I need some advice from someone who knows the kodak off grid inverters.

A clients insall
Is running a kodak off grid 5kw inverter with a fox 2.56kWh battery & 6Panels

So when Eskom power is on with a hybrid system i now  that when you go over your 5kw threshold it substitutes from eskom to not overload.
Now Off grids im new to.

This off grid when its on eskom and theres a overload it overloads the unit why doesnt it substitute from eskoms side?

I heard a few theories but i would like to now for sure.

1. What is the transfer switch size on the 5kw off grid inverter?
2. The other thing it could be is overloading of the battery cause the battery size is smaller than the inverter.

As far as I know all Kodak's don't have let through so it can not let through more than 5kw no matter if there is grid or not.

 

I stand to be corrected if there are new models or a model I don't know about that can let through more than its name plate rating. Eg 5kw battery and solar then an extra say 2kw from grid to make it a "7kw"

Edited July 28, 20223 yr by Dylboy

4 hours ago, Dylboy said:

As far as I know all Kodak's don't have let through so it can not let through more than 5kw no matter if there is grid or not.

 

I stand to be corrected if there are new models or a model I don't know about that can let through more than its name plate rating. Eg 5kw battery and solar then an extra say 2kw from grid to make it a "7kw"

On the blending versions with 450V MPPT they don't give the spec for extra power under bypass so it is assumed the total output is the same as the inverter rating.

7 hours ago, MincePie said:

This off grid when its on eskom and there's an overload it overloads the unit why doesn't it substitute from eskom's side?

I heard a few theories but i would like to now for sure.

1. What is the transfer switch size on the 5kw off grid inverter?

I think the issue is that for so-called off-grid models, utility power has to flow through the unit, via the transfer switch if you like. The transfer switch is essentially two 40 A relays (for 5 kVA models) on the main PCB, so all the AC-in and AC-out current flows through PCB tracks. These seem to be sized for the rated output of the inverter, not for the 40 A that the relay contacts are rated to carry.

I think if they connected the relays via appropriate bus bars or a separate PCB with extra thick PCB traces off the main PCB and tweaked the firmware slightly, then it could and would operate as we expect it to, i.e. when bypassing, it can bypass up to 40 A or some 9 kVA, even though the main DC-AC converter is only rated for 5 kVA.

Most models have a "bypass on overload" setting, which doesn't make much sense if you can't bypass any more current than you can invert.

3 hours ago, Scorp007 said:

On the blending versions with 450V MPPT they don't give the spec for extra power under bypass so it is assumed the total output is the same as the inverter rating.

Ah ok sot then if I understand correct then the 5kw is the most it would do, no more even in bypass.

7 minutes ago, Dylboy said:

Ah ok sot then if I understand correct then the 5kw is the most it would do, no more even in bypass.

Coulomb gave a great reply on the short coming of the PCB tracks from the relay contacts. Also some if not all have a thermal trip switch that trips just a bit above the inverter rating from any source of supply. Hand reset.

1 hour ago, Coulomb said:

I think the issue is that for so-called off-grid models, utility power has to flow through the unit, via the transfer switch if you like. The transfer switch is essentially two 40 A relays (for 5 kVA models) on the main PCB, so all the AC-in and AC-out current flows through PCB tracks. These seem to be sized for the rated output of the inverter, not for the 40 A that the relay contacts are rated to carry.

I think if they connected the relays via appropriate bus bars or a separate PCB with extra thick PCB traces off the main PCB and tweaked the firmware slightly, then it could and would operate as we expect it to, i.e. when bypassing, it can bypass up to 40 A or some 9 kVA, even though the main DC-AC converter is only rated for 5 kVA.

Most models have a "bypass on overload" setting, which doesn't make much sense if you can't bypass any more current than you can invert.

I missed this reply sorry but that makes a lot of sense.

 

Then the ones with Let through or Bypass have either a second track or a higher rated track. 

I do want to add, to me, Bypass means Bypass the entire system i.e no battery or PV only grid going through the inverter. 

Any load on Bypass is then straight grid and not powered at all by PV or battery. 

On 2022/07/31 at 4:10 AM, Dylboy said:

I do want to add, to me, Bypass means Bypass the entire system i.e no battery or PV only grid going through the inverter.

Yes, and early models worked that way. But many later models can blend utility power with solar power when in a bypass-like mode, with AC-in connected directly to AC-out via two printed circuit board relays, but with the inverter in parallel with both.

You didn't say what Kodak 5 kW inverter you have; some allow this and others don't. Though most (perhaps all Kodak branded models) allow this blending in SUB output source priority.

From what I picked up the OG cannot run parallel. The OGX can. The the plus version has the 145V MPPT while others have the 450V MPPT.

4 hours ago, Coulomb said:

Yes, and early models worked that way. But many later models can blend utility power with solar power when in a bypass-like mode, with AC-in connected directly to AC-out via two printed circuit board relays, but with the inverter in parallel with both.

You didn't say what Kodak 5 kW inverter you have; some allow this and others don't. Though most (perhaps all Kodak branded models) allow this blending in SUB output source priority.

Ah that is interesting and glad that some newer ones can do the blended bypass of PV and Grid. 

Learn something new everyday haha.

 

So when it says bypass on the little screen and the arrows then go to load, will there then be a PV line thing showing that it too is supplamenting the load ? And I assume this blended bypass is only when there is not enough PV so then it pulls the rest of Grid ? 

19 hours ago, Dylboy said:

So when it says bypass on the little screen and the arrows then go to load, will there then be a PV line thing showing that it too is supplamenting the load ?

If it's blending, then yes I believe so (I don't have such a model).

19 hours ago, Dylboy said:

And I assume this blended bypass is only when there is not enough PV so then it pulls the rest of Grid ?

I think that's how it would normally work, but it may depend on settings.