There is an awful lot of confusion (and misinformation) out there about the practicalities of installing single phase solar on a house that has a 3 phase supply.
Now that Feed In Tariffs are generally between 6 and 10c per kWh, compared to an electricity price of 30c or more , naturally people installing solar want to self consume as much of their solar energy as possible and minimise the flow of exported solar electricity.
So most of the emails we get these days about 3 phase worry that if they choose to install solar all on a single phase they will lose out. They worry that any electricity they use on the 2 phases that are not connected to solar will all be imported at 30c per kWh no matter how much solar they are generating on the solar phase .
We have never seen an installation where this happens. All the 3 phase meters that we have seen 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. if you are on a stingy FiT, they don’t penalise you financially for having a single phase inverter on a 3 phase supply.