It appears that PLN Indonesia is calculating import and export in 3 Phase Net Metering systems in way that is different from the rest of the world.
In most of the world utilities nets the import and export on all phases. e.g. exporting 4kW on L1 and importing 1kW on both L2 and L3, results in recording net exporting 2kW.
PLN, in contrast, does not net the import and export on all phases. e.g. exporting 4kW on L1 and importing 1kW on both L2 and L3, results in recording exporting 4kW and IMPORTING 2kW.
Due to PLN regulation of only crediting 0.65 per 1 kWh exported, this in effect means that PLN only calculates Net export of (4kW x 0.65) min 2kW = 0.6KW instead of 2kW x 0.65 = 1.3kW. Might not seem a lot but over a month it can add up.
This brings me to the importance of 3 phase balancing. All good electricians try to balance 3P systems. Unbalanced systems create all kinds of problems for 3P motors and other 3P loads. Unbalanced three-phase AC power
PLN’s 3P Net Metering policy is another reason to properly balance your system. You want to minimize simultaneous export and import to maximize your Solar system capacity.
To balance your system you need continuous monitoring. Now and then measuring Phase loads with a hand tool helps, but will not provide you with a complete picture of your phase loads over a period.
This system has deployed our eMon Energy Monitor in his solar system. To his surprise he was frequently exporting and importing simultaneously. He never knew that. On November 22 a skilled electrician rebalanced his system. We calculated that this rebalancing will save the customer around Rp 700k per month.