every once in a while someone will renew a telecom installation
and they will surplus out the inverter system on ebay.
usually they are made by exeltech, and are iirc the mx series, almost always 48volt dC front end, and 117volts 60hz pure sine wave on the back end.
they are rack mount units, hot swappable, about as bullet proof as anything can ever be.
the folks down in fort worth texas (exeltech headquarters) are very good to work with, and will service and provide tech support for their products second to none.
their inverters are the cleanest pure sine wave units on the market, they advertize to be better than 2% harmonic distortion, but in actual use they will be well under that in reality.
i have i think about 20 some kwatts of exeltech inverters, actually i think there is over 30kwatts, i bought them surplus and have less money in them than i would have had in ~5kwatts of new outback inverters... i think it is because everyone knows about outback and they rarely ever come available for a great price... although
i did find on craiglist for a friend of mine a huge outback system, 11kwatts of inverters all on the mounting system, an mx60, distribution panels, mate and other stuff for 3 grand a couple years ago. it was a 2 year old 24volt system that was being replaced on a yacht in seattle.
i kick myself for not buying it for myself!
keep an eye out, sometimes the secondary market will come up with some nice high end stuff well worth the money.
bob g