rthorntn wrote: ↑Tue, 22 Dec 2020, 13:09
is there an area in the inverter that can be troublesome and may cause this kind of thing that I can pay particular attention to?
Well, the three things that the manufacturer put heat sensors might be a good place to start:
* Heatksink for the low voltage end of the DC-DC converter (the 16 MOSFETs)
* Heatsink for the inverter proper (the DC-AC converter, 4 IGBTs), high voltage end of the DC-DC converter (4 more IGBTs), and the buck converter (one IGBT and a diode). If suspicious of this area (higher difference with the other inverter), it might be worth determining which end gets hottest (the DC-AC end or the DC-DC end)
* The high frequency transformer.
On other models, there is another heat sensor on the solar charge controller. But on models like yours, the solar charge controller is a boost converter, and I suspect it lives on the same heatsink as the IGBTs. It has its own inductor, tucked into a corner with its own small PCB on top. This inductor may be failing with temperature, or it may be sending heat to other parts of the circuit.
Knowing that the heat had trapped in these two inverters for some time, it's possible that some of the capacitors have suffered reduced lifespan. I'd consider replacing the bus capacitors and the 4 capacitors protecting the low voltage side of the DC-DC converter (i.e. protecting the 16 MOSFETs). Though usually if these fail, the MOSFETs short out with a loud bang. I wonder if some capacitors in the power supply might have failed or be near the end of their useful life. It would be worth searching for electrolytic capacitors with distorted cans, like these three:
There must be a dozens of electrolytic capacitors, some quite small, that could cause problems. But I'd suspect the main power supply
for your symptoms.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.