Why would the Main breaker trip?

[EPadayhag]

I recently installed a photovoltaic solar system for a customer but there seems to be a problem with on of the breakers.
Here is a bit of context: The panelboard is a 100A main/125A bus 3ph 480V. The sum of the breakers is 120A (30,30,30,15,15) and each breaker is connected to an inverter.

What happened was when we installed the most recent 15A inverter, the breaker almost immediately tripped and the inverter was virtually destroyed. We quickly found that the inverter was actually a 208V, not 480V... We then replaced it with the correct inverter and reset the breaker. This worked fine and the system ran smoothly for about 4 months. But just a few days ago the breaker again tripped but this time tripped the main breaker along with it, and again damaging the inverter. Now we are stuck thinking why this happened.

Right now we have a few ideas but are not quite sure:
Is the sum of all the breakers too high for the panel to handle?
Or maybe the breaker was damaged and weakened the first time and finally completely failed the second time?

 

[Pete999]

I recently installed a photovoltaic solar system for a customer but there seems to be a problem with on of the breakers.
Here is a bit of context: The panelboard is a 100A main/125A bus 3ph 480V. The sum of the breakers is 120A (30,30,30,15,15) and each breaker is connected to an inverter.

What happened was when we installed the most recent 15A inverter, the breaker almost immediately tripped and the inverter was virtually destroyed. We quickly found that the inverter was actually a 208V, not 480V... We then replaced it with the correct inverter and reset the breaker. This worked fine and the system ran smoothly for about 4 months. But just a few days ago the breaker again tripped but this time tripped the main breaker along with it, and again damaging the inverter. Now we are stuck thinking why this happened.

Right now we have a few ideas but are not quite sure:
Is the sum of all the breakers too high for the panel to handle?
Or maybe the breaker was damaged and weakened the first time and finally completely failed the second time?

What solar experience or, qualifications do you currently posses Epaday?

 

[EPadayhag]

What solar experience or, qualifications do you currently posses Epaday?

I have been a solar system designer for nearly 3 years, this is one of our larger 3ph projects. Unfortunately our head electrician left the company since the initial install of this project.

 

[jackhammerJIM]

Can you post some pictures of the main panel \ submain setup or you can pay for Petes flights he will happily take a look for you

 

[Megawatt]

I recently installed a photovoltaic solar system for a customer but there seems to be a problem with on of the breakers.
Here is a bit of context: The panelboard is a 100A main/125A bus 3ph 480V. The sum of the breakers is 120A (30,30,30,15,15) and each breaker is connected to an inverter.

What happened was when we installed the most recent 15A inverter, the breaker almost immediately tripped and the inverter was virtually destroyed. We quickly found that the inverter was actually a 208V, not 480V... We then replaced it with the correct inverter and reset the breaker. This worked fine and the system ran smoothly for about 4 months. But just a few days ago the breaker again tripped but this time tripped the main breaker along with it, and again damaging the inverter. Now we are stuck thinking why this happened.

Right now we have a few ideas but are not quite sure:
Is the sum of all the breakers too high for the panel to handle?
Or maybe the breaker was damaged and weakened the first time and finally completely failed the second time?

Ep I have seen breakers that won’t trip even it went phase to phase so yes that’s possible. When it comes to sizing breakers and you look in the panel and start adding the sum of all the breakers exceed the main breaker is because what you have what is called a calculated load ( breakers ) and then you have connected loads on an average day your panel is probably pulling 30 amps because all the breakers are not pulling current at the same time. As with the problem that’s causing the inverter to fry and I’m assuming it’s the same one something just isn’t wired right. I don’t know enough about solar work to advise you but we have a solar power forum. They should be able to help you sorry

 

[davesparks]

It's far more likely that a fault occurred in the inverter which caused an overcurrent which tripped the breakers, not a tripping breaker causing the inverter to develop a fault.

It is likely that both breakers operated due to a lack of selectivity/discrimination.