tldr: How do I adjust the power being dumped by my grid tie inverter? Is it possible to use a constant-current power supply to do so?
I am planning create a PV system that will help reduce my electric bill. However, here in my place, net metering is not really a thing which means that there's no use injecting power back into the grid. I was planning however to monitor my power consumption to closely match it and let the grid tie inverter output the power that I am using. For example, if my house is using 300w, I will adjust my 1000w grid tie inverter to output 280~300w of power. However, if I see that the house is using 1500w (for example, a water heater running), I will just let the grid tie inverter output 1000w and get the extra 500w from the grid.
I was originally thinking of connecting the batteries directly to the grid-tie inverter and use some kind of DIY solution to increase-reduce the voltage but based on my research, I don't think the inverter would like it, as they are usually designed to be connected directly to a constant-current power supply i.e. solar panels. Is this true? Will I be forced to use a constant current power supply (that has to deliver up to 1000w of power)? Or am I missing something here?