We collected data from a solar photovoltaic system installed into a 5-bedroom property in the UK.  We collected real data from this system and this is we learn from our off-grid system

Solar inverter that are classified as off-grid they do not export energy back to the grid. The grid operator will not have issues if you connect one or more inverters since they will withdraw power from the grid (when battery are charged through the inverters) like any other electrical appliance.

Grid Export: 0kWh

Grid Import: In 12 months we bought from the grid 5,200kWh or 5.2MWh.

Solar Energy Produced: 4,800kWh or 4.8MWh

Home Energy Used: 8,200kWh or 8.2MWh

The energy that was imported from the grid was bought at a low rate, the family is charging the batteries and electric vehicle only at night using a 4-hour window with a reduced tariff from Octopus GO.

Solar PV Off-Grid System – Specifications

The system consists of 24 solar panels from Renesolar 400Watt, the total installed power is 9600Watt.
There is a battery bank of 8x US3000C Pylontech batteries, the technology is Lithium Ion Phosphate.

The use of electricity is quite excessive for a house but having two small electric vehicles it will impact the dependence of the national grid. The combined energy storage of two cars is 70kWh.