I'm helping a friend install an Axpert King 5kW (Synapse brand) inverter. Does anyone have specs on the amount of AC passthrough current the device can handle (in ECO mode)? For clarification, that would be the max current the device can handle when grid power is available and the inverter simply bypasses. The Deyes and Sunsynks clearly show their maximum passthrough current on the label, but I haven't been able to find anything concrete for the Axpert devices. I currently specced the input and output terminals to 25A MCBs (5.7kW) but I have seen a few post of forum members stating that passthrough is more likely to be 40A?

Heya, in these situations I usually spec the system as per the units maximum output when running from battery. At the end of the day, you shouldn't have a load larger than the units ability to support anyway. So the 25A is fine, a 40A load running through the inverter may be fine on-grid but it'll burn out the second the power drops... does that make sense? 

My understanding of Axpert units is that the bypass function is still limited to maximum output of the inverter (5kW in your case).

The units are able to handle double that, but for a short period of time (a few seconds), but the continuous rated power is the maximum output of the inverter, whether running mains or batteries.

4 hours ago, recre8 said:

I have seen a few post of forum members stating that passthrough is more likely to be 40A?

I used to think that, because the relays are rated at 40 A, but not long ago I re-read the firmware and came to the conclusion that you'll still get an overload fault code even if you are in bypass mode, and exceed ratings (5 kW continuous, 10 kW for maybe 5-10 seconds, and something in between in power and time). Regardless of whether you are in bypass mode or not.

As Psy points out, with Eskom likely to drop out at any time, you don't want to exceed battery mode ratings anyway.

Plus, all that current is running through printed circuit board tracks, without any reinforcing with copper bars or solid core wires. So it's quite possible that the PCB tracks can't handle 40 A continuous anyway, or even for more than a minute or so.