I read the manual of a voltronic axpert king 3kw 24v inverter and it says that the inverter can be programmed  S(solar first)U(utility second)B(battery last). No information otherwise. Ergo, I can ground that the inverter can be used without batteries . However, several commercial agents I have consulted are telling me that Axpert King inverter "CANNOT" be run without batteries and only Axpert VM inverters can. Have any member of the forum run an Axpert king without batteries? Is that possible?  the reason for this question: I have a microhydroturbine harris 1kw, 50-80 vdc  to add to a  5kw solar system with a 9 kwh battery bank  during the winter months  to keep up an off-grid home happy; the basic idea is to dump the electricity from the hydroturbine as 220 VAC into the utility port of my axpert VM IIII in a USB configuration.  THANKS!

6 hours ago, koldo said:

Ergo, I can ground that the inverter can be used without batteries .

No, that doesn't follow.

6 hours ago, koldo said:

several commercial agents I have consulted are telling me that Axpert King inverter "CANNOT" be run without batteries and only Axpert VM inverters can.

Not quite true. All models with the higher voltage PV can operate batteryless, if they have reasonably recent firmware, I believe. So MKS II, III, IV, and I think even Max, and King II.

6 hours ago, koldo said:

Have any member of the forum run an Axpert king without batteries?

I believe that the Axpert King II with the higher voltage SCC should be able to operate batteryless. But I have not confirmed that by either reading a manual, or checking firmware.

7 hours ago, koldo said:

However, several commercial agents I have consulted are telling me that Axpert King inverter "CANNOT" be run without batteries and only Axpert VM inverters can.

They were likely told to say this for all of the Axperts... I know that the MKS range need DC voltage to turn on so many agents will refuse to sell one without a battery, where the 5,6/8kW VM are able to run off mains. This is because they are hybrid units where the Kings are off-grid units, meaning the system is designed to run without grid connection. So solar might work if up to date as Master @Coulombmentioned, just be ready for the system to be painful when light levels are low. Had a sight where they wanted to run an off-grid as grid tied, basically using solar to supplement their grid and reduce electricity costs and it was a mess. Early mornings and late afternoons the entire system would fall over and we ended up adding batteries to the system later...

18 hours ago, koldo said:

I read the manual of a voltronic axpert king 3kw 24v inverter and it says that the inverter can be programmed  S(solar first)U(utility second)B(battery last). No information otherwise. Ergo, I can ground that the inverter can be used without batteries . However, several commercial agents I have consulted are telling me that Axpert King inverter "CANNOT" be run without batteries and only Axpert VM inverters can. Have any member of the forum run an Axpert king without batteries? Is that possible?  the reason for this question: I have a microhydroturbine harris 1kw, 50-80 vdc  to add to a  5kw solar system with a 9 kwh battery bank  during the winter months  to keep up an off-grid home happy; the basic idea is to dump the electricity from the hydroturbine as 220 VAC into the utility port of my axpert VM IIII in a USB configuration.  THANKS!

Just like @Coulombmentioned @Steve87will tell you everything you need to know about these inverters. Yes all the latest 400V+ should be able to run without an battery.

There are also a lot of installers that don't know yet you can run pure grid tied inverter without a battery and yes most if not all you cannot use a battery.

People have got used to the idea when having an inverter it is to use a battery for power when Eskom is down.