GreenFields

Hello Hennie
The Pro Models are the first line of S6 Hybrid inverters they do not have display screens on the inverter and use Bluetooth, Lan and WIFI via the Solis Cloud app for config and setup these are the 3.6, 5, 6 and 8 KW LV Models. All HV models have display screens. They also have the very wide range MPPT units that start producing at 90VDC and has a maximum voltage of 600VDC.
As an example the 6 KW Unit for the pro model can produce 9.6 KW PV on its two MPPT's
They all have an IP66 Rating and has all the feature sets like AFCI 200% Load for 10 Seconds 4ms changeover AC Coupling Generator integration on AUX port or grid with signal and auto start and they truly blend power like Victron and a lot more.
They all come with a standard 10 year warranty.
The newer Solis Plus Models have large display screens on the front of the inverters for the 5, 6, and 8 KW Solis introduced the screens due to user demand they still have Bluetooth Lan and WIFI.
They also have all the feature sets like the older model with some extras like the large display their MPPT's wake up at 89VDC and produce at 90VDC but is limited to 500VDC however their PV capacity is 200% of the inverter rating so the 6 KW Unit can produce 12KW from its two MPPT's
These models all come standard with a 10 year Warranty 5, 6 and 8 KW units however the larger LV models 12 14 16 KW units have a standard 5 Year warranty with a warranty extension option up to 25 years (to be confirmed) the 10 year extension is available some distributors sell these models with the extended 10 year warranty included but there will be a marked price difference so be aware of that when buying the larger models this also applies to the HV Models standard 5 Year warranty with some Distributors selling 10 year warranty models.
We try to sell mainly 10 year warranty models we constantly have to check the prices to ensure the model we are selling is 10 Year if not we will let the buyer decide if he wants a 5 Year or 10 Year warranty machine.
Important point on the Solis Warranty is that its a Swap out warranty and NOT a repair warranty. Their turnaround time is fast and efficient with no unnecessary delays.
As a Comparison Currently have a client with a Sunsynk inverter where the inverter was sent back for warranty repair its now 1 month and 2 weeks and we still have no feedback on if the inverter will be repaired under warranty or not needless to say the client is freaking out.
All of the Solis inverters are NRS097 Approved and Solis Brand is a Tier 1 Inverter brand Sunsynk / Deye for example are Tier 2 Inverter brands.
We just recently sold a system to a client that included 2 x 6 KW solis pro Inverters 24 x 460 Watt JA Solar Bi Facial panels with roof mountings and 2 x 15.3 KW Active BMS batteries and all the cable and required accessories for around R113 000 EX Vat and that included delivery to his doorstep. In my opinion that is a very robust system at a very reasonable price.

If you are keen on fitting panels to the South-West roof, even if it's sub-optimal, bear in mind that the 12kW inverter has got three MPPT's, which can also take parallel strings. You could therefore combine your orange and red strings onto the first MPPT, two six-strings in parallel, leaving an MPPT free for the South-West side. Maybe you might struggle to fit at least 4 of the 600W panels, but if you could say fit 4, but better 5 of the 450W panels to MPPT3 facing SW, that could plausibly work.

Please don't delete the question, you never know if maybe someone else comes looking for the same answers in the future.
I want to say, though, that not everyone necessarily has the same experience. I've had my flat plate split system now for nigh on 10 years, and my pump has never given in. The panel itself has had a 10-year warranty, so maybe I should start expecting hassles soon, but so far it's been plain sailing. The only gripe is that it is not as effective in Winter as in summer, but it still helps by reducing the amount of top-up heating needed.

The usual disclaimer: Layman's opinion, personal 2c worth, use at own risk, to be adapted for your own situation, get professional advice.
On the first comment, that you are early risers, etc. I agree that people have their own routines, own usage patterns, and that the optimum solution in one case might not work or make sense for others. The idea of increasing the water temperature to 70 degrees might work for people who want to store as much heat energy as possible for evening baths & showers for the kids, but if you then have adults who want to freshen up with a morning shower, I'm not sure if that using the geyser as a battery is always a workable strategy. For those who need hot water first thing in the morning, there's this idea to run off battery, alternatively a heat pump could do that heating for the morning (and generally) more efficiently off battery and solar. Finally, what I'm doing, is running the geyser from the grid in the early morning, using a timer, while on an off-peak time-of-use tariff that's cheaper.
Back to the battery, though, I'm wondering if the concern about "using up the battery" on low-grade non-essential tasks like water heating really... yes I'm going to say it ... holds water. Firstly, if you need hot water in the morning for the family to wash and go to work, school, etc. then that to me is essential and time-critical. Beyond a point you can't shift all loads to the day.
Next, though, I'm wondering whether the cost of the battery is really such a big factor as it was before, from the point of view that the cost per kWh cycled in and out of the battery has come down dramatically. Just using this 15kWh battery as an example (and I'm sorry for harping on it, I'm not a spokesperson for it, I just like the concept on paper), then 80% cycling down times 6000 cycles gives a cost of around R0.40 per kWh. A third of what it used to be when I first bought. You can't run from the grid at that price. Okay, one should factor in the capacity loss and installation costs and go on full quotations, but say that it ups the cost to R0.80/kWh. You still can't buy power from Eskom at that price, so I'd say to let rip, run a 2kW or even a 3kW element, well within the 100A recommended discharge capacity of the battery, without a second thought, and start treating home battery power like a disposable. The fact that some of these big batteries are floor-mounted and come with trolley wheels, tells me it shouldn't be that hard to swap them out while running on grid in the interim.

The usual disclaimer: Layman's opinion, personal 2c worth, use at own risk, to be adapted for your own situation, get professional advice.
On the first comment, that you are early risers, etc. I agree that people have their own routines, own usage patterns, and that the optimum solution in one case might not work or make sense for others. The idea of increasing the water temperature to 70 degrees might work for people who want to store as much heat energy as possible for evening baths & showers for the kids, but if you then have adults who want to freshen up with a morning shower, I'm not sure if that using the geyser as a battery is always a workable strategy. For those who need hot water first thing in the morning, there's this idea to run off battery, alternatively a heat pump could do that heating for the morning (and generally) more efficiently off battery and solar. Finally, what I'm doing, is running the geyser from the grid in the early morning, using a timer, while on an off-peak time-of-use tariff that's cheaper.
Back to the battery, though, I'm wondering if the concern about "using up the battery" on low-grade non-essential tasks like water heating really... yes I'm going to say it ... holds water. Firstly, if you need hot water in the morning for the family to wash and go to work, school, etc. then that to me is essential and time-critical. Beyond a point you can't shift all loads to the day.
Next, though, I'm wondering whether the cost of the battery is really such a big factor as it was before, from the point of view that the cost per kWh cycled in and out of the battery has come down dramatically. Just using this 15kWh battery as an example (and I'm sorry for harping on it, I'm not a spokesperson for it, I just like the concept on paper), then 80% cycling down times 6000 cycles gives a cost of around R0.40 per kWh. A third of what it used to be when I first bought. You can't run from the grid at that price. Okay, one should factor in the capacity loss and installation costs and go on full quotations, but say that it ups the cost to R0.80/kWh. You still can't buy power from Eskom at that price, so I'd say to let rip, run a 2kW or even a 3kW element, well within the 100A recommended discharge capacity of the battery, without a second thought, and start treating home battery power like a disposable. The fact that some of these big batteries are floor-mounted and come with trolley wheels, tells me it shouldn't be that hard to swap them out while running on grid in the interim.

The usual disclaimer: Layman's opinion, personal 2c worth, use at own risk, to be adapted for your own situation, get professional advice.
On the first comment, that you are early risers, etc. I agree that people have their own routines, own usage patterns, and that the optimum solution in one case might not work or make sense for others. The idea of increasing the water temperature to 70 degrees might work for people who want to store as much heat energy as possible for evening baths & showers for the kids, but if you then have adults who want to freshen up with a morning shower, I'm not sure if that using the geyser as a battery is always a workable strategy. For those who need hot water first thing in the morning, there's this idea to run off battery, alternatively a heat pump could do that heating for the morning (and generally) more efficiently off battery and solar. Finally, what I'm doing, is running the geyser from the grid in the early morning, using a timer, while on an off-peak time-of-use tariff that's cheaper.
Back to the battery, though, I'm wondering if the concern about "using up the battery" on low-grade non-essential tasks like water heating really... yes I'm going to say it ... holds water. Firstly, if you need hot water in the morning for the family to wash and go to work, school, etc. then that to me is essential and time-critical. Beyond a point you can't shift all loads to the day.
Next, though, I'm wondering whether the cost of the battery is really such a big factor as it was before, from the point of view that the cost per kWh cycled in and out of the battery has come down dramatically. Just using this 15kWh battery as an example (and I'm sorry for harping on it, I'm not a spokesperson for it, I just like the concept on paper), then 80% cycling down times 6000 cycles gives a cost of around R0.40 per kWh. A third of what it used to be when I first bought. You can't run from the grid at that price. Okay, one should factor in the capacity loss and installation costs and go on full quotations, but say that it ups the cost to R0.80/kWh. You still can't buy power from Eskom at that price, so I'd say to let rip, run a 2kW or even a 3kW element, well within the 100A recommended discharge capacity of the battery, without a second thought, and start treating home battery power like a disposable. The fact that some of these big batteries are floor-mounted and come with trolley wheels, tells me it shouldn't be that hard to swap them out while running on grid in the interim.

@moolmanj I am totally off grid, like no connection to my house. I am on a farm, with the following setup:
15kw inverter
30kw battery capacity
30 x 450w panels
3 geysers on timers
3 fridges
2 deep freezers
2 borehole pumps x 750w
 
This works for me, but I still have to manage this. My batteries are full at about 1 PM, but when it is raining or cloudy this sometimes does not even reach full capacity. 
I would say Eskom is still the cheapest, but I never know of any outages or cable failures.
Right now I am on 84%, and tomorrow morning it will be at 60%, but sometimes on rainy days I have to start the generator to charge up to 60% before going to bed. 
Solar is not cheap, but it makes life easier, and then again, you will have to maintain and maybe replace in a few years. Sorry, back to your question, I definitely save because I had to pay connection rent of R3500 per month just for the connection. But in town Eskom stays the cheapest way, for now.
It all depends if you need hot water at night and in the morning, because these are the big energy eaters, geysers!

Just the usual 2c's worth of pure speculation. No, this is heavy overreaching speculation.
That being said, something on this graph looks unusual. The first circle on the left could be described as a transient export, but for the section circled on the right, it looks like export of around 1kW sustained over approximately 10-15 minutes (just eye-balling it), and that's rather a lot.
It just seems firstly like the energy balance is hard to maintain as the amount of PV generation at around 1500-2500W is fluctuating every so often, while consumption is also changing constantly but around the same levels of 1500-2500W. Throughout most of the day it seems like the battery can absorb the excess power well enough as it's charging.
But around where the SOC is close to 100%, as the expected battery charge rate should slow to a trickle charge, something else is happening. It's as if each time the battery is called upon to supply power during a PV dip (cloud?) during that period, then as soon as the demand on the battery stops and the charging re-commences, the exporting to grid starts and lasts around 10 minutes. It's as if the charge rate that the battery is capable of taking at that time is mismatched to the PV generation demanded, as if the inverter is signalling bulk charging requirements, while the battery's BMS is limiting charge to a trickle charge. Hence the exportation to grid of the excess.
My mind is wandering towards questions of battery and inverter compatibility, and I can see online that Goodwe has tested and certified the FreedomWon batteries with their inverter from a certain firmware version onwards, but even if that is done, maybe there's a case here where the firmware could be improved.
Or I could be entirely wrong and the the CT coil is placed wrongly.

The easiest way to test if you can cope without Eksdom is to turn off the main feed to your house, either at the kiosk outside or on your main DB. If you don’t have to turn it on again for a year, you know you are fine.

On an average day for an average user even in Winter you'll be fine, or you could make do. This is considering the 6.6kW of panels would generate around 20kWh, and you've got solar water heating and gas cooking to go with it, and you've got reasonable battery storage. On a clear Winter's day you could still get close to 30kWh if you had enough storage, but on heavy overcast days you might get just 5kWh. All thumbsucks based on personal usage along the Sunshine Coast.
So of course there will be days (sometimes several in a row) where cloud cover prevents meaningful power generation. Question is how you want to handle that, and the question then is what municipality you're in and what do they actually charge for grid fees? If it's Nelson Mandela Bay, for a grid-tied user on TOU it's around R117pm excl VAT. I don't think it's worth it to go off-grid in this case, if it means running a generator, but that's just me.

This is so true... and the most expensive kWh is the one you don't have when you need it...

Personal opinion to consider with caution only.
I see what you're trying to do, or why, but you can appreciate, I'm sure, that it's not precise, because your East/West configuration pulls your production earlier and later in the day, and flattens the peak production.
Perhaps if you do that, try to experiment with finding the peak forecasted value if you face all the panels East, and/or all the panels West. And then de-rate your Max Solar PV value in the SA setup, depending on the expected lower peak power generation that you see in those alternative forecasts. It could be for argument's sake that you say you've got 10% less PV, or 9000W estimated.
Most days the forecast won't matter much, if your battery is charged by 10am in the morning.

This doesn't confirm the question above: Are these panels connected all 4 electrically in parallel to each other? For that matter, considering the upper limit of the MPPT Range (30-115VDC), could it even be that they are all 4 connected electrically in series? Both of those configurations could be problematic. I think it's the first question that really has to be understood in full before it makes sense to look at anything else. It is not clear, not known with certainty based on what you've said so far, whether the panel set's Voltage is matching to the MPPT range in your installation. Do you have a wiring diagram you can post, or can you ask your installer? Maybe a spec sheet for your panel as well or the actual model code of the panel to go with it?
I was referring to the heat of the panels on the roof, not of the inverter, so that could be a separate issue. But if you can confirm that the panel configuration can be changed to a 2S2P (Two-Series, Two parallel), then the possible Voltage fluctuations with panel temperature would be less of an issue. The main issue is that in the worst case your MPPT input Voltage could be too close to the upper or lower limit of the MPPT range, so any fluctuations could push you out of the range.

Quickly back on-topic. All just speculation. Personal 2c worth is that I'd be cautious of adding another 5kW in parallel, from the point of view of the age of the product. Firstly the existing 5kW inverter should be just out of the normal warranty, and its expected remaining useful life is uncertain. Secondly, the older 5kW Deye seems to be close to the end of its model life-cycle, if a new 5kW model is already available, so future support could be anyone's guess. If you want to spend money now on upgrading the system in terms of capacity, I'd just look at spending money on a newer model at the same time for the long run. On a 60A supply if you don't intend to upgrade the inverter or panels, then the 8kW will be a good step up just to get a higher pass-through current. Otherwise if you have an 80A supply, or intend to upgrade your strings or battery bank significantly, I'd go higher for a 10kW.
You'd still have the option in any case of connecting the older 5kW Deye via AC coupling if you maybe transfer one string off it, to get some use out of it while it's still good, if you don't want to sell it.

Hello Everyone so here is a shot at it just as much facts without sounding Biased. I just went for the main brands and true hybrids in the market.
6kW Single-Phase Hybrid Inverter Comparison SA Market Facts
Solis S6-EH1P6K-L-PLUS / PRO / Advanced series
Tier status: Tier 1 (included in Bloomberg NEF Tier 1 inverter lists for Q1 2026 and prior periods; ranked in top positions in Wood Mackenzie global inverter reports, e.g., 5th in H1 2025 with strong residential and overall market presence).
Max PV input power: Typically 9.6–12kW+ usable (recommended array up to 12–19kW in some configurations).
MPPTs: 2 (wide range 90–435/520V, low startup ~90V, max current 16A+ per MPPT).
Battery charge/discharge: Up to 135A (some variants higher).
Backup output: 6kW continuous; surge/overload 200% for 10 seconds (~12kW momentary).
Switchover time: <4ms (UPS-level).
Backup efficiency: Battery-to-AC ~94–95% (overall inverter peak ~97.5%).
Generator integration: Supports via dedicated GEN port and utility/grid port (dual methods, auto start/stop dry contacts).
N-E bond: Built-in/automatic on backup port during grid loss (no external relay required in standard SA setups; configurable via grid code/standard settings).
Parallel: Up to 10 units (single/three-phase flexible, e.g., 60kW total).
Monitoring: SolisCloud (desktop/web version supports full remote management and settings changes; mobile app for basic viewing; some newer variants include onboard LCD/touch screen).
Firmware: Generally stable with minimal post-install updates required.
Noise factor: Natural convection (passive/fanless cooling in 6kW models; no fans in base design for quiet operation; higher-power variants may use intelligent fan cooling with variable activation; users report very low audible noise, fans rare even in hot conditions).
SA support: Free SOPs available; regular free training sessions/workshops via Solis Direct or via distributors.
Warranties: Standard 5 years (swap-out/replacement for valid claims; new or refurbished units at discretion, but SA practice favors full swap-out with brand new units); extended warranty purchasable (e.g., +5 years to total 10 years, or longer options up to 20 years in some models; no battery pairing required for extension eligibility; apply via Solis Cloud app or distributor within specified period, e.g., first 12 months).
Price range: ~R12,650–R25,000 (frequent specials/promos R12,650–R16,000; e.g., recent retailer listings at R12,650–R19,500 VAT incl. for certain models).
Deye SUN-6K-SG04LP1-EU (or SM2 variants)
Tier status: Mid-tier / emerging Tier 1 recognition (recognized as Tier 1 cleantech supplier in some S&P Global contexts; strong regional market presence but not consistently in top 10 of Wood Mackenzie or Bloomberg NEF global rankings).
Max PV input power: ~9.6kW usable (recommended array similar).
MPPTs: 2 (range ~125–425/500V, startup ~125V, max current ~13–17A per MPPT).
Battery charge/discharge: Up to 140A (some configs).
Backup output: 6kW continuous; surge/overload typically up to ~1.5–2x briefly (e.g., peak off-grid ~12kW for 10s in some references).
Switchover time: ~10ms typical.
Backup efficiency: Peak ~97.6% (MPPT >99%; battery-to-AC in high 90s%).
Generator integration: Via GEN port (dry contacts for auto start/stop; some dual input flexibility).
N-E bond: Not built-in; requires external relay/contactor (controlled via ATS port, dry contacts, or "Signal Island Mode" setting for off-grid activation; manuals specify external NO-type relay for N-PE bond in island mode).
Parallel: Up to 16 units (on-grid/off-grid).
Monitoring: SolarMan app (granular data, user-friendly for complex setups).
Firmware: Frequent updates for features/bugs (often related to battery BMS compatibility).
Noise factor: Intelligent/smart air cooling (internal fans; typically <30–55 dB depending on load; fans variable/slow/quiet in low-load scenarios, may activate briefly under heavy use/charging; community reports note warmer operation under sustained high loads/hot ambients, leading to DIY active cooling modifications like external fans or shrouds for better thermal management).
SA support: Large installed base; extensive community guides on Power Forum.
Warranties: Standard 5 years (repair or replacement at discretion); 10-year extended warranty available under specific conditions (e.g., paired with compatible batteries like certain lithium models; requires annual servicing, COC, and registration; some regions/models offer 10 years standard with battery pairing).
Price range: R18,000–R22,000 (often on sale).
Sunsynk 6kW (Lynks/standard hybrid – rebranded Deye)
Tier status: Mid-tier / emerging Tier 1 recognition (aligns with Deye; strong regional presence in SA/UK but not in top global rankings like Wood Mackenzie or Bloomberg NEF).
Specs largely match Deye hardware (e.g., PV/MPPT/battery currents/surge similar; peak efficiency ~97.6%).
Surge: Aligns with Deye (up to ~9,000W+ in some listings).
N-E bond: Matches Deye (not built-in; external relay required, often via ATS/signal for island mode).
Parallel: Up to 16 units.
Monitoring: Sunsynk Connect app (polished interface, clear graphs).
Noise factor: Matches Deye (intelligent/smart air cooling with internal fans; typically low/quiet <30–45 dB; fans may run briefly under load, some users report occasional noticeable noise or warmer casing in high-duty cycles).
SA support: Local tweaks (e.g., 10-year warranties on newer models); strong distributor network.
Warranties: Standard 5 years (repair or replacement at discretion); 10-year extended warranty available under specific conditions (e.g., paired with compatible batteries like Sunsynk, BSL, or IES models; automatic extension possible when inverter paired with qualifying battery within installation timeframe; requires COC and registration in SA).
Price range: R18,000–R24,000 (premium over base Deye equivalents).
Sungrow SH6.0RS
Tier status: Tier 1 (ranked top globally in Wood Mackenzie H1 2025 with score 93.7; No.1 bankable brand in Bloomberg NEF 2025 inverter survey with 100% recognition; consistently top-tier in market share and bankability).
Max PV input: High in some configs (e.g., up to ~13kW in related models).
MPPTs: 2 (standard range).
Battery charge/discharge: Standard for class.
Backup output: 6kW continuous; surge handling per load limits.
Switchover time: Standard.
Efficiency: Peak ~97.7%+.
Generator integration: Supported (details vary).
N-E bond: Per model specs (varies; follow local regs).
Parallel: Limited/not emphasized for this model (often max 3 in some regions).
Monitoring: Strong app/platform.
Noise factor: Natural convection (passive/fanless cooling; low noise <45 dB(A) typical; no fans in design for quiet operation).
SA support: Reliable brand compliance.
Warranties: Standard 10 years (repair or replacement at discretion); extensions available (e.g., up to 15 years on some products; no mandatory battery pairing noted for standard coverage).
Price range: R18,000–R22,000.
Growatt 6kW (SPH/ES Plus or SPF 6000 equivalents)
Tier status: Tier 1 recognition in some contexts (recognized as Tier 1 PV inverter supplier by S&P Global Commodity Insights; strong residential market share but mid-tier in some global rankings).
PV/MPPT: Decent dual (standard range).
Battery charge/discharge: Standard.
Backup: 6kW continuous; surge per model.
Parallel: Up to 6 units typical.
Efficiency: High 90s%.
Noise factor: Active cooling (fans; variable speed often PWM-controlled; users report noticeable/loud fan noise under load or constant in some scenarios; replacement with quieter fans possible).
SA support: Budget-oriented; mixed long-term feedback.
Warranties: Standard 2–5 years depending on model/region (repair or replacement at discretion; extensions possible within limited timeframes; no mandatory battery pairing for standard coverage).
Price range: R15,000–R20,000.
Luxpower 6kW Hybrid (e.g., GEN2-LB-EU/SNA6000)
Tier status: Mid-tier / value-focused (emerging brand; not typically in top global Tier 1 rankings like Wood Mackenzie or BloombergNEF; strong in budget/residential segments).
PV/MPPT: Competitive for price.
Battery charge/discharge: Good.
Backup: 6kW continuous; surge per model.
Parallel: Up to 10–16 units (varies by model).
Efficiency: Solid.
Noise factor: Active cooling (fans; <50 dB typical emission; fans activate on temperature/load rise; some users note variable noise depending on conditions).
SA support: Rising; value-focused.
Warranties: Standard 5 years (hybrid series; repair or replacement at discretion); extensions available (e.g., to 10 years purchasable or free/additional years with compatible battery pairing like HINAESS/Luxpower models; off-grid models shorter standard).
Price range: R7,500–R15,000 (aggressive).
Notes:
All models are NRS097-compliant for SA grid use.
N-E bond implementation varies: Some models feature built-in/automatic activation on backup during grid loss, while others require an external relay/contactor for off-grid activation to ensure proper grounding and compliance (follow local wiring regulations like SANS/CoC and installer advice).
Tier classifications can evolve with new reports (e.g., BloombergNEF quarterly, Wood Mackenzie biannual)
Noise/cooling: Passive/natural convection models are generally quieter (no fans), while active/intelligent fan models may produce audible noise under high load/temperature (often <30–50 dB; variable and load-dependent; some active-cooled models have community reports of warmer operation leading to DIY cooling enhancements like external fans).
Warranties are subject to conditions (e.g., installation by certified electrician, COC, registration, annual servicing in some cases); repair/replacement policies often at manufacturer/distributor discretion (swap-out common in SA for faster resolution). Battery pairing can unlock extensions in some brands, while others offer purchasable extensions independently.
Choices depend on priorities: e.g., surge/overload capability at 200% for 10 seconds is listed for one model, while others specify different surge levels; parallel capacity ranges from up to 6 units in some to up to 16 units in others; generator integration methods vary (e.g., dedicated GEN port plus utility port in one vs. GEN port in others).
Prices/stock fluctuate check retailers like PowerForum Store, for current specials, datasheets, and warranties.
Always use DC and AC SPD devices.

I have a bit of a different take personally. I view things from a ROI point of view. I would get 1 10kW and not care for redundancy. Why? Modern inverters last for years. Why have 2 to plan for an outcome that will happen once in say 5 years? If one is grid connected, use it. That is your silent generator right there. Will it kill a person to use the grid while getting a replacement inverter or the inverter repaired? I dont think so.

If one of the 2 inverters dies after 5 years and it cant be repaired, you are stuck with one small inverter and will be forced to buy 2 again. The other will be sold for next to nothing on the used market. I could see it working if the 1 10kW is that much more expensive than 2 5kW inverters which I am skeptical it is.

I have no redundancy for the inverter and am not grid connected and have no worries. But I operate from a perspective of not spending time or money on repairs. When the inverter fails, I get another one the same day or the following day and in 30 minutes I can install it. The broken inverter will probably be listed for sale and be of use to someone else willing to repair it and give it life again.
But I also dont/wont spend money on inverters that cost over 20k. I will stick to the Axpert clones that retail for cheap. I can get a 6.2kW for around 6k or a 11kw for around 10k. This is from brands that have been around for years now because I dont believe the big name brands last longer than the clones out there.

That is my take basically. I have no generator (I hate them) and have 1 inverter only. I spent 3300 on it and it has run flawlessly for a year. When the time comes as mentioned, I can purchase and install it in a matter of hours. For people grid connected, there is no reason in my opinion for the word redundancy to be a point of discussion unless it takes weeks/months for an inverter to get repaired and you have constant power cuts.

MTBF is a statistical measure, not a lifespan. It represents the average failure rate of a population, not how long a specific unit will last.
Putting two inverters in parallel does not halve their MTBF. Each unit still has the same failure rate, but system reliability improves because both units must fail before total loss occurs.
The real risk in parallel systems is not MTBF, but common-mode failures such as surges, battery faults, or wiring issues that can take out both units simultaneously.
In practice inverter failures are rarely random MTBF events. Most failures we see in the field are due to surges, heat, battery issues or installation faults. Running two inverters in parallel does improve resilience against small component failures like fans or relays, allowing the system to continue operating at reduced capacity. However, it does not protect against common-mode failures such as lightning, grid surges or battery faults, where both units are typically affected simultaneously.
So the real trade-off is not MTBF, but complexity vs partial redundancy. Proper surge protection, earthing and installation quality will have a far bigger impact on system reliability than choosing between 1×10kW or 2×5kW.

It's right there if you scroll a little further down the page.

All speculation. First check maybe if you've got a battery charge rate limit set to around 70A. The solar panels will only produce what the battery system demands.
Beyond that, I'm assuming your 7 panels are installed on one MPPT. Could obviously be wrong, I don't know. I'm wondering whether that inverter has set a limit on the power that one MPPT can produce. Considering the low start-up Voltage on your inverter, I'd try to spread the workload and experiment with connecting the panels in strings of 4 and 3 onto each MPPT and see if it makes a difference at mid-day. Three panels are obviously borderline on the low Voltage end, but the point would be to test if you can go above 3500W in total at noon when the Voltage is expected to be sufficient, and then you could consider based on what you see, whether to return to 7 in series, or add one panel to go 4+4.

I don't know the Deye menu system, but probably not. If that is the export limit of your solar, that is all the inverter is rated to transfer from DC to AC. The DC to DC charging of the battery should allow you to use more of the solar than the 5kW limit.

Yes, this is the AC coupling method as described above, and I guess you can read more about in the manual of the Deye under the Grid/Aux port operating modes. Basically the Deye inverter acts as a controller and creates a mini-grid. The Solis inverter will respond to the grid signal from the Deye, generate power and the Deye inverter will then charge the battery connected as normal.

I wouldn't do that as a first choice. The inverter can in theory connect up to 10,400W of panels. Now I understand that it's a mixed bag of panels, but I'd start by maybe listing what you've got by make and model of the panels, and then seeing if one can come up with a configuration that could allow you to add that 4kW of panels without resorting to another MPPT. If it's a forlorn hope, if it doesn't work, then so be it, or if you've already gone through the thought process and concluded that you need the MPPT solution, that's something else, but from what you've written, I'd at least ask if this is an option.

I wouldn't do that as a first choice. The inverter can in theory connect up to 10,400W of panels. Now I understand that it's a mixed bag of panels, but I'd start by maybe listing what you've got by make and model of the panels, and then seeing if one can come up with a configuration that could allow you to add that 4kW of panels without resorting to another MPPT. If it's a forlorn hope, if it doesn't work, then so be it, or if you've already gone through the thought process and concluded that you need the MPPT solution, that's something else, but from what you've written, I'd at least ask if this is an option.

I wouldn't do that as a first choice. The inverter can in theory connect up to 10,400W of panels. Now I understand that it's a mixed bag of panels, but I'd start by maybe listing what you've got by make and model of the panels, and then seeing if one can come up with a configuration that could allow you to add that 4kW of panels without resorting to another MPPT. If it's a forlorn hope, if it doesn't work, then so be it, or if you've already gone through the thought process and concluded that you need the MPPT solution, that's something else, but from what you've written, I'd at least ask if this is an option.

Yes, this is the AC coupling method as described above, and I guess you can read more about in the manual of the Deye under the Grid/Aux port operating modes. Basically the Deye inverter acts as a controller and creates a mini-grid. The Solis inverter will respond to the grid signal from the Deye, generate power and the Deye inverter will then charge the battery connected as normal.