March 24, 20251 yr Hi all, I'm planning on upgrading my solar setup to 2 x 12kW 3-phase inverters connected in parallel. I live on a smallholding with 3-phase Eskom power and run a borehole and other pumps that are 3-phase. We have two dwellings so the 24kW total capacity will be great. The reason for two 12kW inverters instead of one big one is that I get 4 MPPTs rather than two which is good as I have a complex roof layout and will need more than 2 strings to make the most of my roof space. Also redundancy. I aim to be able to go effectively off-grid in summer and on sunny winter days to save costs. I'm in the Western Cape. I'm looking at the Deye and the Sunsynk units. They seem pretty similar but my installer prefers Deye as he has good experience with their service centre. Does anyone have any experience, insights, war stories of either of these two options to share? Which would you prefer?I see that Deye have a new version of their inverters and the international websites show that the 12kW 3ph is also updated, but that's not available here yet. Is it worth waiting for or should I take advantage of the deals on the current version? The specs look very similar except for the total PV input power which is quite a bit more on the new version, but with my roof space I won't really be able to take advantage of that. Much appreciated.
March 24, 20251 yr 50 minutes ago, openmind said:Hi all, I'm planning on upgrading my solar setup to 2 x 12kW 3-phase inverters connected in parallel. I live on a smallholding with 3-phase Eskom power and run a borehole and other pumps that are 3-phase. We have two dwellings so the 24kW total capacity will be great. The reason for two 12kW inverters instead of one big one is that I get 4 MPPTs rather than two which is good as I have a complex roof layout and will need more than 2 strings to make the most of my roof space. Also redundancy.I aim to be able to go effectively off-grid in summer and on sunny winter days to save costs. I'm in the Western Cape.I'm looking at the Deye and the Sunsynk units. They seem pretty similar but my installer prefers Deye as he has good experience with their service centre.Does anyone have any experience, insights, war stories of either of these two options to share? Which would you prefer?I see that Deye have a new version of their inverters and the international websites show that the 12kW 3ph is also updated, but that's not available here yet. Is it worth waiting for or should I take advantage of the deals on the current version? The specs look very similar except for the total PV input power which is quite a bit more on the new version, but with my roof space I won't really be able to take advantage of that.Much appreciated.In a way personnel choice but reviews indicate better service levels from Deye. Worth the wait? Again your call but as you say you will not need the extra power from panels.
March 24, 20251 yr 5 hours ago, openmind said:Also redundancyTwo smaller units offer redundancy but probably twice the hassle in other regards.If you go for the 30kW high voltage unit, you can use thinner cables.
March 24, 20251 yr If you get a 30kW HV unit, you will have 4 MPPT's anyway, and a lot less trouble with battery wiring, as @frivan says.Here is a spec sheet.:- Sunsynk_ThreePhaseHI_29.9-50K_Datasheet_v15_English.pdf
March 25, 20251 yr Author Thanks for your insights, food for thought. I did not realise the HV inverters have more than 2 MPPT inputs.
March 25, 20251 yr The 12kW 3ph units can actually accomodate 3 strings, even though it only has 2 MPPT's. One just need to make sure that the 2 strings in parallel is in the same direction.Depending on how many kW (and units) of battery you are installing, HV may be a much easier install.
March 25, 20251 yr 7 minutes ago, Sidewinder said:The 12kW 3ph units can actually accomodate 3 strings, even though it only has 2 MPPT's. One just need to make sure that the 2 strings in parallel is in the same direction.Depending on how many kW (and units) of battery you are installing, HV may be a much easier install.Good info. Just wonder why you mention the 2 strings in parallel to be in the same direction. Although the strong 1 of the 2 will provide more amps the voltage to both would be close enough to warrant even different directions for them. This is the beauty of being able to use parallel. For this reason campers prefer parallel due to the good chance that 1 string could hit shade.
March 25, 20251 yr 44 minutes ago, Sidewinder said:One just need to make sure that the 2 strings in parallel is in the same direction.Sorry wrong, they only need to have to same amount of panels in series each and thus same Voltage levels...35 minutes ago, Scorp007 said:Although the strong 1 of the 2 will provide more amps the voltage to both would be close enough to warrant even different directions for them.correctI reckon the cost of HV batteries make them a less likely candidate for the average home user, maybe @openmind is a well above average home user with lots more dosh to spend :-) depending on your power peak consumption etc. looking at a HV system may well be worthwhile, I'll stick to my 51.2V nominal battery Voltage setup, thank you very much (with 30-odd kWh usable power on tap)...
March 25, 20251 yr Author 32 minutes ago, Kalahari Meerkat said:Sorry wrong, they only need to have to same amount of panels in series each and thus same Voltage levels...correctI reckon the cost of HV batteries make them a less likely candidate for the average home user, maybe @openmind is a well above average home user with lots more dosh to spend :-) depending on your power peak consumption etc. looking at a HV system may well be worthwhile, I'll stick to my 51.2V nominal battery Voltage setup, thank you very much (with 30-odd kWh usable power on tap)...Haha, not spending more than I need to - I'm on a smallholding with two dwellings and a three-phase borehole pump (and other pumps) so I need more kW (and kWh) than average. I just did some rough calcs and based on online prices, I can do a single inverter 30kW 3ph high-voltage setup with 20kWh of battery (4x5kWh @ 50V in series to give 200V to the inverter that needs 160V min) for about only 10% more cost than my original 2 x 12kW 3ph low-voltage solution (all Deye products). So HV is very much an option. Still learning though so may have missed something. My installer is looking at the details and I will report back.
March 25, 20251 yr 48 minutes ago, openmind said:30kW 3ph high-voltage setup with 20kWh of batteryImmediately some are likely to jump in here and tell you that you should have at least 30kWh @ 1C battery if you have a 30kW inverter, which is semi-true, if you are likely to get to 30kW peak consumption, then you should have batteries to match, unless your batteries can happily run at 1.5C or more, be aware, assuming the batteries are 1C, you should not exceed 20kW power consumption when running off batteries...also the 4 X 50V in series, normally require some sort of management interface, which I hope is in your quote/calculations... I have not looked at HV setups myself properly yet, 200+V DC with 100+Amps behind it, scares me somewhat. so I'll stick with the also potentially lethal 50-odd Volt setup instead...
March 25, 20251 yr @openmind ,Just be careful regarding serial batteries. Most of the standard batteries can't be serialized, only parallel. The only make that I've come across so far that can do both is the Weco ones. There may well be others.Most HV stacks that I've seen (Deye) has a "controller hub" thingy on top.
March 25, 20251 yr Author 2 hours ago, Kalahari Meerkat said:Immediately some are likely to jump in here and tell you that you should have at least 30kWh @ 1C battery if you have a 30kW inverter, which is semi-true, if you are likely to get to 30kW peak consumption, then you should have batteries to match, unless your batteries can happily run at 1.5C or more, be aware, assuming the batteries are 1C, you should not exceed 20kW power consumption when running off batteries...also the 4 X 50V in series, normally require some sort of management interface, which I hope is in your quote/calculations... I have not looked at HV setups myself properly yet, 200+V DC with 100+Amps behind it, scares me somewhat. so I'll stick with the also potentially lethal 50-odd Volt setup instead...Ah, yes, thanks, looks like I'll need 6 batteries with a 30kW inverter (they seem to be 1C). Eish.Yes, the HV batteries are designed to operate in series with a BMU which I have in my calcs. The 20kW HV unit is looking more doable, smaller, cheaper, fewer batteries...
March 25, 20251 yr Author 2 hours ago, Sidewinder said:@openmind ,Just be careful regarding serial batteries. Most of the standard batteries can't be serialized, only parallel. The only make that I've come across so far that can do both is the Weco ones. There may well be others.Most HV stacks that I've seen (Deye) has a "controller hub" thingy on top.Yes, the Deye HV batteries are designed to be serialised with a BMU controller - like this: https://sp-energy.co.za/product/deye-battery-61-44kwh-hv-bos-g-set/
March 25, 20251 yr 4 minutes ago, openmind said:Ah, yes, thanks, looks like I'll need 6 batteries with a 30kW inverter (they seem to be 1C). Eish.You are under no obligation to buy batteries to suit your inverter size. Often it is recommended to go for an inverter that is suited for future needs. The solar and batteries can be expanded later. If you overload your batteries, the inverter will just switch off.
March 25, 20251 yr My 2c would be to start with say 4 batteries due to the cost. Learn to use the features of the inverter. Make hay while the sun is shining even more so with the heat generated items or pumps and monitor the SOC. For those with grid use a highish SOC and set the timer to use grid if available. The decide within a few months if more battery power is needed.
March 25, 20251 yr The HV inverters normally have 2x battery connections, each connection can only accommodate 50A and the Voltage according to number of batteries. Depending on battery type, you can duel feed to both connections, therefor having 100A, if a battery parallel port check box is ticked on the inverter.Notice the duel output and convenient stacking of these batteries. Also can easily handle the 50A+50A current draw if needed.https://bslbatt.co.za/wp-content/uploads/2024/01/ESS-GRID-HV-PACK-231118.pdf Edited March 25, 20251 yr by TimCam
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