Rosh - Quantum Solar

An expanded, consolidated version of this review can be found here: https://technica.thalmanns.com/2024/12/solis-s6-pro-hybrid-single-phase.html
I recently decided to give the new Solis S6 inverter (S6-EH1P6K-L-PRO) a long test drive by replacing the 4-year-old Goodwe 5048ES at my home with the Solis. The purpose of this was to evaluate the performance of the inverter in a real-use environment over an extended period, and largely compare it to its closest Sunsynk equivalent, which is a favourite local hybrid option. I should note that the 5kw and 8kw versions of this inverter are physically very similar and most of what is indicated here will apply to those models as well.
Since the inverter is located in a noise-sensitive location, I opted for the largest fan-free version, which is the 6 kW model, and this sports a large passive-cooled heatsink on the back of the inverter, as per Sunsynk and Goodwe. The 8 kW model uses fans for forced-air cooling and until I’ve heard the noise profile of the fans, which can often be more miss than hit with inverters, the 6 kW version sounded like the best fit. I had initially planned on using a single 5kW Sunsynk and then possibly expanding to two in parallel over time but decided that given the apparent attractiveness of the offer, the Solis warranted some investigation.
Specification-wise, the Solis looks compelling, with a price tag of the 6 kW version essentially matching the ubiquitous and benchmark 5 kW Sunsynk, with both inverters being NRS certified for South Africa and offered with a 5 year warranty. It does have some notable features, besides the obvious power output advantage, that make it stand out though. It has wide voltage range MPPTs that startup and operate from 90V making an array starting with three panels possible. It’s upper MPPT (520V), maximum operating voltage (600V), and peak operating current (16A) are also higher than the Sunsynk. This all ends up with the total maximum PV input power on the Solis being 9.6 kW compared to the Sunsynk’s 7kw. Overall, this suited my existing solar array setup better, and ultimately makes the Solis notably more flexible on this front.
Connection-wise, the inverter feels rather like a Sunsynk as well. In addition to the Grid and Load ports, a Generator/Auxiliary port is also present, although it currently appears this port is only configurable for power input, not output as well as with the Sunsynk. There is an external CT clamp connection for the internal power meter, although the supplied CT cable length is a bit miserly at around 1m or so. The usual battery BMS, parallel and RS485 (MODBUS) ports are also present, as well as a generator start signal and grid-loss relay outputs. However, the inverter automatically bonds Neutral and Earth at the Load port on grid loss, possibly controlled by the Grid Standard setting selected, so an external contactor, if required for grid code conformance, would not be required for this inverter, as was the case with my previous Goodwe.
Installation was rather straight forward with no unwelcome surprises or irritations. The inverter hangs on and is secured to a simple separate wall mount bracket that is easy to install. I did note that the inverter heatsink and internal PE terminals are not electrically connected and must be bonded as specified in the user manual. Once all the connections were complete, the inverter’s relatively simple but elegant-looking display lights up, giving a basic battery SoC level-type indication, any alarm state, and the active state of the WiFi and/or Bluetooth interfaces. The inverter has a chunky WiFi dongle as well as a Bluetooth antenna that protrude from the bottom of the inverter, but that shouldn’t present a problem unless (incorrectly) installed in a space-constrained environment. So far so good.
Solis decided to forgo a display and buttons on the inverter itself and rather leverage long-range Bluetooth and WiFi for commissioning the inverter via the SolisCloud App. After downloading the App, and creating an account, connecting to the inverter was relatively straight forward and fuss-free. There are a significant number of configuration sections and options to potentially fiddle with, but thankfully Soils has created a quick start shortcut that takes you through the few steps of setting up the basics, such as the type of battery, to get everything running. My inverter is paired with Pylontech batteries and the BMS comms worked flawlessly out the box. I was impressed how quickly and easily I managed to get everything working. After some initial fiddling, I did realise I had installed the CT sensor the wrong way around (arrow towards the grid, as with Goodwe, but opposite of Sunsynk). However, there is a configuration setting in the inverter that allows the direction to be corrected in software, which I promptly enabled to avoid any more physical labour, but found the inverter was still doing unexpected things, like exporting battery power to the grid when I had told it not to export anything. In the end, I begrudgingly took out a screwdriver and opened the DB board again, corrected the CT direction and then everything worked as expected. So nice idea on the CT setting, but maybe it needs a bit more work in terms of all the effects on the inverter’s various modes of operation.
Which brings me directly to my first notable issue I have with this inverter. As per the Goodwe, it’s missing a Sunsynk-like time-of-day multi-minimum SoC setting operational mode. It has quite a few operational modes, but those that do, only allow the definition of charge and discharge times and power, just like the Goodwe. Maybe this makes sense when using Time of Use tariffs, but otherwise just seems unnecessarily befuddling and complex for the average South African that just wants to make the sure power stays on. You can however set one reserve SoC per mode, which will tell the inverter when to stop discharging the battery, but this is not as flexible and useful as the Sunsynk SoC timer where setting different SoC values depending on the time of day is possible.
Also, as seems standard in the inverter industry, there are a multitude of settings that have no reference in the manual, probably due to newer firmware releases since the manual was published, but descriptions for many settings are simply not defined anywhere – videos, the Solis website or otherwise. Making setting available without proper documentation for installers or end-users is just poor practice, but again, even Sunsynk is guilty of this habit.
Thus far, after about two weeks, the inverter has worked flawlessly, without issue. In my home, I typically run all essential and non-essential loads off the inverter, so this includes running a 3kW geyser, electric stove and two inverter-type air conditioners. Of course, not everything runs at the same time and some load management is still required, but the extra 1.5 kw headroom over the 4.6 kW Goodwe is certainly appreciated. I have also noticed the inverter seems to run noticeably cooler than a Sunsynk 5 kW, as well my previous Goodwe, with the heatsink only getting noticeably warm after running the geyser for its daily Geyserwise-controlled cycle. The inverter does appear to have an internal fan, like a Sunsynk but quieter, and I’ve only heard it turn on once when my CT-issues caused it to export 6 kW to the grid. Plotting the internal inverter temperature on the SolisCloud app shows the inverter internal temperature has not gone above 48 C yet, with the inverter being mounted in a ventilated cupboard.
Which is a good time for me to raise my second notable issue with the Solis S6. Say what you want, but there is something innately appealing about the simplicity of a touchscreen and buttons, where you can always go press a button, change a setting, and see (or not) the results immediately. The problem with the Solis is that without a physical interface, the user is highly reliant on their technical ability to use the App, the useability of the App itself, and reliability of the ability to connect to the inverter. This was the main problem with my previous Goodwe, where between the flaky WiFi interface and glitchy infrequently updated software, interacting with the inverter became a largely “touch-once, and forget” affair. Monitoring the inverter via the WiFi app mostly worked, but most irritatingly sometimes didn’t. And have mercy if you needed to change configuration modes or something similarly esoteric like that – often you simply weren’t sure if the change had been applied or if a good old inverter reboot was required first.
Unfortunately, while significantly better than the Goodwe software, the SolisCloud App currently has a lot of rough edges and issues. This is understandable to an extent with a relatively new Solis cloud platform and range of inverters but needs to be considered when comparing to a well-established and more mature platform offered by Sunsynk. However, some of the issues leaves one wondering what they are thinking exactly and how some of these issues are making their way into released software. For example, on the cloud platform the data displayed in the basic “real-time” power flow diagrams is incorrect - PV power values being shown at night for example. Also, the App and inverter supposedly have two methods of connecting to and configuring the inverter locally – via Bluetooth and WiFi. The Bluetooth method is the only method described in the manual and videos that I could find on the web. The WiFi method is there but doesn’t appear to work, throwing connection/password errors that don’t appear to make sense. And then a recent automatic App update seems to have bricked my ability to connect to the Inverter at all via Bluetooth – all I get is a blank screen and nothing happens whereas before it worked without issue. Restarting the inverter and phone hasn’t helped. So now, I have no way of configuring the inverter locally – which isn’t particularly confidence inspiring.
This brings me on the third and final issue with this inverter, which relates to remote configuration. If you are an installer, you can’t currently manage customer inverter settings remotely, which is a big downside when compared to the Sunsynk platform. As an end user, it is possible to manually request this remote management functionality. I have done so and am able to configure the inverter this way, at least until Solis can sort out the local configuration issues. It would be interesting to understand the reasoning why this functionality cannot be enabled by default or at least be controlled via a local setting for security reasons. The Solis web site does seem to allude to the fact that the remote management of inverters by installers may be possible at some point in the future. However, until that time arrives, if ever, it means my choice of supplying a customer a Sunsynk or a Solis will always favour the former as remote access is such a critical and time saving feature.
As this is a long-term test and evaluation of this inverter, I will continue to experiment and note changes/updates made to the inverter’s operation. There are certain aspects that I have not tested yet, such as the behaviour and power control in feed back to non-essential loads, which will develop over time.
So in summary, the Solis S6 inverter has serious potential to offer a competitive alternative to the current local favourite Sunsynk’s benchmark offering, but is hampered by firmware and software issues, all of which needs to be addressed promptly by Solis. As with any technical device these days, great hardware can be ruined or rendered forgotten by poor software.
Pros:
6 kW power for the same price as a 5 kW Sunsynk. More flexible PV capabilities compared to a Sunsynk. Runs relatively cool and is practically silent. Cons:
Inverter has no SoC-level timer operational mode. SolisCloud App needs work to make it reliable. Remote configuration for installers is missing.  
*** Update - 21/07/2023 ***
I was contacted by the Solis' local technical support team to try sort out some of the issues I had encountered - thank you for the proactive support!
A remote firmware upgrade of the inverter was performed, and it was suggested I try uninstall/reinstall the SolisCloud app as well. The result is one of these actions solved the local Bluetooth connection issue, but I can't say which, so if anyone has the same issue, I would recommend try either clearing the app cache (in the App, go to Me->Settings->General->Clean Cache) or uninstall-reinstall the app first. For reference, you can contact the local support team at [email protected] to request a firmware update - you will need to send them the inverter S/N and data logger S/N.
Also, contrary to what is specified on the Solis website, local Solis support informed me it is possible to remotely configure inverters from a single "installer" type account that contains multiple customer inverters and we are in the process of activating it on the account and I will test drive the functionality once available. Again, please contact the local support team and they will assist in organising the functionality for those that require this.
Finally, the local support team did indicate they would put in a request for a SoC-schedule type operating mode, so I'm holding thumbs. For some users, they may be fine with one of the current operating modes with a single minimum SoC threshold, but a schedule would just be better and simpler for South African conditions.
*** Update 30/07/2023 ***
Solis enabled my installer remote control access and I can confirm I can now control my inverter through my installer account as well. Apparently remote access will soon be enabled by default for end users.
Travis, Product Manager from Solis, also confirmed the SoC schedule is in the queue to be implemented which is great news
After my recent firmware update, I see the inverter now also has options for using the Aux port as an output port, as per Sunsynk, but it seems the CT software reversal setting has disappeared, possibly related to operational issues as noted in the review.
Some bugs in the apps and Bluetooth interface have been addressed as well, and thankfully, the last password used to log in via Bluetooth is now automatically remembered. The local WiFi config mode still doesn't appear to work though.
*** Update 30/10/2023 ***
Some developments:
- The inverter has some strange battery charging behaviour, at least with my Pylontech batteries. It will charge the batteries to 100% SoC but then seems to stop, even although the battery BMS charge current limit has not reached 0, which I believe is incorrect. Oddly, this behaviour only occurs when the grid is not connected. As soon as the grid connection is enabled, the inverter ramps up the solar to charge the battery until the battery sets the charge current limit to 0. To me, this indicates a bug in the inverter firmware but the local Solis support doesn't seem to agree. The firmware of all the batteries (mixture of US3000/US3000C's) is up to date. I should also note that the 8kw Solis inverter I've replaced the 6kw with now doesn't do this but does instead charge to 100% SoC until the charge current is zero (without grid) but then seems to let the SoC decay, even after the battery BMS lifts the charge current limit from 0, indicating it wants charge. Not sure yet at what SoC point the inverter would decide to charge the battery again.
- I upgraded to the 8kw model for comparison. The two inverters are physically very similar except the 8kw has two more MC4 connectors for paralleling one of the PV inputs and has 3 fans mounted at the bottom side of the heatsink for active cooling (air is blown upwards). The mounting bracket for both is almost the same but not identical (the holes for the screws for securing the inverter are not quite in the same location) so I had to swap the mounting bracket but everything else was easy to reconnect. Pity Solis couldn't make the bracket the same for all the models - this could be useful for installers to do easy upgrades or temporary unit swaps.
The fans on the 8kw don't run under most conditions. They are either on or off, and when running are fairly loud (with a noise signature akin to a jet engine 😁) so I wouldn't mount the inverter in a noise sensitive location. The fans always turn on when the inverter power (load or solar power into batteries) is greater than 3kw, or when the internal temperature rises above around 46C or so. Generally this doesn't happen often or too frequently and isn't too problematic, but if you have a cloudy day where the solar is ramping up/down, the fans can turn on and off constantly as the sunshine ebbs and flows which isn't very intelligent. I think the fan behaviour could be better designed, especially the part where the fans always turn on above a 3kW load. I would like to understand why it isn't possible to make this component/heatsink or ambient temperature instead, unless it points to a design compromise, maybe something similar to what is generally done with Voltronic inverters where the lack of passive cooling needs to be made up with active cooling. At least the fan speed doesn't ramp up or down based on load, which must be the most audibly annoying feature possible.
I will note again that the 6kw inverter (and probably the 5kw version as well) run much cooler than the 5kw Sunsynk. Even the 8kw seems to be much the same as the 6kw in this regard, with the inverter heatsink never getting to the egg-frying touch temperatures experienced with the Sunsynks.
- The app configuration settings are a bit of a mess at present, seemingly more so now than in the past - hopefully this will be addressed soon! Many settings that used to be available when I first installed the inverter have been removed or may have been hidden which is a bit frustrating. This also results in situations where the local Solis support directs a user to change settings that simply don't exist. Case in point is they had to remotely do a factory reset of the 6kw inverter as the supposed option to do so simply does not exist in my app, which is the latest version.
- Note that there is still no SoC-timer work mode functionality present for these inverters.
So which to choose between the Solis and Sunsynk right now? Inverter prices, along with all other components have been dropping nicely over the last few months and the 5kw Sunsynk is now typically a bit cheaper than the 6kw Solis. Admittedly the improvements in the software and firmware on the Solis side are not where I'd hoped they would be by now. Hardware wise, the Solis still appears to be a close and in a few cases, a better match for the Sunsynk. However, the software (firmware and app) side continues to be the main problem area. If you want a mature platform that is less likely to give you some grey hairs and that is arguably easier and simpler to use right now go with the Sunsynk. 
 

I've set my inverter with the following voltages:
Float: 53.6 V
Absorption: 53.8 V
Equalization charge: 53.8 V

This seems to have stabilised that erratic discharge and charge process. Thanks @Rosh for the suggestions. Really appreciate it

I agree - I almost bought these - That Model Number doesn't exist in the Narada range 45NFPC200 

I am really new at this solar stuff and having installed a Sunsynk 5.5kw inverter about a month ago I thought it would be a good idea to add some solar panels. Being a bit of a handyman, and always looking for new projects around my house, I thought this would be a breeze. 
Needless to say, it was not as easy as I thought and being a absolute newbie, the biggest problem I faced was where to find sound advice and information.
From the actual installation of the roof hooks and rails to what I would have thought was simple stuff like the distance between rook hooks (along the length of the rail) and and how far apart (top to bottom) the rails should be etc. was a nightmare trying to find the correct imformation. I visited so many stores and tried to search Youtube as well as this forum. Someone also told me that I must I also cut the roof tiles and I remember telling myself - what on earth is this bloke talking about.
Anyway, with the little bit of information that I could find, I went about installing the roof hooks and rails and thought I would share what I did - perhaps someone else may find it useful (or possibly others may be able to tell me if I did something wrong).
I was advised that the roof hooks have to be between 1m and 1.5m between each hook. Considering your roof rafters are about 750mm-800mm apart, I suppose the 1.5m width seams accurate with a hook on every 2nd rafter. Someone did tell me you need a hook on every rafter (every 800mm), but the cost of doing it this way would be huge if you consider a roof hook costs between R150-R200 per hook. (A 6m lenth rail would then require 7-8 hooks totaling between R1050 and R1600 just for the roof Hooks - then add a 6m rail and the total could easily be around R2K to fit each rail which just seams over the top. So I went with 5 hooks over a 5.5m length with a gap between 1m and 1.5m. I also added in an extra hook on 2 of the rails just because it made me feel better 🙂 . Below is the final installation of the rails.
I hope someone will find this info useful or perhaps if I did something wrong someone could tell me before I fit the actual panels.