Brown out and solar

[mopowr steve]

A customer of mine calls me with a question. Says he had a heat pump that both the compressor and fan motor burned up. Now this was noticed after the night before there was a power outage due to vehicle vs pole that took out that whole end of town.

I responded that I could have been caused by a brown-out vs a total outage, unfortunatly he was not there that night to verify what he experienced. Then I remembered that he has a solar system without battery storage. So my question is, what do solar systems do when there is low voltage (such as in a brown out) yet still see 60Hz. Do you think that this could contribute to further problems.

I haven’t been there to verify but just as I’m typing this it dawns on me that if I was there to check things out I think I would start by just checking the capacitor at condenser unit first.

 

[ggunn]

A customer of mine calls me with a question. Says he had a heat pump that both the compressor and fan motor burned up. Now this was noticed after the night before there was a power outage due to vehicle vs pole that took out that whole end of town.

I responded that I could have been caused by a brown-out vs a total outage, unfortunately he was not there that night to verify what he experienced. Then I remembered that he has a solar system without battery storage. So my question is, what do solar systems do when there is low voltage (such as in a brown out) yet still see 60Hz. Do you think that this could contribute to further problems.

I haven’t been there to verify but just as I’m typing this it dawns on me that if I was there to check things out I think I would start by just checking the capacitor at condenser unit first.

Grid tied PV works within a voltage window and matches voltage with what it sees from the grid. If the grid voltage moves out of the window or goes dark, the inverter shuts down.

 

[drcampbell]

It's possible the fan motor stopped turning a long time ago. When that happens, the compression ratio becomes abnormally high, putting abnormal stress on the compressor motor, possibly leading to failure. It's also possible that an overload relay turns them both off when either one overloads.

Vehicle vs. pole events don't usually lead to brownouts or motor burnouts, let alone simultaneous double burnouts. I almost hate to ask, but has power been restored to the house?

It's likely that the heat pump failure is completely unrelated to the presence of the solar panels or the V-P event. Seek the simplest answer first.

 

[sameguy]

"noticed after the night before there was a power outage" how far from the crash site is the house- too far for a fault to hit only him?
Crash at night solar would be "off".
My guess untimely death of the hvac equipment, unless it's old.

 

[Jraef]

Grid tied PV works within a voltage window and matches voltage with what it sees from the grid. If the grid voltage moves out of the window or goes dark, the inverter shuts down.

That's right. When there is no battery system involved, that defines it as a "grid tied" system and in order to have that, the inverter is specially designed as a "line interactive" system. That means it is monitoring the grid voltage and as soon as the line voltage drops, the inverter shuts down because it has to protect against back feeding the grid and killing a utility line worker. So the brown-out event and subsequent damage to the other equipment was unrelated.