RegGuheert said:
FWIW, the following may be purely coincidental, but one thing that is interesting about the failed inverter is that it had previously outperformed ALL of the other 41 inverters in the array over the life of the system.
Based on this little factoid, I am going to make the following predictions:
- The next inverter to fail in our PV array will be 121045414066. This inverter is in the garage array, top row, second from the left.
- The second inverter to fail in the future in our PV array will be 121045415714. This inverter is in the house array, middle row, third from the left.
- The third inverter to fail in the future in our PV array will be 121045414823. This inverter is in the garage array, top row, fifth from the left.
- The fourth inverter to fail in the future in our PV array will be 121045415782. This inverter is in the house array, bottom row, second from the left.
So, on what do I make these predictions? Just a hypothesis that the previous failure was brought on first because of higher stress on the components due to consistently operating at a higher power level than the other inverters. I cannot tell whether this operation at higher power levels is due to being connected to a more powerful PV module or due to some variation within the inverters which causes them to operate at higher power levels than their neighbors or some combination of the two things. But I do not think it should matter: higher power levels should mean more stress and a shorter life.
This is not an overly-important prediction, but I wanted to record it as a way to see if any predictions can be made about which M190s are at the highest risk of early failure.
On a related note, I am wondering if PV module power level is important in determining which systems are likely to experience the most failures. As I have said previously, temperature does not seem to be the primary determining factor in these M190 failures. But perhaps PV module power impacts the magnitude of thermal cycling that happens each day and therefore the stresses on the solder joints.
For reference, the PV modules in our PV system on the roof are 235Wp. The PV modules in the field array are pairs of 120Wp modules, so 240Wp total, but with 72 cells, so the voltage stresses are higher and the current stresses are lower than the 235Wp modules on the roof.