Xantrex XW adding a generator

emerika

Anyone know how the Xantrex XW systems works when you're using a generator. Specifically, does the power to the house go through the inverter or is it just dumped there directly.

I'm trying to decide how important the quality of the electrical needs to be. It's a honda generator I'm looking at and frankly we will rarely need it. So far, we've been living on off-grid solar power for nine months now without needing one.

We do run a bunch of computers, TVs etc and I don't want to wreck something with dirty electricity, but I don't want to spend a fortune either.

thoughts?

emerika
http://www.kbtechworks.com/kbranch/blog/?tag=solar

BB.

Re: Xantrex XW adding a generator

Think of the XW Hybrid inverter like a giant UPS without the batteries...

[sorry--visited your website and see you installed an XW system last year--The generator discussion still applies though]

AC1 is typically the Utility Power input. And can also feed back power to the utility (if legal and configured). The default assumption is ~60Hz+/- 0.5 Hz or so frequency and ~212-264 VAC input.

AC2 is typically the Generator Power Input. You can configure it for something like 44-70 Hz range or so (and it will operate correctly), plus you can configure it for even wider AC input voltage too.

AC Out is basically either AC1 to AC Out, or AC2 to AC Out, or Inverter to AC out.

So--while the XW unit can "accept" a very wide range of frequency and voltage--it passes that energy directly through to AC Out through its own internal AC Transfer Switch (and can pull some of the AC power to recharge your battery bank too). It is up to you, more or less, if you want something like 60Hz +/- 0.5 or +/- 1.0 or +/- 5.0 Hz (typical?) or even wider...

Once the XW decides the power is "not good", ti will convert over to AC Inverter Power (from the battery bank) and provide your local electricity.

And while the XW hybrid inverter can do Grid Tied power very nicely, it also appears to be a pretty nice choice for pure off-grid system where there may never be any utility power.

There are a lot of other nifty features too (one interesting one is that you can program it to only take 15 amps of 240 VAC (3,600 VA) and, above that level, it will turn on the inverter and actually assist the generator in supporting your load (say you have a big well pump).

I am no expert in the XW/etc. hardware--but from what I have read/understand, it is a very flexible unit--and for most people, seems to be very reliable.

Regarding "dirty power"--Most electronics these days are pretty good at accepting 50/60 Hz and from ~100 volts to ~264 volts volts (if power factor corrected modern computer power supplies)--or at least able to accept 105-132 VAC 50/60 Hz just fine (and frequencies in and around 50-60 Hz).

If you have transformers or electric motors (fridge, pumps, mechanical devices)--probably +/- 5 Hz is about their limit--And if they have accurate timers running from AC voltage--they will not be very handy as "clocks" from a typical genset.

Usually, what ruins appliances is low line voltage or "Brown Outs"... These days, electric utilities will cut power rather than allow low voltage operations (if they have control over the problem). So, I would look at making sure you are getting at least 106/212 VAC for your typical AC devices.

In the end, measure your loads (peak watts/VA, average watts, hours per day, etc.) and define your needs... Then look for hardware/configurations that will support them.

The Honda eux000i family of gensets are very quite, stable AC power, and quite reliable. Plus they are quite fuel efficient at lower electrical loads... However, any good quality genset should run your loads just fine.

I personally believe in conservation/minimizing your loads--allows you to build a smaller and less expensive solar PV power system. And your maintenance costs are much lower over time too.

However, genset wise, it is difficult to find "small" (below ~5-7.5kW) gensets that are rated for prime power (off grid). And the big ones burn a lot of fuel if you have small loads on them (try to get your gensets to 50% or greater loads for fuel efficiency--and for diesels, longer mechanical life between major service).

-Bill