RegGuheert on April 2, 2014 wrote:More likely the failures in the M190s are due to a solder joint or component which is failing due to thermal cycling. (And I really don't think the electrolytic capacitors are the main culprits at this early stage in the game.)
On page 32 of the presentation Enphase made to stock analysts on June, 19, 2017,
they confirmed that the electrolytic capacitors are NOT involved in the top ten failure modes for their microinveters:
Enphase on page 32 of Analyst Day Presentation, June 19, 2017 wrote:Enphase has solved the e-cap problem
Enphase on page 32 of Analyst Day Presentation, June 19, 2017 wrote:- No degradation after 5 years of operation
- Not in the top 10 failure modes
- Lifetime failures:
-- 9 out of 56 million
-- 0.16 dppm per e-cap
- I find it interesting that they are bringing this up in the middle of 2017. My guess is that stock analysts have been hammering their stock and citing failures of their electrolytic capacitors as one of the reasons.
- I wonder why they didn't specify which products contain electrolytic capacitors. I believe that the M190s and the original M215s contain aluminum electrolytic capacitors and that all later microinverter products do not. But if it is true that they haven't built microinverters with electrolytic capacitors since 2014, why didn't they say so in this presentation?
- If the electrolytic capacitors are not in the top ten failure modes, then what problems ARE in the top 10? Isn't it important to help investors understand that the REAL problems have been understood and addressed in current products?
- The fact that electrolytic capacitors are not in the top ten failure modes for the Enphase microinverters helps to clarify why other manufacturers who don't use those capacitors have such dismal failure rates.
- The scatter plot of capacitance versus time shows results from two manufacturers: Nichicon and UCC. I have discussed Nichicon extensively in this thread, so I am familiar with their products, but I do not even know who UCC is. Does anyone know this company?
- Even if the random failure rate of the aluminum electrolytic capacitors is very low, as they indicated through their original analysis and as they are indicating to their investors in this presentation, the Nichicon aluminum electrolytics cannot be expected to have a lifetime longer than 15 years. Nichicon was very clear about this point in their datasheet for their product. I am quite sure this is why the M190s only have a 15-year warranty. And the switch to metal film capacitors would explain why they can provide a 25-year warranty on the M250s, M215IGs, and later inverters. But that still leaves the original M215s, which apparently share the new packaging and Engage support with the later models, but apparently use a power stage similar to the M190s, including the aluminum electrolytic capacitors. It will be interesting to see what happens after another 10 years in the field with these inverters relative to the M250s and M215IGs. Was Nichicon being overly pessimistic, or do these capacitors really give up the ghost after about 15 years?
In any case, Enphase has confirmed that competitors' marketing about the aluminum electrolytic capacitors is a bit of a red herring. They have also confirmed that there are other things which are driving the higher-than-specified failure rates in their products. The overall M190 population is experiencing approximately 10X as many failures as the datasheet touted and some installations have failure rates that are another 10X worse, or 100X worse than specified. Both the original M215 and the M250 microinverters are holding up well in the field so far and are currently giving MTBF numbers similar to those specified for the M190. (Enphase stopped putting that number on the datasheets after the M190.) But there is one exception: the M215s in GetOffYourGas' system are only giving him an MTBF of about 17 years, or about 20X worse than the original M190 specification of 331 years. We have not collected enough data for any other microinverters to establish a believable MTBF number.