Note: this article is purely about the financial return of single-phase vs three-phase microinverters. Please bear in mind that we generally recommend using a 3-phase inverter over a single-phase inverter because they balance the phases better leading to a lower voltage rise and have less impact on the wider grid.
We often get asked if using one single-phase inverter on a three-phase supply will affect your financial returns from solar.
The short answer is: No it won't.
The longer answer is:
People on 3 phase supplies considering using a single-phase inverter worry that any electricity they use on the 2 phases that are not connected to solar will all be imported at their consumption rate (typically 30c per kWh) no matter how much solar they are generating on the solar phase. If this were to happen their self-consumption ratio would reduce and their financial returns would reduce too.
This does not happen. All 3 phase meters must take into account the sum of all the electricity being used on all the phases and then subtract that from the amount of solar energy being generated to calculate the import or export amount for billing.
i.e. they don’t penalise you financially for having a single-phase inverter on a 3 phase supply.
For example - If you are exporting 5kW of solar on the blue phase, whilst importing 1kW on the red phase and 2kW on the white phase, the meter will credit you for exporting at a rate of 2kW, because:
5 kW exported - 2 kW imported - 1 kW imported = 2 kW exported.