What does the inverter voltage specifications represent?
I notice some inverter specifications show AC nominal voltage as a single number, such as 208 V or 240 V, etc? And some show nominal voltage as a range such as
- 183 - 229 @ 208 V
- 211 - 264 @ 240 V
- 244 - 305 @ 277 V
What's the difference between these types of inverters?
This is the inverter's AC range (relating to its nominal output). Since grid voltage fluctuates constantly, the inverter has to adjust to that voltage within a given window. For instance, the Xantrex GT5.0 can be installed as a 240v or a 208v inverter, but it can handle grid voltages ranging from 211-264 Vac (240) and 183-229 Vac (208) during times of high or low demand on the grid.
They can also handle a range of frequency as well with the GT5.0 (nominally 60Hz) allowing for anywhere from 59.3 to 60.5 Hz.
This is an indicator of the inverter's resilience in real world operating conditions.
Thanks for the quick reply! So just to be clear -- you're saying some inverters can only be installed at one voltage setting (eg. 208 V) whereas others (like the Xantrex you referenced above) can be installed at more than one voltage?
While I'm at it -- what are the various voltage "steps"? I've seen 120, 208, 240 & 277. Are there more?
The inverters that show one voltage are hiding their range somewhere else in their literature, you just have to dig around for it - they're all about the same. If they didn't have an operating range beyond the (208v for instance) they'd be off more than on...
120/240 are split/single phase - most residential and
277/480 are three phase - most commercial sites. Three phase can get complicated, there's lots to read about on the web. If i can find a good link I'll post it.