Hi Guys/Gals

So I've decided to take the plunge and invest in a solar installation and as the title above states, I'm worried I may mess it up.

 

I've received a quote for the following Grid Tied Hybrid System with no grid feed :

• Sunsynk 5kW Hybrid PV inverter
• 10 Mono 450W panels
• 2 PYLONTECH US3000C 3.5kW batteries
• All the goodies to get it connected and legal.

I'm a bit careful buyer and always do a lot of research before actually pulling the trigger with almost everything these days.

After reading a webinar I found online I have a small concern with the setup above. The US3000C batteries are rated at 37A recommended discharge rate but the SunSynk is rated at 120A DC input. I know the inverter isn't going to be drawing that current all the time but in the event of a load kicking on during the evening when batteries are discharging can the US3000C sustain the 60A each and would this decrease the amount of cycles it is rated at? 

37A X 2 Batteries X 48V = 3552W Recommended Current and not the 5500W the unit is rated at.

I would rather ask these questions here and spend the money to do it right the first time.

 

Any feedback here would really be appreciated.

I love the Hubble units. Able to discharge at 100A if I am correct. I need to stay neutral as admin, however I hope this is helpful.

Jay

58 minutes ago, AMH said:

Hi Guys/Gals

So I've decided to take the plunge and invest in a solar installation and as the title above states, I'm worried I may mess it up.

 

I've received a quote for the following Grid Tied Hybrid System with no grid feed :

• Sunsynk 5kW Hybrid PV inverter
• 10 Mono 450W panels
• 2 PYLONTECH US3000C 3.5kW batteries
• All the goodies to get it connected and legal.

I'm a bit careful buyer and always do a lot of research before actually pulling the trigger with almost everything these days.

After reading a webinar I found online I have a small concern with the setup above. The US3000C batteries are rated at 37A recommended discharge rate but the SunSynk is rated at 120A DC input. I know the inverter isn't going to be drawing that current all the time but in the event of a load kicking on during the evening when batteries are discharging can the US3000C sustain the 60A each and would this decrease the amount of cycles it is rated at? 

37A X 2 Batteries X 48V = 3552W Recommended Current and not the 5500W the unit is rated at.

I would rather ask these questions here and spend the money to do it right the first time.

 

Any feedback here would really be appreciated.

I have 4 us3000 batteries but started off with 3 us3000b batteries and the max discharge rate can be an issue. Fortunately I only had the BMS switch off the batteries twice during loadshedding. With 4 I no longer have to worry about the Max discharge rates. 

If I had to start over I would go with the hubble Am2 5.5kw. Even one of these to start with would be better than 2 us3000c batteries. 

I have had a look at the Hubble AM2 and it does look good.

The AM2 is rated at a maximum discharge rate of 100A which is a bit better than the Pylontech but once again, the maximum.

Does anyone have a technical brochure for the AM2 with the recommended discharge rate?

 

Hi AMH

You can download the AM2 manuals from the Hubble website.

https://www.hubblelithium.co.za/products.html

Edited April 15, 20215 yr by Peter Topp

As above, definitively consider the Hubble. However, I do believe one can limit the max battery draw on that inverter so that shouldn't be an issue. 

10 hours ago, AMH said:

Hi Guys/Gals

So I've decided to take the plunge and invest in a solar installation and as the title above states, I'm worried I may mess it up.

 

I've received a quote for the following Grid Tied Hybrid System with no grid feed :

• Sunsynk 5kW Hybrid PV inverter
• 10 Mono 450W panels
• 2 PYLONTECH US3000C 3.5kW batteries
• All the goodies to get it connected and legal.

I'm a bit careful buyer and always do a lot of research before actually pulling the trigger with almost everything these days.

After reading a webinar I found online I have a small concern with the setup above. The US3000C batteries are rated at 37A recommended discharge rate but the SunSynk is rated at 120A DC input. I know the inverter isn't going to be drawing that current all the time but in the event of a load kicking on during the evening when batteries are discharging can the US3000C sustain the 60A each and would this decrease the amount of cycles it is rated at? 

37A X 2 Batteries X 48V = 3552W Recommended Current and not the 5500W the unit is rated at.

I would rather ask these questions here and spend the money to do it right the first time.

 

Any feedback here would really be appreciated.

You would only be able to squeeze about 3500 watts max out of the inverter with the above. To get the full 5K out of the inverter, you can add another US3000 (for 3 in total), or go for the Hubble. At the current Powerforumstore price, I'd go for two Hubbles. Edit: Or you could consider the BSLBatt, also a 1C battery.

Edited April 16, 20215 yr by YellowTapemeasure

9 hours ago, AMH said:

I have had a look at the Hubble AM2 and it does look good.

The AM2 is rated at a maximum discharge rate of 100A which is a bit better than the Pylontech but once again, the maximum.

Does anyone have a technical brochure for the AM2 with the recommended discharge rate?

 

Actually even slightly more, 5.5K @ 51V is 107 A (1 Coulomb).

1 hour ago, YellowTapemeasure said:

Actually even slightly more, 5.5K @ 51V is 107 A (1 Coulomb).

 

25 minutes ago, Energy-Jason said:

 

Is that from a single Hubble?

14 minutes ago, YellowTapemeasure said:

Is that from a single Hubble?

Yes sir! Was doing a full cycle and put all the essential loads on I had. Was vacuuming and making coffee . Hahah.

13 minutes ago, Energy-Jason said:

Yes sir! Was doing a full cycle and put all the essential loads on I had. Was vacuuming and making coffee . Hahah.

😁

Have you noticed that coffee made from alternative power always tastes sweeter somehow?

Very much so!! What a great kit. 

Sincerely

Jason

So....

I have decided to go with 2 X Hubble AM-2 batteries for my installation.

Thanks for all the input.

Next question though...

The Sunsynk has a maximum PV Input Voltage of 500V with a MPPT range of 125~425V

I am going to be installing 10 X 450W panels and am not sure if I need to split the array into 2 X 5 or keep it all on a single string of 1 X 10 ?

The 10 panels I have are LONGi Solar LR4-72HIH-450M which are rated at 49.3Voc/V at their  standard testing conditions but 46.2Voc/V at normal operating conditions. ( I have attached the technical information for the panels )

Any feedback or advise would really be appreciated.

Longi LR4-72HIH-440M_Datasheet_EN.pdf

The most NB question we need to ask you  is who is going to install the solution for you?

They will work out how many strings etc are optional taking into account your roof space and direction.

Here is a good summary of what how he will arrive at the optimum solution for you..(I copied it from somewhere, no reference unfortunately).

 

VOc as a function of Temp.

As temp decreases, V increases. We want to calculate the maximum Voc for a panel at the minimum temp we expect in the region. So for JHB we use 0’C, in Bloemfontein we use -10C.

To calculate string length (series) use the total Voc (including adjustment for cold temp) from panel data sheet and then do as follows;

 

Record-low temperature: -10ºC (From your region, town)
Temperature coefficient of (VOC): – (0.30) %/ºC (From data sheet *)
Module open circuit voltage (VOC): 39.4 V *
Inverter maximum input voltage: 600V (From inverter, MPPT data sheet)

The STC temperature is 25ºC. This temperature needs to be deducted from the array location’s record-low temperature of -10 degrees as follows:

25 – (-10) = 35º difference.

Multiply the 35º difference by the temperature coefficient of VOC (I’ve used the positive value for an easier calculation, though you get the same result) then multiply by the module’s VOC:

35 x 0.0030 = 0.105
0.105 x 39.4V = 4.137V (So the Voc will increase by 4.13 V if the temp goes down to -10C)

This is how many volts each module will increase due to record-low temperatures. Add the voltage increase to the Module VOC. Then divide the inverter maximum input voltage by that number. This will give you the maximum number of modules that can be wired in a series string per that inverter and specific location.

4.137 V + 39.4V = 43.537 Vmax (At -10C) Increase in voltage due to temp drop per panel. Normal voltage at 25C
600V / 43.537 = 13.7 (round down to a whole number)

The maximum number of modules in this series string is 13. A series string of 14 could potentially produce more than 600V during record-low temperatures.

 

When string in parallel, add Current, V stays the same, when in series, add Voltage, I stays the same.

 

 

25 minutes ago, FixAMess said:

The most NB question we need to ask you  is who is going to install the solution for you?

They will work out how many strings etc are optional taking into account your roof space and direction.

Here is a good summary of what how he will arrive at the optimum solution for you..(I copied it from somewhere, no reference unfortunately).

 

VOc as a function of Temp.

As temp decreases, V increases. We want to calculate the maximum Voc for a panel at the minimum temp we expect in the region. So for JHB we use 0’C, in Bloemfontein we use -10C.

To calculate string length (series) use the total Voc (including adjustment for cold temp) from panel data sheet and then do as follows;

 

Record-low temperature: -10ºC (From your region, town)
Temperature coefficient of (VOC): – (0.30) %/ºC (From data sheet *)
Module open circuit voltage (VOC): 39.4 V *
Inverter maximum input voltage: 600V (From inverter, MPPT data sheet)

The STC temperature is 25ºC. This temperature needs to be deducted from the array location’s record-low temperature of -10 degrees as follows:

25 – (-10) = 35º difference.

Multiply the 35º difference by the temperature coefficient of VOC (I’ve used the positive value for an easier calculation, though you get the same result) then multiply by the module’s VOC:

35 x 0.0030 = 0.105
0.105 x 39.4V = 4.137V (So the Voc will increase by 4.13 V if the temp goes down to -10C)

This is how many volts each module will increase due to record-low temperatures. Add the voltage increase to the Module VOC. Then divide the inverter maximum input voltage by that number. This will give you the maximum number of modules that can be wired in a series string per that inverter and specific location.

4.137 V + 39.4V = 43.537 Vmax (At -10C) Increase in voltage due to temp drop per panel. Normal voltage at 25C
600V / 43.537 = 13.7 (round down to a whole number)

The maximum number of modules in this series string is 13. A series string of 14 could potentially produce more than 600V during record-low temperatures.

 

When string in parallel, add Current, V stays the same, when in series, add Voltage, I stays the same.

 

 

I do have a company that will be doing the installation for me. I just like to know my options and what works best and why.

The maths dictates that I will only be able to have 9 panels per string to stay below the Sunsynk max PV Input Voltage of 500V

Would it be more efficient to split the 10 panel string onto the 2 MPPT's or keep a single string of 9 panles?

3 minutes ago, AMH said:

split the 10 panel string onto the 2 MPPT's

that would be my suggestion...

52 minutes ago, AMH said:

I do have a company that will be doing the installation for me. I just like to know my options and what works best and why.

The maths dictates that I will only be able to have 9 panels per string to stay below the Sunsynk max PV Input Voltage of 500V

Would it be more efficient to split the 10 panel string onto the 2 MPPT's or keep a single string of 9 panles?

As per Keith Gough, you will need to keep each string at under 450V, so that means a max of 9, but then you still need to compensate for temperature drop as @FixAMesshas pointed out. You will need to do the sums and make a call on the risk of blowing your MPPT on a cold winter's morning. 265V (5 in series) is more than adequate to start the MPPT, On my 5.5K Sunsynk I originally used 2 strings of 6x 3380W JA Solars, and it performed very well, Another good reason for using two strings would be if you had any shading on your panels from, say, a nearby tree. Splitting the panels into two strings may mean that only one may get affected by shade.

45 minutes ago, YellowTapemeasure said:

As per Keith Gough, you will need to keep each string at under 450V, so that means a max of 9, but then you still need to compensate for temperature drop as @FixAMesshas pointed out. You will need to do the sums and make a call on the risk of blowing your MPPT on a cold winter's morning. 265V (5 in series) is more than adequate to start the MPPT, On my 5.5K Sunsynk I originally used 2 strings of 6x 3380W JA Solars, and it performed very well, Another good reason for using two strings would be if you had any shading on your panels from, say, a nearby tree. Splitting the panels into two strings may mean that only one may get affected by shade.

I did the maths and believe the best option would be to split the array as per @Kalahari Meerkat

My main concern is/was the start voltage for the MPPT on overcast days. I suppose I could always add to each array as required in the future.

 

19 hours ago, AMH said:

I did the maths and believe the best option would be to split the array as per @Kalahari Meerkat

My main concern is/was the start voltage for the MPPT on overcast days. I suppose I could always add to each array as required in the future.

 

Completely understandable.

Just to correct my post,

Quote

2 strings of 6x 3380W JA Solars

was meant to be

2 strings of 6x 380W JA Solars.

I have subsequently added 4 panels, so I now have 2 strings of 8x 380W JA Solars. To give you an idea of MPPT statup on bad solar days, this morning in Gauteng it was raining and very overcast, the arrays started producing its first Watts at 07H13, so it's not all that bad.