For me the biggest problem with cheap Chinese products is actually the lack of reliable information and reviews on them rather than inferior quality. When it comes to "pure sine wave" inverters we all know they are traditionally very expensive. But lately the market seems to be flooded with Chinese TSW inverters with price tags that are truly pricing traditional MSW inverters out of the market.
I for one recently purchased a Ningbo Kosun 24v 2500w TSW inverter for less than $400!
But what about the potential problems that one may encounter with these "quote me happy" inverters?
They are so fresh on the market there is no independent feedback available on most of them.
IMO there are some advantages of going the cheap Chinese route, based on my experience with the Kosun TSW inverter:
* They could incorporate the latest high-performance technology (even though its cheap)
* They can be highly efficient due to the use of more solid state digital components and less analogue/mechanical components. Mine for example has no large transformer.
* Low upfront cost makes purchasing a higher capacity unit is possible giving more freedom to expand and/or lower percentage load on the unit = lower operating temperature.
Issues I have picked up with mine are as follows:
* Unstable AC ouput voltage when loads are under 400watts (16% load). The inverter's voltage regulating feedback loop does not switch smoothly under 16% load and creates sharp irregular amplitude pulses on the AC output. The amplitude pulses do however fall within the 10% AC regulation specification in the manual, but due to their frequency and irregularity it can be very annoying when using CFL or LED lighting as it causes them to flicker. The unstable feedback loop also causes high-current pulses on the DC side which register on the kilo-amper scale even when the average current is only in the single digits. You can actauly "feel" these high current pulses in the battery cables due to the magnetic inductance!
* At loads exceeding 16% the voltage regulating feedback loop stabilises and so does the AC output, however a small amount of high frequency noise is detectable in the AC power but is not an issue for concern.
Other than these issues I have no other complaints and would recommend this inverter for anyone who needs a TSW inverter on a very tight budget!
The only thing that remains to be seen is the long term reliability of the unit. It comes with an 18 month factory workmanship and material defects warranty. Mine has been going pretty much 24/7 for the last 4 months. I would however tend to feel that the unstable feedback loop at <16% loads may be putting additional strain on the components although having no experience in this particular field I cannot say that for sure. As such I try to run >16% loads wherever I can.
If anyone else has experience they would like to share on budget Chinese inverters please post here!
Regards,Sorry for replying the old thread but I think I may answer this question as I used to be a power designer .I guess the problem(Unstable AC output voltage when loads are under 400watts ) is that the feedback loop design of the DC-DC boost stage (12V-300?V) is not a good design , you may measure unstable voltage on the bus capacitor when it operates at 16% of its full loads .By the way , DC-AC is easier to be stable than DC-DC
The Xantrex SW + 5548s here are all in their 12th year -- not an issue with any of they ... yet.
As Marc said, these old SW and SW+ inverters have a very good reputation for ruggedness and longevity.
There are several Trace SW 4048s at neighbor's properties, one dates from 1998, and has been in continuous use since then.
Another neighbor has a pair of Trace SW 5548s that have been in service since about 2000.
The one thought about your system, is that hope that you have as much protection from nearby lightning strikes as possible, although this is probably not the issue with this inverter failure.
Thanks for the report. Vic