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Opinions on Solis three phase grid ties


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While shopping around I noticed the Solis inverters one of the very very few that appear on COCT's infamous list with NRS-097-2017 certification.

This got me interested in the 15KW three phase model which seems OK on paper and remarkably affordable.

I have a question that appears to be partially answered by going carefully through their installation manual.

I would need to control the power during an islanding situation with the inverter connected to the output of a victron Multiplus - the latter configured to be a simple UPS, excess power from the Solis fed to the grid (if available) through the inverters transfer switch.

During grid fail the transfer switch is open and the Victron inverter does its UPS thing. This allows the Solis grid tie to continue operating. However power needs to be throttled to that required by any loads. The Victron, fitted with the PV assistant, uses frequency shifting to control a grid tie at its output (typically between 51 and 53 Hz with 53 Hz being "off"). Excess power during load dumps is simply shunted into the battery. 

So, anybody used the "Freq Derate" option selectable in the Solis setup ? It appears you can set the min/max frequency for control but the manual is a bit thin in this regard. Anybody have such a grid tie and in familiar with the settings ? Anybody have a contact to somebody knowledgeable perhaps  - not to importers that just move boxes please. 

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13 hours ago, The Bulldog said:

During grid fail the transfer switch is open and the Victron inverter does its UPS thing. This allows the Solis grid tie to continue operating. However power needs to be throttled to that required by any loads. The Victron, fitted with the PV assistant, uses frequency shifting to control a grid tie at its output (typically between 51 and 53 Hz with 53 Hz being "off"). Excess power during load dumps is simply shunted into the battery.  

So, anybody used the "Freq Derate" option selectable in the Solis setup ? It appears you can set the min/max frequency for control but the manual is a bit thin in this regard. Anybody have such a grid tie and in familiar with the settings ? Anybody have a contact to somebody knowledgeable perhaps  - not to importers that just move boxes please. 

I think the first helpful thing to know might be which assistants to use. There are two assistants for doing frequency shift. The first one is the PV-inverter assistant, and this one is normally used in an off-grid situation. The functionality is also included in the ESS assistant, which is the one you will most likely be running in such a setup. In both cases, when you install the assistant on the inverter and you configure the assistant, you can configure the frequency range that the Multi will use. The default is to start limiting at 50.2Hz and by 52.7Hz the power should be reduced to just about nothing. If the Multi needs to switch the PV-Inverter off it will push the frequency to 53Hz.

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You can fill in different values if you use a PV-inverter that works differently. The Multi uses an open control loop for this, it will simply push the frequency as far as it needs to get the power level down.

The reason I am not too fond of a Solis+Victron setup is because the Solis inverter does not support Modbus-TCP. It appears to use Modbus-RTU. They are a member of the sunspec alliance, so I expect they will implement at least a part of it. I do not know if they implement model 123, which is the one you need if you want to use the zero-feedin feature. Presently Zero-feedin is supported only for Fronius and ABB (a very recent development that's still in testing), so the reason I bring this up is merely as a mental exercise as to how much would it would take to support a Solis, to which the answer is: A LOT! Mostly because the ESS control loop (what we call hub4control) has only modbus-tcp support.

So if you can feed all the power into the grid, so that you don't need the limiter, then the Solis is a good idea.

Also keep in mind that using the Solis' own current transformer solution will likely interfere with proper operation in a Victron ESS system. Normally you cannot use both. The same is true for Fronius: Using the Fronius smart meter with a Victron setup is expressly forbidden (as in... you get no support if you do that).

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Thanks Plonkster,

This application would be for grid feed-in so no limiter needed.

No point or advantage using ESS in this application - in fact only downsides (Works really badly with a generator feed even with "B" LOM).

Should zero feed in be needed at any stage it would seem the Solis grid limiter box would do the trick or I could likely hack something together myself.

In this application the only reason to use the PV assistant (and indeed this is what it is for) is when the Mutiplus is islanding, i.e. inverter on and transfer switch open. This allows the grid-tie to continue providing power to loads. To avoid the Mutiplus from releasing expensive smoke power feed from the  GTI needs to be regulated by the Multi by means of frequency shift. This is what the PV assistant does of course - no issue on that side.

It is the Solis I am concerned about - there is a reference in the manual for setting up what they call "Freq. Derate" - this seems to be able to go up to 52 Hz which is still OK. But I don't have more details and am pretty sure none of the importers would know the answer (neither does Google it seems). The Solis inverters seem to be quite widely used in Oz and seem to have reasonable reviews once you sift out the ones where people are complaining about something that seems to be related to setups and not understanding how inverters work.

It's one of the options I am looking at currently. The low price of the Solis is attractive and the fact that the Chinease have already certified them to NRS-097:2017 is quite telling (looks like all the others from MBB, Fronius, SMA etc etc are taking their time). It's pretty much just the new Victrons Solis and Solex that have the new certificates. Almost impossible to get any relevant info or pricing for the Solex inverters so they are out of the running.

Done some simulations this weekend based on the COCT feed in rates and it seems doable in my case if I upsize my solar 10KWp so that is why I am looking at this. It also means I would not have to rewire my house (the new Victron 5KVA inverters only have a 50A transfer switch which is too little for me forcing some rewiring. Nevermind they are three times the cost of the Solis).

 

 

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11 minutes ago, The Bulldog said:

(looks like all the others from MBB, Fronius, SMA etc etc are taking their time)

Been watching that myself lately.

And the list is shorter than a year ago.

My worry is CoCT may be driving the big boys away, over and above the costs of going solar.

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2 hours ago, The Terrible Triplett said:

Been watching that myself lately.

And the list is shorter than a year ago.

My worry is CoCT may be driving the big boys away, over and above the costs of going solar.

Yes to be honest if I were one of them I'd likely give COCT the middle finger. Now a forced re-certification. It's really costly to certify anything - I brush with this myself as that is what I have to do with my stuff - and I cannot do it locally. TUV Rheinland and company are EXPENSIVE. 

But it is not going to help - the new SANS 10142 will force any inverter that is connected grid parallel to have to comply with NRS-097-1.1:2017. So it is not just Cape Town. It is everybody in SA.

I deal a lot with Chinese companies that make various parts for us so it does not surprise me in the least to see the two cheapest of the lot having already certified all their goodies to the new NRS-097. They can and do make really high quality stuff - as long as that is the brief (In other words - they will make any quality you like: you decide).

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10 minutes ago, The Bulldog said:

So it is not just Cape Town. It is everybody in SA.

Jip, I fear for the rest here on the forum who keep on installing everything but certified with "papers" inverters. Not that it any of my business.

I asked Victron a while back to look at Solis, to maybe put it on their list likes Fronius / ABB. But I don't think that is going to happen soon, if ever.

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1 minute ago, The Bulldog said:

if I were one of them I'd likely give COCT the middle finger

It's a combined thing. The grid-tied market is really tiny compared to the off-grid market, so not having certification in one city is really not the end of the world. There is some time left before they have to recertify (and often it is really quick, especially if you already have other certifications that you have to do), and given all the confusion and that we still have draft amendments to SANS floating around... it is by far the most sensible thing to do to wait a bit longer.

4 minutes ago, The Bulldog said:

they will make any quality you like: you decide

Yup. The reason China makes such cheap crap is because people ask them to do it 🙂

2 minutes ago, The Terrible Triplett said:

I asked Victron w while back to look at Solis, to maybe put it on their list likes Fronius / ABB. But I don't think that is going to happen soon, if ever.

It only has Modbus-RTU and we don't know what level of sunspec compliance it has. There is some modbus-rtu code that talks to the Carlo Gavazzi meters that one could port over... but let me let you in on a secret: There is only one reason to do it, just one. Will you sell more Multis by doing this? Frankly I think Solis is going to sell more things to Victron users rather than the other way round.

For ABB it was a bit different. People were already using them together, but they had to use SolarLog to do the grid limiting. Not anymore... 🙂

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5 minutes ago, plonkster said:

Will you sell more Multis by doing this?

No it won't. I concede.

Unless more Victron people follow The Bulldog for I suspect in the last 48 years of Victron existence that there has been quite a few Quattor's / Multiplus's etc sold right here in SA, which could solve their problem with grid tying, as that IS picking up speed in SA, to legally connect their existing equipment.

EDIT: And it is not that expensive to do, to make the Solis work as part of the solution, it is software and maybe a chat to Solis manufacturer.

🙂 

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Just now, The Terrible Triplett said:

Jip, I fear for the rest here on the forum who keep on installing everything but certified with "papers" inverters. Not that it any of my business.

I asked Victron w while back to look at Solis, to maybe put it on their list likes Fronius / ABB. But I don't think that is going to happen soon, if ever.

No I don't think that will happen. But it does not matter. Solis is already supported by Victron by means of frequency shifting.

It's actually simple and elegant. You just need the Multi configured as UPS. No ESS or anything fancy, don't even need a Venus/CCGX. Then you load the PV grid assistant and put anyone of a range of PV inverters on the OUTPUT of the multi and the Multi takes care of controlling the GTI during grid outages. That's great. Some minor rules to obey here but nothing drastic.

But what about zero-feed in you say ?

Well no problem: Looks like all the new Solis single phase grid ties have this built in - just attach a CT at a suitable location. For three phase you have to spend a bit more - they have a dedicated three phase box that uses three CTs to do the job. But it is not a train smash either.

If you want to use a bit of stored battery power during the night rather than keeping the batteries charged, again - no problem, a combination of Victrons assistants suitably configured can create all sorts of conditions where you effectively create your own grid failure which then starts up the inverters. You can base this on load, soc, an external input (perhaps a switch or something more fancy).

I'm starting to like this...

 

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14 minutes ago, The Bulldog said:

I'm starting to like this...

Lekker man!

But I'm one of the guys that are not that interested (anymore) to dig into the nitty gritty. Therein the part where I like to have things pre-programmed, like Solis showing up on Victron's VenusGX, as I don't mind spending the extra for say a VenusGX to make it all simpler.

Plug and Play I say. 🙂 

Am pretty sure there is a rather big bunch of like minded people on this forum and out there.

It could be a cheaper route to go, for say CoCT, to having a Solis on the same level as ABB and Fronius with Victron Equipment for every single Plug and Play Victron user out there.

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3 minutes ago, The Terrible Triplett said:

dig into the nitty gritty

If someone buys a Solis and rigs up the modbus port to their Venus device via an RS485-USB adapter, I'd be willing to poke in its guts to see what is there. That will take only hlf an hour or so, and satisfies my own curiousity as well. I'm not about to go buy one just to try it... daai kan jy vergeet.

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32 minutes ago, plonkster said:

If someone buys a Solis and rigs up the modbus port to their Venus device via an RS485-USB adapter, I'd be willing to poke in its guts to see what is there. That will take only hlf an hour or so, and satisfies my own curiousity as well. I'm not about to go buy one just to try it... daai kan jy vergeet.

OK, I'll sign up to that - can do some logging myself, it's just RS485.

Was thinking of getting the Solis grid limiter anyway (just so I have it in case one day I need it). Then can poke into the protocol and see what it sends out to control the inverters. Should be simple from there...

But first I need to get this whole thing onto a new COCT SSEG application - not buying anything until they tell me they are happy.

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There is an issue though with respect to the Multiplus with grid tie and ESS in the configuration I am looking at.

This is not acceptable to COCT as the "UPS" is no longer defined the way a UPS is to work. Grid parallel is allowed but ONLY if the inverter is then also NRS-097 certified.

If it is not as in the case of the older Muties and Quatros then it must work as a UPS exactly as per definition in the SANS document. The Multies are fine with that but only if not run grid parallel.

 

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3 minutes ago, The Bulldog said:

Was thinking of getting the Solis grid limiter anyway (just so I have it in case one day I need it). Then can poke into the protocol and see what it sends out to control the inverters. Should be simple from there...

It's a current transformer, so it is essentially an analog AC signal. Really not much to it as I understand it.

What you can do as a start, is query the first two register at 40000 on whatever slave id it uses. What we're hoping for is 0x53 0x75 0x6E 0x53. Because modbus uses 16-bit values, this fits into two registers, and put together it literally spells "SunS" in ascii. If you see that, then we're in business. What follows after that (from 40002 onwards) is two registers, the first one indicates the sunspec model, the second one the length. You can use the length register to skip to the next one, and so you can find all the models. Usually you will see model 1 (this is mandatory and must be first), then 101 (single phase inverter) or 103 (three phase inverter), 120 (nameplate info), and 123 (immediate controls). It can work without 123 (then you only get information, no control), but the ideal would be to get model 123 as well.

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8 minutes ago, plonkster said:

It's a current transformer, so it is essentially an analog AC signal. Really not much to it as I understand it.

What you can do as a start, is query the first two register at 40000 on whatever slave id it uses. What we're hoping for is 0x53 0x75 0x6E 0x53. Because modbus uses 16-bit values, this fits into two registers, and put together it literally spells "SunS" in ascii. If you see that, then we're in business. What follows after that (from 40002 onwards) is two registers, the first one indicates the sunspec model, the second one the length. You can use the length register to skip to the next one, and so you can find all the models. Usually you will see model 1 (this is mandatory and must be first), then 101 (single phase inverter) or 103 (three phase inverter), 120 (nameplate info), and 123 (immediate controls). It can work without 123 (then you only get information, no control), but the ideal would be to get model 123 as well.

No, the three phase box has a microprocessor in it and a whole setup thing - you can control exactly how you want to limit currents in the system as there are several ways to do it depending on your preferences and load profiles. The CTs connect to the box and that communicates to the inverters via RS485. I have no idea on what the protocol is and Google throws up nothing. I suspect it may be quite simple - I'll put a bus analyzer on it when I have this going. It is apparent that it can control individual phases so this is interesting.

The single phase solis inverters just have an analog input for a CT and contain the limiter as standard. Not sure if these can be controlled via RS485 but I suspect that they can.

 

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  • 10 months later...

i realise this is an old topic, and I'm a newbie.... 

@The Bulldog , hope you can help since your installation sounds similar.

If i buy a 30kw solis 3 phase, and install a victron quattro on 1 phase, + most of my house load is on that same phase, will the solis 3 phase basically allow most of the solar generation load to be used by the one phase?  I'm struggling to find documentation that is clear about the solis capability, but I assume for now like other 3 phase solar inverters, each phase can only be a 3rd of the total.

I'm planning to install 36 x 405w canadian solar panels for circa 14.5 kw generation capacity, all connected to the solis.  

All the load is on a single phase with just a 3 phase heatpump for underfloor heating in winter.

 

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  • 6 months later...

Can any of you guys please indulge me as I am considering a Solis grid tie  5 k Va  to add to my existing system. Does the Solis work with a Mercer 5 kva  operating as the UPS. I am in Johannesburg and would like to limit export to Eskom to zero is this possible. 

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1 hour ago, @Mak said:

Can any of you guys please indulge me as I am considering a Solis grid tie  5 k Va  to add to my existing system. Does the Solis work with a Mercer 5 kva  operating as the UPS. I am in Johannesburg and would like to limit export to Eskom to zero is this possible. 

I am no Pro when it comes to this technology however I have done a lot of research on Frequency shift inverters and so far there are only a few inverters on the market that can do that namely Victron SMA Sunny Island MLT Drivers Oasis Outback Schneider and a few others they call it AC Coupling some systems use AC or DC Dump loads to dissipate excess power generated by the grid tied PV also the Grid tied PV inverters that support this are SMA Solis Fronius and a few other brands, With that Said I am Sure @plonkster and @The Bulldog probably confirm my suspicion that Axpert clones do not support this technology.

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  • 2 weeks later...

Frequency shifting to control the Solis inverters works great - been doing that for quite a while now.

Yes, you need an inverter that is able to do so AND you need to be able to control that frequency shifting process (setting the frequency limits) so you can balance the operation to perfection. You cannot change the limits in the solis (at least I don't know how) but if you look at the NRS test results which they publish you can see nicely how it works. So you need to be able to configure the other side to prevent this to become just a glorified on/off switch with sort of a ramp in the middle.

There is more to this - your inverters must be able to use your batteries as load dump as regulation is not instant - this means your battery charging, battery capacity and inverter instantaneous power generation comes into it. This means your inverter cannot be a simple one - it needs a bit of brains to be able to control and handle this.

If all of this is in place it does work well though and is a simple solution.

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  • 1 year later...

@The Bulldog Just wanted to get an update on how this is going for you ?

 

I am in Australia and have a 25Kw 3 phase Solis inverter - our electricity provider exposes us to wholesale prices so very often during the day the prices go negative and we wish to either stop or limit the amount we feed to the grid.

I wonder if you ever got around to debugging the output from the Solis EPM to the Soliv Inverter - my inverter has a RS485 port for the EPM to plug into but as i already have a whole of house monitoring system that runs through Node Red i would prefer to not buy the seperate box but rather set the appropriate modbus registers 

I have the Solis Modbus Documentation that i have found on the internet but it does not seem to specify which registers could be used to limit output production capacity

 

Craig

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