Wiring Help - Panels

[Riaan]

Hi Guys,
Please have a look at my proposed wiring diagram attached. Would this be suitable against the specs mentioned below?

Here are the specs for the Inverter and Solar Panel. I Need to connect 12 Panels.

5Kva Inverter

Inverter Mode:
Rated Power: 5000VA/5000W
DC Input: 48VDC, 117A
AC Output: 230VAC, 50/60Hz, 22A

AC Charger Mode:
AC Input: 230VAC, 50/60Hz, 35A
DC Output: 54VDC
Max. 60A, Default 30A

Solar Charge Mode:
Rated Current: 80A
System Voltage: 48VDC
Min Solar Voltage: 40VDC
Max Solar Voltage: (VOC): 145VDC

_________________________________________________

Panel Details:

Nominal Maximum Power: (Pmax): 365 W
Optimum Operating Voltage (Vmp): 39.8 V
Optimum Operating Current (Imp): 9.18 A
Open Circuit Voltage (Voc): 47.2 V
Short Circuit Current (Isc): 9.75 A

Maximum Series Fuse Rating: 30 A

Reply
Report

 

[rmaddy]

Assuming a 48V nominal system.

3 of those panels in series will produce 141.6V @ 25ºC. Voc goes up as temperature goes down. They will produce over 150V near 0ºC. Your SCC supports a max of 145V. That's not going to work. You need a charge controller that support more voltage unless you can guarantee your panels will never ever be exposed to temperatures below about 20ºC.

4 of those panels in parallel can result in nearly 98A outgoing to the battery. But the SCC will limit it to 80A. You need a charge controller that supports more current if you want to take advantage of what the panels can produce.

In other words, wiring 12 panels as 3S4P with a 145/80 SCC isn't going to work.

An alternate plan would be to have two sets of 2S3P each with their own 145/50 SCC. At 2S3P you would have close to 105V and almost 50A near 0ºC.

On your diagram you have the following:

1 When connecting solar panels in series, we get an increased wattage in combination with a higher voltage

While technically true it should read more like the line below it about connecting in parallel:

1 When connecting solar panels in series the amperage stays the same but the voltage goes up.

Whether wired in series or parallel you get the same wattage which is simply the number of panels times the watts of each panel.

Also on your diagram you show Total Volts of 105V. Where did you get that number from? That would be true of panels with a Voc of 35V wired as 3S @ 25ºC. Your panels are 47.2V Voc.

 

[Riaan]

Assuming a 48V nominal system.

3 of those panels in series will produce 141.6V @ 25ºC. Voc goes up as temperature goes down. They will produce over 150V near 0ºC. Your SCC supports a max of 145V. That's not going to work. You need a charge controller that support more voltage unless you can guarantee your panels will never ever be exposed to temperatures below about 20ºC.

4 of those panels in parallel can result in nearly 98A outgoing to the battery. But the SCC will limit it to 80A. You need a charge controller that supports more current if you want to take advantage of what the panels can produce.

In other words, wiring 12 panels as 3S4P with a 145/80 SCC isn't going to work.

An alternate plan would be to have two sets of 2S3P each with their own 145/50 SCC. At 2S3P you would have close to 105V and almost 50A near 0ºC.

On your diagram you have the following:

1 When connecting solar panels in series, we get an increased wattage in combination with a higher voltage

While technically true it should read more like the line below it about connecting in parallel:

1 When connecting solar panels in series the amperage stays the same but the voltage goes up.

Whether wired in series or parallel you get the same wattage which is simply the number of panels times the watts of each panel.

Also on your diagram you show Total Volts of 105V. Where did you get that number from? That would be true of panels with a Voc of 35V wired as 3S @ 25ºC. Your panels are 47.2V Voc.

Hi Maddy,

Thank you very much. It makes more sense now. I Did not at all took the temperature in consideration. You are right, the 105V is a calculation error on my side.

Again, Thank you

 

[MichaelK]

BTW, it appears that the "Min Solar Voltage: 40VDC" is a typo? It's more likely to be 60V for a 48V system, and even 60V is bare, bare minimum. A 48V battery can NOT charge with an input of 40V. Minimal charging will start at about 50V, and max out at about 59-60V. A flooded battery would want to be equilized at ~64V.

However, with the proposed 2S wiring scheme, you'll be putting out 79.6V, which should be fine.