.

The thing is with the better export tariffs now their income will exceed the standing charge which was the thing that annoyed me. I am still waiting for my export MPAN to be organised by Octopus.

[Andy]

Surely you could just allow the multiplus to export the surplus electricity if you cannot use it yourself.

Yes when on grid but I wonder how it would cope with an off grid situation.

My difficulty is while I have a basic understanding of electricity I have no background in working with it. So my original system was specified and fitted by an installer as was the later addition of the battery by a different firm ten years on. The year old battery charging array was do it myself with a bit of hand holding from here. The next proposed addition must be done by a qualified electrician but he is not a solar PV person so I have obtained DNO permission based on using the multiplus.

I cannot afford to start again from the beginning and do not want to lose my FIT. I am doing stuff incrementally by using my FIT money.

I have my Solaredge on the dropped output of a Quattro AC OUT 2. I have a relay so I can manually put it back on the AC OUT 1 if I am happy that the battery won't be fully charged when I don't notice ie in the winter.

If you have existing inverter on the AC OUT 1 then you can cause damage to equipment in some circumstances. If the batteries are full and the you have a grid failure then the AC voltage will start to rise very quickly. There is a victron document about this that is worth reading. https://www.victronenergy.com/live/ac_coupling:start.

Here is my layout. I have a three pole switch after the quattro so I can bypass it for maintenance. The whole house can be put back on the grid. Switching the second change over so the Solar Edge/car charger/heatpump can be fed from the plant distribution board. This is driven by AC out 1 or grid.

It might be different to your set up as I have an 8kW inverter so run it in series. You can run the victron kit in series or parallel. If you are running in series then make sure that the current the relay support in the Multiplus you have chosen will support your maximum load. I think it's 100A with the 5kw version but worth checking.



Another diagram showing the same layout

[Andy]

It is nearly a year since I have had my 1785W battery charging array running, it has produced an extra 962kW and enabled me to go 236 days between 3rd March and 3rd November without buying electricity other than the daily ~1/3kWh import that seems to be a result of the poor integration of the mishmash of components. We are currently buying about half our electricity needs.

After discussion here I was on the point of ordering a 5kW Victron Multiplus to sit between the grid and my current 4kW Fit system with the intention of adding 10-13kWh of Pylontech batteries and 1600W of PV. The idea being the multiplus would keep the FIT system generating in the event of a power cut and if I get around to running islanded with a DC generator. I would have to live with a 5kW maximum load.

My worry is would the multiplus cope with being pushed by 4kW of excess power from the PV once the battery is full and with no draw from the house?

Further my supplier is now suggesting it would make the FIT system non compliant and this should only run in parallel with the multiplus, which means the fit system would not generate when off grid.

Any thoughts?

If you go down the multiplus route, I really love my setup. If you are running a cerbo gx or similar to control the Multiplus, it is like having a super power. The node red control allows amazing things to be done. My next project will be integrating the octopus car charging to charge the battery at the same time when my smart meter starts working.

--- WARNING!!! ----Just a heads up on updating firmware during the initial install. Don't do what I did. I had it connected to the AC only and commenced the update. The first one worked more by luck than anything. It disconnects the AC and then it completed the update on the stored charge in the capacitors. I didn't realise this and the second update completely borked everything and I ended up with Quattro sat there flashing all its lights at me. There was no communication with the cerbo. I had no power for my old laptop that had no battery life and needed to download a new boot image from the professional site. Then I had to do some funky stuff to get the images uploaded to the quattro. I didn't have a change over switch at that point so had to disconnect all the AC wires and reconfigure to get the house working. None of the wires were the right length at this point. This was approaching darkness and in the middle of the winter :< Do yourself and favour and always have DC connected with a good bit of charge. There is nothing I have seen in the documentation stating that the DC is the primary power for the control unit and everything you do is predicated on that being connected!

[Kommando]

Reading the manual for the Solarmax 4200S it does have the ability to be output limited by frequency. You need to set it to Germany instead of UK, then you can set the start frequency, ramp slope and 0% frequency. However there is also a setting for limiting output based on voltage which is not country dependant. Get the Maxtalk software to make the adjustments.

[openspaceman]

Thanks, that's good to know. I'll dig the paperwork out, I have left well enough alone for 12 years for fear of fouling the FIT system up but tif I can get it working that would solve the problem with the multiplus.