Hi, I am looking at purchasing a 5KVA mecer inverter. my question is if  I have 900W of solar panels and I need 3KW to run appliances do I use the 900W from the panels and can I add the other 2.1KW from my utility or how does this unit operate regarding solar,batteries and utility supply?

Thanks

11 minutes ago, Elroy said:

if  I have 900W of solar panels and I need 3KW to run appliances do I use the 900W from the panels and can I add the other 2.1KW from my utility

Welcome Elroy.

With the Mecer you will not be able to do that. If the demand is to big for the DC supply it will take the full load from the Grid. You will need a full hybrid inverter to blend different power sources. Something like Infinisolar, Victron, Goodwe and some other brands 

As I understand it,  if the load exceeds what your panels and batteries can provide,  then the inverter switches tu utility to power the load. 

If your load is 3KW constantly then your inverter just becomes very expensive battery charger. 

13 hours ago, Elroy said:

I have 900W of solar panels and I need 3KW to run appliances do I use the 900W from the panels and can I add the other 2.1KW from my utility

The Axpert King (I believe Mecer rebrands one as a SOL-I-AX-5KP), the it can do that. Supposedly some of the models that have a 450 V max Solar Charge Controller can also do it, but possibly only under certain conditions, and they may trip meters by accidentally exporting small amounts of energy when loads decrease suddenly. The Axpert King / SOL-I-AX-5KP won't have that problem, due to its double conversion nature.

With the other Mecer models, it's not so bad. When you need 3 kW (presumably for short periods of time), the battery supplies the extra 2.1 kW plus losses, and if it's low, the utility supplies the whole load, for 10 minutes if the 3 kW demand is short (2 minutes for most patched firmware). During that time when the utility supplies the loads, all the solar charging goes into the battery, making it less likely that the next 3 kW demand has to come from utility.