Outback FXR series?

dropkick

So has anyone tried the Outback FX-R series yet? Interested in the GridZero feature without going up to a Radian model. (Blend in grid-tie with pv/renewable/battery but never sell it back.)

Ralph Day

I'll let you know. I have one, and a Mate 3, on order. Should be in next week. Every once in a while the venerable Xantrex SW4048 stops working with an "internal relay fault". A thump on the case brings it back to life, but how many CPR episodes can that sticky relay take? Not CPR, but peri-cardial thump like you'd see on TV before CPR would be started.

Ralph

dropkick

We call it percussive maintenance

inMichigan

While waiting (and waiting) for my new meter so I can begin net meter, I'm using Radian's grid-zero to avoid buying from the grid. My battery bank is not sized to carry my night loads, as I'm aiming for grid-tie with selling and net metering. However, since I have the time, I thought I would try to fine tune how I would run in this mode.

Looking at just the batteries, here's what the ebb and flow looks like for 3 days.


Grid-zero has two important parameters: DoD_volts and DoD_amps. I chose the lower voltage limit based on where I wanted to stop my LFP cells. I adjusted the current draw with two limits in mind:
a) Large enough so that I reached DoD_volts a good hour or two before there is enough sun for the CC's to raise the voltage. That is, I wanted to have a 'little draw' somewhat resting voltage to write down.
b) Low enough to avoid unnecessary wear and tear on the batteries, as this mode is not my long term plan. I settled on 0.2C



It works, most of the time. It should always draw 100 watts per Radian, that's how it stays tightly tied to the grid and can respond to a high demand. However, about 10% of time, I find the Radian is going to the grid and not inverting available DC energy. For example during the day, with 14kw of panel, in most weather, nearly all of my house loads can be supported. (test this by opening the grid input breaker, and sure enough, PV supplies what is needed when there is no choice). That is, instead of finding 1300 watts coming from PV and 200 watts from grid, I might find, 300 watts from PV and 1200 from the grid. No fault messages... I'm still troubleshooting with Outback support. I have 4 CC's and FN-DC. I've started to collect screen shots of the system messages, looking for a pattern among the 4 CC's. At such a low load, I'm seeing this funny business happens around the time when 1 or more goes silent. I'm sure we'll fix it. When I find the system being naughty, I quick jump from grid-zero to mini-grid and back snaps it back into line. Hmm, just the act of typing this description for you, I have an idea to investigate...

Caution: Since you would have V_sell (and DoD_volts, they should be the same per OB, and selling is enabled to be able to sell to your self per OB) set low when doing this kind of night time battery drain, if you happen to jump into grid-tie mode long enough to start selling during the day, a Radian will attempt to sell at it's full potential (battery_bank_volts - V_sell). In this mode, there's no limit on the battery current except for my fuse and their breaker...DoD_amp only applies when in grid-zero mode... the current will win.

If I didn't have Net metering, was willing to pay more per kwh (because of the batteries) to avoid buying grid-power and didn't want to upsize the battery bank as large as it would take to become off-grid,
then this is the mode I'd use.

Any specific questions?
inMichigan (Southeast MI)

jimmyaz

Can you guys vouch that both the FXR and Radian GRID ZERO mode is indeed 100% not backfeeding any power to the grid and tripping the smart meter going reverse? 

The idling power usage = 34watts, is this using the GRID power to power itself or DC in?

inMichigan

My Radians draw their power from the DC battery bank.   So even if the grid is present, if the battery bank voltage goes too low, she shuts down (if the charger mode of the Radian is also turned off and the snow on the panels gets too deep).

As for back feeding in 'grid zero' mode, I'll have to test it this weekend.  It's got so many interesting modes, I don't remember if that one did, or if that's the mode that it is using just a little grid power to stay linked up.

inMichigan