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Sizing PV Surge Protector

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I have a Sunsynk 5.5kw Inverter with 6 x JA Solar 545 Panels in series with

Total Open Circuit Voltage(Voc) [V] = 298.5

Total Maximum Power Voltage(Vmp)[V] = 250

I have installed a 275V Surge Protector, by sizing for Voc and max inverter voltage (500V). Should I have sized for Vmp instead?  Is a 500V Surge Protector more suitable?

Assumed that it should would never go above the the Maximum Power Voltage, but it does around midday and I think it is being cut by the Surge Protector.

 

Screenshot from 2023-07-31 17-55-17.png

1 hour ago, MPAD said:

I have a Sunsynk 5.5kw Inverter with 6 x JA Solar 545 Panels in series with

Total Open Circuit Voltage(Voc) [V] = 298.5

Total Maximum Power Voltage(Vmp)[V] = 250

I have installed a 275V Surge Protector, by sizing for Voc and max inverter voltage (500V). Should I have sized for Vmp instead?  Is a 500V Surge Protector more suitable?

Assumed that it should would never go above the the Maximum Power Voltage, but it does around midday and I think it is being cut by the Surge Protector.

 

Screenshot from 2023-07-31 17-55-17.png

In cold weather like today yes the VOC can go up to 321v @ 0°C. Spec it for 500v otherwise you interfere with the mpp of the controller.

  • Author
9 minutes ago, TaliaB said:

In cold weather like today yes the VOC can go up to 321v @ 0°C. Spec it for 500v otherwise you interfere with the mpp of the controller.

I have found Surge devices online for 400V and 450V.  Is the 400V a better fit?  Or should I stick with 500V.  Concerned that the 500V might be too close to max inverter voltage to protect the inverter from surge.  

Edited by MPAD
Clarified comment

  • Author
2 minutes ago, JacquesVDM said:

The value of 275V lets me think it is a AC type for the 230v AC supply. Is it DC rated? I could be wrong. I would go with a 500V one as the inverter is designed for 500V.

It's DC

Screenshot from 2023-07-31 20-30-16.png

3 hours ago, TaliaB said:

In cold weather like today yes the VOC can go up to 321v @ 0°C. Spec it for 500v otherwise you interfere with the mpp of the controller.

Based on the below specs for the 5kW is it not better to spec it for 450V instead of 500V?

I’m not quite sure what happens between 425V and 500V? Does the MPPT stop producing any power? Do you happen to know?

IMG_5618.thumb.jpeg.e5206c15328378e0578d204fc0539aab.jpeg

 

Surge protectors are mainly for lightening. A lightning strike nearby will be way over 500V. 400 or 500V surge protector will be fine. 

Surge protectors won't clip the voltage. They will blow with a short circuit to earth. The green indicator on the front will go red. 

2 hours ago, Chris_S said:

Surge protectors are mainly for lightening. A lightning strike nearby will be way over 500V. 400 or 500V surge protector will be fine. 

Surge protectors won't clip the voltage. They will blow with a short circuit to earth. The green indicator on the front will go red. 

I'm afraid the above is incorrect. The SP devices have several protection circuits inside, which operate at different situations. The devices can activate and clip the voltage multiple times and still work fine afterwards. They are not a simple fuse device which blows off ones and turn red. Do your research. There are many sources on the net which explain their operation in detail.

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