Newby checking in and asking questions re new system.

[Nuts4Solar]

I've been measuring our power usage over the past few months and, despite using induction cooking, we have got our average daily power usage down to about 8-10kwh a day. About 5-6 kwh overnight.

The exception is maybe once a week when our usage will peak at 13kwh a day due to a lot of cooking - and having just renovated have no plans for gas.

I want to keep the cooker connected to the inverter so we can cook and most importantly making morning coffee when the power is out.

Because of this we will peak above 5.5kw up to 6.5kw for 10 minutes or so several times a week.

We also have a solar geyser with a 2kw element that we switch on when it is cloudy or raining which may bring our usage up to 13-15kwh a day.

I'm interested in some input or critique on what I am planning, that we expand in the future if needed.

- JA Solar 6x540 watt panels

- 5.5kw Sunsynk inverter. 

This is where I have a real questions. I've had many quotes and half a dozen companies tell me that as long as the power from the grid is on, the 5.5kwh inverter will be able to supply up to 7kw of power for a sustained amount of time - in my case maybe 10-20mins. The other half of companies say that the 5,5kw can't and I require an 8kw inverter.

Can anybody give me a definitive answer on this?

- Hubble 5.5kw Lithium or 2 x Pylontech 3.5kwh lithium.

Can anyone help?

 

 

 

 

[Achmat]

6 minutes ago, Nuts4Solar said:

I've been measuring our power usage over the past few months and, despite using induction cooking, we have got our average daily power usage down to about 8-10kwh a day. About 5-6 kwh overnight.

The exception is maybe once a week when our usage will peak at 13kwh a day due to a lot of cooking - and having just renovated have no plans for gas.

I want to keep the cooker connected to the inverter so we can cook and most importantly making morning coffee when the power is out.

Because of this we will peak above 5.5kw up to 6.5kw for 10 minutes or so several times a week.

We also have a solar geyser with a 2kw element that we switch on when it is cloudy or raining which may bring our usage up to 13-15kwh a day.

I'm interested in some input or critique on what I am planning, that we expand in the future if needed.

- JA Solar 6x540 watt panels

- 5.5kw Sunsynk inverter. 

This is where I have a real questions. I've had many quotes and half a dozen companies tell me that as long as the power from the grid is on, the 5.5kwh inverter will be able to supply up to 7kw of power for a sustained amount of time - in my case maybe 10-20mins. The other half of companies say that the 5,5kw can't and I require an 8kw inverter.

Can anybody give me a definitive answer on this?

- Hubble 5.5kw Lithium or 2 x Pylontech 3.5kwh lithium.

Can anyone help?

 

 

 

 

The sunsynk has a pass through of 35A so if the grid is available or will provide about 8kw to the connected loads.

I have the 8kw and pass through is a lot higher at 90A and have witnessed it go to 11kw. 

The 5kw sunsynk should be fine for your needs. 

Edit 

And Hubble will give you the full 5.5kw vs the pylontech which will limit you to 3.5kw.

Hubble batterye are 1C and pylontech are 0.5C rated. 

Edited May 19, 2021 by Achmat

[Nuts4Solar]

8 minutes ago, Achmat said:

The sunsynk has a pass through of 35A so if the grid is available or will provide about 8kw to the connected loads.

I have the 8kw and pass through is a lot higher at 90A and have witnessed it go to 11kw. 

The 5kw sunsynk should be fine for your needs. 

Brilliant, thanks. You've helped me eliminate several companies too! Making my job much easier. cheers

[Buyeye]

I would suggest another string of 6 making it 12 panels to save on the installation costs. But you can always add them later.

[Nuts4Solar]

37 minutes ago, Buyeye said:

I would suggest another string of 6 making it 12 panels to save on the installation costs. But you can always add them later.

Wouldn't that be way more power than I need? We use a max of 10kwh a day and during the day when working about 350watts an hour max. And I'd probably install the panels myself and have my electrician do the sparky bits. But I'm happy to be pursuaded otherwise.

[Tariq]

I have the 5 kW Sunsynk and with grid available have gone up to 7.65 kW total load ( essential and non essential circuits) for probably over an hour ( tumble dryer)

 I have 2.1 kWp facing NE and 2.1 kWp facing NW in Cape Town, i definitely feel the need for more panels, but roof space is a constraint, by the way we have a gas stove, but the geyser is connected to the inverter

Edited May 19, 2021 by Tariq

[Nuts4Solar]

3 minutes ago, Tariq said:

I have the 5 kW Sunsynk and with grid available have gone up to 7.65 kW

That's good to hear that it can take that load. I feel more confident now.

We are lucky enough to be up on a hill in Johannesburg with a north facing roof. I figured start at the minimum and add some more panels if we feel we need them.

 

[Tariq]

Summer you will probably get about 15 kWh from the panels and winter probably 11 kWh per day

[Achmat]

10 minutes ago, Nuts4Solar said:

That's good to hear that it can take that load. I feel more confident now.

We are lucky enough to be up on a hill in Johannesburg with a north facing roof. I figured start at the minimum and add some more panels if we feel we need them.

 

You should size your panels for winter production. 

In summer I'm getting 65kwh per day which is way more than I need but with my first winter, even in full sunny days I'm only getting 28 to 30kWh. 

You can also use an app called PV solar forecast. The free version will give you potential solar production in the next 3 days based on weather forecasts and your system. 

This is for my setup. It's pretty accurate. 

[Peter Topp]

Hi Achmed

Please explain what you mean by 35A  or 90A on a 5KW or 8Kw Sunsynk inverter . Is this all to load utilities?

To me If you pass through 90A on a 8kw inverter to the load  and the mains fail  it would mean about 450A  draw from the battery if it is all to the utilities or am I confused.

To me passthrough for the 8KW would mean battery max charge of about 38A and max load of  about 38A not a output load to utilities and not 90A to utilities.

To me passthrough for the 5KW would mean battery max charge of about 24A and max load of  about  24A not a output load to utilities and not  35A to utilities.

Edited May 19, 2021 by Peter Topp

[Achmat]

15 minutes ago, Peter Topp said:

Hi Achmed

Please explain what you mean by 35A  or 90A on a 5KW or 8Kw Sunsynk inverter . Is this all to load utilities?

To me If you pass through 90A on a 8kw inverter to the load  and the mains fail  it would mean about 450A  draw from the battery if it is all to the utilities or am I confused.

To me passthrough for the 8KW would mean battery max charge of about 38A and max load of  about 38A not a output load to utilities and not 90A to utilities.

To me passthrough for the 5KW would mean battery max charge of about 24A and max load of  about  24A not a output load to utilities and not  35A to utilities.

Pass through is the max load on the ups port of the inverter. 

If grid fails during this the inverter will trip as the inverter 5/8kw depending on model and double this for 10 seconds. 

 

Pic below of the inverter charging batteries from grid and supplying the load connected to the inverter. 

[Peter Topp]

Hi Achmat

Your picture shows exactly what I said max of about 10Kw  which is 5Kw battery+ 5Kw Load  220v x (24A +24A).

The ups to me only supports excess power and will be limited.

The explanation you have given defies the limitation of the inverter  and would be in alarm mode if you draw that amount of current.

 

 

[Tariq]

@Achmat, assume your pv production drop of over 50% is probably due to your panels being mounted flat on the carport 

[Achmat]

13 minutes ago, Peter Topp said:

Hi Achmat

Your picture shows exactly what I said max of about 10Kw  which is 5Kw battery+ 5Kw Load  220v x (24A +24A).

The ups to me only supports excess power and will be limited.

The explanation you have given defies the limitation of the inverter  and would be in alarm mode if you draw that amount of current.

 

 

Pass through is a feature found in many inverters. 

Will try and run another test with better graphs. 

My whole house is om load pretty of the inverter with no loads before the inverter or on the aux port. 

[Achmat]

2 minutes ago, Tariq said:

@Achmat, assume your pv production drop of over 50% is probably due to your panels being mounted flat on the carport 

Correct 

[Leshen]

33 minutes ago, Brani said:

In my opinion, neither.

but let’s not sidetrack from inverter question

Hi Brani. What battery would you recommend?

 

[Achmat]

31 minutes ago, Peter Topp said:

Hi Achmat

Your picture shows exactly what I said max of about 10Kw  which is 5Kw battery+ 5Kw Load  220v x (24A +24A).

The ups to me only supports excess power and will be limited.

The explanation you have given defies the limitation of the inverter  and would be in alarm mode if you draw that amount of current.

 

 

Running 3 aircons, kettle, tumble dryer and well point pump plus our normal household load all on the ups port of the inverter. 

Obviously if the grid were to go down at this point then the inverter will trip as the battery plus solar will not be able to supply for the full load for more than 10 seconds. 

[Leshen]

19 minutes ago, Peter Topp said:

Hi Achmat

Your picture shows exactly what I said max of about 10Kw  which is 5Kw battery+ 5Kw Load  220v x (24A +24A).

The ups to me only supports excess power and will be limited.

The explanation you have given defies the limitation of the inverter  and would be in alarm mode if you draw that amount of current.

 

 

Hi Peter. See attached pic showing inverter passthrough. Here you have 8000w being produced from a combo of battery and PV and the remainder 1200w passes through the inverter from the grid to supply the essential load. So total load on essential side is 9200w. 
 

You have 33.6A from DC to AC and a further 5.1A from the grid. The passthrough function is at a max of 90A which is a sum of 34A from DC to AC and 56A from the Grid which can passthrough the inverter.  All these current measurements are at 235V so not to confuse it with battery or PV current. 
 

The passthrough feature is on the load side of the inverter. The grid side will be supplemented directly from the Grid if needs be.

Even though the inverter is capable of drawing a further 56A on the load side, it’s not recommended to install high draw items ie geysers, stoves etc on this side as it’s not good practice to draw say 11000w on the essential/load side when Eskom goes offline. This puts the inverter in fault mode which isn’t good practice. 

[Peter Topp]

Hi

I agree that that is from three sources however should there be no power from mains or pv the battery or  inverter cannot sustain that power and therefor this setup would not be normal and the current is just on about 41amps which is about the about the max limit of the inverter not 90amps.Some members think that would be able to pass through the 90A from mains as I have had this discussion in other posts. 

A member had bought a 2KW inverter to handle 60A amps because of the passthrough spec.

 

Edited May 19, 2021 by Peter Topp

[Leshen]

4 minutes ago, Peter Topp said:

Hi

I agree that that is from three sources however should there be no power from mains or pv the battery or  inverter cannot sustain that power and therefor this setup would not be normal and the current is just on about 41amps which is about the about the max limit of the inverter not 90amps.Some members think that would be able to pass through the 90A from mains as I have had this discussion in other posts. 

A member had bought a inverter to handle 3KW to handle 60A amps because of the passthrough spec.

 

Remember that the 34A also passes through the inverter 

[Peter Topp]

Hi I understand that however a inverter is also for load shedding and cannot sustain 90A loads as suggested.

[Achmat]

3 minutes ago, Peter Topp said:

Hi

I agree that that is from three sources however should there be no power from mains or pv the battery or  inverter cannot sustain that power and therefor this setup would not be normal and the current is just on about 41amps which is about the about the max limit of the inverter not 90amps.Some members think that would be able to pass through the 90A from mains as I have had this discussion in other posts. 

A member had bought a inverter to handle 3KW to handle 60A amps because of the past5hrough spec.

 

Pass through spec only applies if the grid is available and used in many applications so that you do not need to split your loads. 

Shipping and boats use this feature a lot more where they don't have to disconnect their loads from the inverter when the connect to shore power of their inverter can pass through. 

It's also useful in off grid installations where you don't have the grid but you could connect a 12kw generator to the grid port so the generator can supply this and pass through the inverter. 

[Achmat]

Just now, Peter Topp said:

Hi I understand that however a inverter is also for load shedding and cannot sustain 90A loads as suggested.

But its not only for load shedding which I think you are missing. We just tend to think of inverters on terms of load shedding. 

The sunsynk 8kw is designed to sustain loads up to 90A provided that the grid or suitable generator is connected on the grid input. 

[Leshen]

Just now, Peter Topp said:

Hi I understand that however a inverter is also for load shedding and cannot sustain 90A loads as suggested.

Nowhere in the manual does it suggest that it will deliver 90A on the load port when Eskom isn’t available. 
 

That would make it a 21000w inverter. 

[Leshen]

20 minutes ago, Peter Topp said:

Hi I understand that however a inverter is also for load shedding and cannot sustain 90A loads as suggested.

Note that all inverters have a VA/W rating, Sunsynk, Victron, SMA, Fronius etc, meaning that a 10000VA/8000W Victron Quattro or an 8000W Sunsynk can only convert DC to AC at a max of 8000W. The rest has to be drawn from the grid.