Double the lifetime of an inverter?

[J.P.M.]

I guess the luck takes big place of inverter life. I keep mine in air conditioned garage/storage and I'm on my 3rd SMA 6000TL-US-12 in 2.5 yrs. The 2 failures has to do with design/human error besides the inverter itself. More simple it gets, longer life it has.

Something doesn't sound quite right there. If another failure happens in 1+ yrs. or so, I'd look beyond inverter quality. SMA stuff seems pretty robust with a good reputation for quality.

[silversaver]

I guess the luck takes big place of inverter life. I keep mine in air conditioned garage/storage and I'm on my 3rd SMA 6000TL-US-12 in 2.5 yrs. The 2 failures has to do with design/human error besides the inverter itself. More simple it gets, longer life it has.

[ButchDeal]

Totally agree that cooling should be considered, and that the chances it helps probably outweighs the chances it hurts (vibration, fouling, etc). I think any suggestion that inverter life will double with the addition of a muffin fan is ridiculous.

I wouldn't rule out outdoor installations... better natural airflow could actually result in lower temps relative to inside. Also keep in mind that IGBT failures are up there with caps and fets in the possible failure modes.

I would deffinitly consider outside for fan less outdoor rated inverters. If the higher power units have fans then consider attempting to retrofit the higher power units fan.

The main concern with this hypothesis is the assumption that " it can't hurt". I would say that as suggested ( high speed unregulated fan) it deffinitly can hurt.
Just take a look inside an old server that has been on steady for two plus years. The amount of dust and surface dirt stuck to the heat sources inside is great. A few mm of dirt is very insulating greatly increasing the heat build up on the parts that specifically need to be cooled. Heat syncs are like filters and. Clog first wi any forced air.
Units designed for convection cooling have larger heat syncs that are generally more convoluted allowing more surface area to dissipate heat more easily in the slow moving air. This larger surface area is going to clog quickly with dirt.
The units that have fans have thermal couplers and variable speed fans to cut down on the dirt build up as much as possible and heat syncs designed to trap less. What is important for the curves as dis used is the temerature of the components so insolation is unwanted.
I would suggest that if you attempt this forced air retrofit that you use a thermal coupler, variable speed fan, and annual shut down with cleaning. Of course the cleaning could result in higher failure rates as well particularly if performed by untrained personal, but better than trying to go decades with out.

[J.P.M.]

A comment or 2:

1.) While it seems that heat is probably better removed from electronic devices than not, the benefits in terms of improved service life and lower service requirements seem at best not well or easily quantified. I'm not sure a process cost analysis is worth it for the cost of ~~ $20/yr. of electricity spent to extend (??) an inverter life by an unknown and probably unknowable number of years.

2.) Depending on the cooling scheme used - from a window fan under the inverter in a garage blowing up, to mounted outside w/ access to a breeze, to a sophisticated cooling system, for the cheap methods, the cost of power for aux. cooling ranges from zero (mounted outdoor) to the cost of a window fan and 40W of power, to whatever for more sophisticated methods. If the cost is from zero to cheap, cooling may not hurt provided done in a common sense and safe manner. The PITA/noise factor will probably trump. the power/equipment cost.

3.) Two things to perhaps consider with cheap, open system cooling (e.g., window fans): The additional air blowing past any cooling fins will probably cause the fins to foul w/dust/crud/etc. and work less efficiently, increasing the inverter temp. in a general way, and somewhat working against the goal of lower inverter temps. A lot of times, access to the cooling system is difficult/impossible. Also, depending on how and mostly when the aux. cooling is introduced, there is the situation of thermal cyclic stress put on components from differential thermal expansion. An already hot inverter that gets relatively abrupt forced cooling air cooling introduced will have some higher risk of problems than one that has the cooling already present before heating. Often, a strong contributing factor to equipment failures is not entirely one of elevated temps., but also up/down temp. cycling, and is somewhat a separate issue from the failures caused by continuous heat (component cooking) in and of itself.

ADD:

4.) As for elevated temps. of an enclosed space, A 5kW system under full load will probably add about a 150 W load to the space. If an uninsulated garage, the interior temp. will increase in proportion to the added load divided by the enclosed space heat loss rate. Bottom line for my uninsulated garage case, that adds about 2 deg. F. to the garage temp., +/- a degree or 2. Just sayin.

[halayman]

high temperatures are the worst enemy to the lifespan of inverters, here in Egypt even the best quality solar inverters hardly last for more than 2 years due to high temperatures

[DaveDE2]

Those big blue electrolytic caps are indeed part of the inversion circuit. The logic circuits would have no need for such large caps. Also, optimizers still have plenty of capacitors, just not electrolytics. They're ceramic caps which will last a lot longer.

Those little brown rectangles near the bottom of the board in the photo are the buck-boost conversion caps:

http://www.interpv.net/tech/tech_view.asp?idx=564&part_code=010050014

[jflorey2]

Totally agree that cooling should be considered, and that the chances it helps probably outweighs the chances it hurts (vibration, fouling, etc). I think any suggestion that inverter life will double with the addition of a muffin fan is ridiculous.

Definitely. Heat is only one of the many factors in determining longevity of any electronic device.

I wouldn't rule out outdoor installations... better natural airflow could actually result in lower temps relative to inside.

And in cases where it the inverter is mounted inside an unvented garage, average temperatures could well be higher.

[ButchDeal]

That is the logic circuit not the main power circuit. The optimizers don't have any caps. Many inverters have caps in the low power circuits that monitor the inverter.

[sensij]

Sooner or later, either the caps or fets will hit that and thus failure. So the idea of cooling the inverter in an indoor environment should be considered imo.

Totally agree that cooling should be considered, and that the chances it helps probably outweighs the chances it hurts (vibration, fouling, etc). I think any suggestion that inverter life will double with the addition of a muffin fan is ridiculous.

I wouldn't rule out outdoor installations... better natural airflow could actually result in lower temps relative to inside. Also keep in mind that IGBT failures are up there with caps and fets in the possible failure modes.

[DaveDE2]

Now then, for everybody who is still on board here, we have established that the main killer of an inverter longevity is heat. The most prevalent failures are Capacitors and Mosfets because they do the heavy lifting in the inversion process and run hottest. This statement is backed up by an SMA tech repairman I talked to here in Denver and makes total sense to me. There will always be one-off failures of other components but they are relatively rare.

If you want to read about capacitor and semiconductor lifetime vs heat, this is a good place to start:

http://www.illinoiscapacitor.com/tec...lculators.aspx

http://www.semicon.panasonic.co.jp/en/aboutus/pdf/t04007be-3.pdf

It's obvious why the fanless inverters come that way because the MFGs produce these by the hundreds of thousands and a lot of them will be installed in outdoor environments. Having a fan outside would cause all sorts of failures (in the fan) and so they avoid it at all cost. Furthermore, the mfgs are all in competition and need to keep cost low. As such, imo, they just want their inverters to outlive the warranty. If an inverter is installed indoors in a relatively benign environment then it has a greater chance of living longer. The assumption here is that what causes an inverter to die of old age is the ramping effect at the end of the bathtub curve. Sooner or later, either the caps or fets will hit that and thus failure. So the idea of cooling the inverter in an indoor environment should be considered imo.

[azdave]

Nope. No fan upgrades to my flat-6 Corvairs (at least those with stock engines). I seriously upgraded the fans in my 455 big block Corvair though.

[DaveDE2]

Well here's a product that still has them (as do my new SMA inverters and probably every other inverter ever made)

http://www.solarprof.nl/2-uncategorised

[bcroe]

Huh? The inverter obviously spends only a small part of the day operating at peak temperature. Where does the 10 years estimate come from?

Yes and no. My inverters might run in clipping for 8 hours straight. At least they are indoors. Bruce Roe

[J.P.M.]

We're all shootin' from hip here anyway.

How about half of us put extra cooling on our inverters and the other half leave them as is. Then we'll all check back on this thread in 20 years and see who was right.

Probably a practical observation. Failure rates/MTBF's, etc. are tough to quantify/estimate for this stuff anyway.

[jflorey2]

Gosh, you are so totally wrong. I've been in the aerospace business for 30 years

Well, let's all hope you haven't gotten your hands on anything critical, then.