Request information about off grid inverter


Dear Marin,

I hope you are fine.

Let me introduce myself to you , I am Ashraf from Energetus which is an EPC company for power plant installation based in Muscat.

We were requested to design an off grid solar system with no batteries for a container with AC, light, electric kettle and fridge.

In order to use electricity at night we are going to use a basic generator. This generator will be operated manually.

Note would prefer not to use the generator at day time in order to save fuel. We would disconnect it as soon as the solar power is enough for the consumption.

We would like to suggest to the Client to install a 5 kW inverter.

Could you please advise us what is your suggested inverter? Also, regarding the connection (considering both inverter and generator are connected to the same switchboard), what will be the effect of the generator switching on/off every day? I believe we should consider an inverter that does not require power from a grid to start working?

Looking forward to hear from you soon, I wish you a good day.


Hi Ashraf,

It is almost impossible to combine a generator and solar in an off-grid installation without a battery. The problem is the generator needs to be running for the solar inverter to operate (and synchronise). You really need an off-grid (multi-mode) inverter/charger with at least a small battery to start the system. The multi-mode inverter will control the generator as well and makes the system work seemlessly.
The Selectronic SP PRO inverter is very good but if you cannot get this then the Victron Multiplus or Quattro inverters are also good options. The multi-mode inverter will need to be AC coupled with a compatible solar inverter (Fronius Primo will work with both the SP PRO and Victron).

Hope this helps, sounds like you need to talk to a local solar professional



Hello Jason,
Thanks for your favorable replay.


Regrading the topic above , I would like to ask if there is a generator with same voltage and frequency that required from the inverter to be synchronize , can we designed off_grid under this condition ?


It is very dangerous to connect a solar inverter to a generator. If the load drops to zero then the solar inverter will try to force power back to the generator and will damage it. You need a multi-mode inverter/charger with a small battery and generator control. Victron inverters are the best option but maybe other options available in your country


Thanks …