Hi everyone. I'm looking for some advice on upgrading my solar system and would really appreciate your recommendations.

My current setup is:

• 5kW GoodWe inverter

• 19 × 330W solar panels (6.27kW total)

• 10kWh Pylontech battery

The 5kW inverter is my limitation. My goal is to be able to run appliances like the dishwasher, inverter air conditioners, kettle, 2kW geyser, washing machine and iron at the same time during the day without constantly having to manually manage loads or being restricted.

I also want to maximise my solar usage and minimise my reliance on the grid.

I'm considering:

• Adding another 10 × 620W bifacial panels.

• Upgrading to a 10-12kW inverter.

My questions are:

1. Is it better to keep my existing 5kW GoodWe and add a second inverter, or replace it with a single larger inverter?

2. Is GoodWe still one of the best options, or should I be looking at brands like Deye, Sunsynk, Victron, Huawei or something else? Price is a factor

3. Would adding another 10 × 620W bifacial panels be the right move, and what inverter size would you recommend for this setup?

4. I currently have a 10kWh Pylontech battery. What is the optimal battery strategy? Should I mainly reserve it for night-time use, or should I allow it to discharge during the day whenever PV can't fully meet demand to avoid importing from the grid?

5. At the moment, I only use the battery between 10:00pm and 4:00am. From sunset until 10:00pm I use grid power, and again from 4:00am until the PV starts producing in the morning. Is this the most efficient way to operate the battery, or would I save more by using the battery differently during the day and evening?

My objective is to maximise self-consumption from solar, minimise grid usage, and still preserve battery life. I'd really appreciate any recommendations or experiences from people who have upgraded similar systems. Thanks!

1) If you are adding a second inverter to the current one then the current inverter must be able to work in parallel with the new inverter so in order for the current inverter to work in parallel it must be the exact same inverter model and the same firmware version and I doubt that the exact same model is still available for purchase.

2) The brand of inverter is dictated by what functions the inverter must perform like feedback to the grid or feedback to non essential loads when there is enough PV power available to power those loads so ask yourself the question would the features that the inverter can provide be utilised or not.

3) The PV power is also dictated by the inverter chosen so first look at the inverters available on the market and then you design your system around that, also remember that there must be enough roof space or space available to mount the solar panels.

4) I would reserve the battery for night time use depending on the loads connected to the inverter.

5) What is the SOC of the battery at 4:00 am, if the SOC is still above 50% then I would increase that time to 5:00 am or 6:00 am or even 7:00 am depending how early the charger kicks in.

Also remember that the Pylontech batteries are 0.5C so that means that the battery can only charge or discharge at a rate of half of the current e.g. the UP5000 is 5120 Wh and the voltage is 48V so half of 5120 Wh is 2560 Wh and 2560/48 is 53A so in battery mode the maximum load per battery is half of the total Wh of that battery.

I had a quick look at the inverters that The Powerforum Store is selling and there are 2 Solis models which are standing out the Solis S6 Pro 6kW Plus Hybrid Inverter 10 Year Warranty With Display available @ R13843.70 incl vat and the Solis S6 12kW Single Phase Low Voltage Hybrid Inverter (S6-EH1P12K03-NV-YD-L) 10 Year Warranty With Display available @ R34672.50 incl vat

Personally I would opt for 2 of the 6Kw units that work in parallel rather than one 12Kw unit and with the money that is saved buy another battery or more solar panels.

The Solis 6Kw unit has a Maximum usable PV input power of 9.6Kw and the 12Kw unit has a Maximum usable PV input power of 19.2Kw so there is room for upgrade just remember that the Solis inverters has more than one PV input and the total power quoted above are for all the inputs and the solar panels must be configured accordingly.

6 hours ago, xinath said:

Hi everyone. I'm looking for some advice on upgrading my solar system and would really appreciate your recommendations.

My current setup is:

• 5kW GoodWe inverter

• 19 × 330W solar panels (6.27kW total)

• 10kWh Pylontech battery

The 5kW inverter is my limitation. My goal is to be able to run appliances like the dishwasher, inverter air conditioners, kettle, 2kW geyser, washing machine and iron at the same time during the day without constantly having to manually manage loads or being restricted.

I also want to maximise my solar usage and minimise my reliance on the grid.

I'm considering:

• Adding another 10 × 620W bifacial panels.

• Upgrading to a 10-12kW inverter.

My questions are:

1. Is it better to keep my existing 5kW GoodWe and add a second inverter, or replace it with a single larger inverter?

2. Is GoodWe still one of the best options, or should I be looking at brands like Deye, Sunsynk, Victron, Huawei or something else? Price is a factor

3. Would adding another 10 × 620W bifacial panels be the right move, and what inverter size would you recommend for this setup?

4. I currently have a 10kWh Pylontech battery. What is the optimal battery strategy? Should I mainly reserve it for night-time use, or should I allow it to discharge during the day whenever PV can't fully meet demand to avoid importing from the grid?

5. At the moment, I only use the battery between 10:00pm and 4:00am. From sunset until 10:00pm I use grid power, and again from 4:00am until the PV starts producing in the morning. Is this the most efficient way to operate the battery, or would I save more by using the battery differently during the day and evening?

My objective is to maximise self-consumption from solar, minimise grid usage, and still preserve battery life. I'd really appreciate any recommendations or experiences from people who have upgraded similar systems. Thanks!

I agree with Gerhard.

Just to add a bit. Your biggest issue with your current system is the geyser sitting on the inverter. You have a small 2kW element so for at least 4 hours during the day you only have less than 3kW of inverter capacity.

On my side I have a 5kW that supplies the whole house between 9am and 3pm. My 3.6kW gets charged by the 5kW during that time. At which point my 3.6kW takes over its own circuits as my DB is split. So half the DB is supplied by 3.6kW and other high power circuits (kitchen and oven) are supplied by the 5kW.

The reason I have no issues with overloading etc is because I have the full 5kW available for those 6 hours as my geyser is not on the inverter. It gets supplied by a Geyser controller on its own array.

I had the same setup as you but I lasted a month keeping the geyser on the inverter as it just requires too much management. Especially as I’m offgrid.

Geysers don’t belong on any inverter less than 8kW and array less than 6.5kW.

7 hours ago, GerhardK83 said:

1) If you are adding a second inverter to the current one then the current inverter must be able to work in parallel with the new inverter so in order for the current inverter to work in parallel it must be the exact same inverter model and the same firmware version and I doubt that the exact same model is still available for purchase.

2) The brand of inverter is dictated by what functions the inverter must perform like feedback to the grid or feedback to non essential loads when there is enough PV power available to power those loads so ask yourself the question would the features that the inverter can provide be utilised or not.

3) The PV power is also dictated by the inverter chosen so first look at the inverters available on the market and then you design your system around that, also remember that there must be enough roof space or space available to mount the solar panels.

4) I would reserve the battery for night time use depending on the loads connected to the inverter.

5) What is the SOC of the battery at 4:00 am, if the SOC is still above 50% then I would increase that time to 5:00 am or 6:00 am or even 7:00 am depending how early the charger kicks in.

Also remember that the Pylontech batteries are 0.5C so that means that the battery can only charge or discharge at a rate of half of the current e.g. the UP5000 is 5120 Wh and the voltage is 48V so half of 5120 Wh is 2560 Wh and 2560/48 is 53A so in battery mode the maximum load per battery is half of the total Wh of that battery.

I had a quick look at the inverters that The Powerforum Store is selling and there are 2 Solis models which are standing out the Solis S6 Pro 6kW Plus Hybrid Inverter 10 Year Warranty With Display available @ R13843.70 incl vat and the Solis S6 12kW Single Phase Low Voltage Hybrid Inverter (S6-EH1P12K03-NV-YD-L) 10 Year Warranty With Display available @ R34672.50 incl vat

Personally I would opt for 2 of the 6Kw units that work in parallel rather than one 12Kw unit and with the money that is saved buy another battery or more solar panels.

The Solis 6Kw unit has a Maximum usable PV input power of 9.6Kw and the 12Kw unit has a Maximum usable PV input power of 19.2Kw so there is room for upgrade just remember that the Solis inverters has more than one PV input and the total power quoted above are for all the inputs and the solar panels must be configured accordingly.

Thanks for the detailed feedback.

1. If adding a second inverter means it has to be the exact same model and firmware version to operate in parallel, then it sounds like that's not really a viable option.

2. I do need the ability to feed excess PV power to my non-essential loads, my goal is to maximise solar usage rather than leaving generation unused.

3. Noted. It makes sense to choose the inverter first and then design the PV array around its capabilities, while also considering the available roof space.

4. I agree with reserving the battery for night-time use.

5. At 4:00 am my battery is typically still at around 76% SOC. Based on that, I can probably push it out to 6:00 am, or even later.

6. Just to add my current system provides 50% - 55% of usage...but I always have to ensure that whilst the geyser is heating we can only use one other heavy appliance. The house in general with anything else on runs on 500w.

Regarding your recommendation of two 6 kW units instead of a single 12 kW unit, I have a few questions. If I go that route, would I need to split my house wiring between the two inverters and decide in advance which circuits or appliances are connected to each one? Or do the two inverters communicate and function as a single system with unified monitoring and management? My concern is having to manage two separate systems or monitor two different sets of data.

At the moment, my entire house is connected to the essential loads output, so I manually manage what runs at any given time. Ideally, I'd like to move away from that and have a system that manages everything more intelligently.

I've had my Goodwe for eight years now, and it has been very reliable. It's been quiet, dependable and has never given me any issues, so naturally I'm inclined to stick with what I know. That's why I was asking whether the Goodwe 12 kW would still be a good option today, or whether the Solis S6 Pro has significantly surpassed both Goodwe and Sunsynk in terms of features, performance and long-term value.

When I originally installed the Goodwe, my priorities were reliability during load shedding and reducing my electricity costs. Since then, my kids have grown, our household demand has increased considerably and our needs have changed.

This will probably be the last major upgrade I make and God willing, I'd like it to last the next 20 years. My priority is a system that is reliable, easy to manage, and capable of running the house without me constantly checking settings or manually managing loads.

5 hours ago, Denns said:

I agree with Gerhard.

Just to add a bit. Your biggest issue with your current system is the geyser sitting on the inverter. You have a small 2kW element so for at least 4 hours during the day you only have less than 3kW of inverter capacity.

On my side I have a 5kW that supplies the whole house between 9am and 3pm. My 3.6kW gets charged by the 5kW during that time. At which point my 3.6kW takes over its own circuits as my DB is split. So half the DB is supplied by 3.6kW and other high power circuits (kitchen and oven) are supplied by the 5kW.

The reason I have no issues with overloading etc is because I have the full 5kW available for those 6 hours as my geyser is not on the inverter. It gets supplied by a Geyser controller on its own array.

I had the same setup as you but I lasted a month keeping the geyser on the inverter as it just requires too much management. Especially as I’m offgrid.

Geysers don’t belong on any inverter less than 8kW and array less than 6.5kW.

Yes the issue is the geyser on the inverter, which i agree. I did look at the option you have…. of having the geyser controller on its on array, however, given that our needs have grown, I looked at perhaps just increasing the inverter capacity and leaving the geyser as is. Well at least I think that would suit be better but I could be wrong.

 

7 minutes ago, xinath said:

Regarding your recommendation of two 6 kW units instead of a single 12 kW unit, I have a few questions. If I go that route, would I need to split my house wiring between the two inverters and decide in advance which circuits or appliances are connected to each one? Or do the two inverters communicate and function as a single system with unified monitoring and management? My concern is having to manage two separate systems or monitor two different sets of data.

The AC inputs as well as the AC outputs on the inverters are in parallel and the inverters communicate with each other to share the load between them.

https://www.solisinverters.com/uploads/file/Solis_Manual_S6-EH1P(3-8)K-L-PLUS_EUR_V1,3(20260402).pdf

P34 in the manual has a nice diagram which illustrates how the inverters are used in parallel.

Do you have the label of the 330W solar panels currently in use which indicates the voltage and current of each solar panel?

If you put a LCR / ECR (load/energy control relay) on your geyser it will switch off the geyser automatically if the house pulls more than a preset value and switch it on again when that load reduces.