Net Metering: Why you can add a Sunny Boy Storage to a single or 3-phase PV system

As some of the users have already pointed out, not all countries have net metering done in utility meters. SMA should at least provide an option to switch to per phase metering mode and only try to keep power at 0W on the phase where battery inverter is connected to. Feeding in to grid makes no sense in this case, as solar energy ends up in the grid by first passing through the battery, which wears it down and a substantial percent of energy is lost in heat.
Similar problem exists with EV charger if net metering is not available. Surplus power should be monitored on the phase where single-phase charger is connected, or in case of 3-phase charger, charging current should be set based on phase with the least available surplus power, or some importing of power from the grid will happen.

Hi, to everyone not in Germany, not in Australia and Denmark, and even in these countries, beware that if you not signed feed-in contracts with your grid operator and have ordinary electronic grid counter, many grid counter models are NOT designed for bidirectional and they will count the electricity irrespective of the current (energy flow) direction!!! This is the case I am finding when asked for help at many cost-burned customers who attempted to use Sunny Boy/Island battery systems+Tripower solar inverters without signing the feed-in contract and without replacing the meter to bidirectional meter, just using the grid as generator. Huge bills are received despite that feed-in is set to zero, and SMA Home Manager 2.0 counters showing zero grid usage. In my own first lesson, it was 1.6kWh at SMA HM 2.0 counter and over 3000kWh on grid counter for the on-grid system that was not consuming and not-exporting! Let me explain the reason for this by example: when 3 phase load, let’s say heat pump at 6kW (2kW per phase x3 phases), is on, and single phase on-grid battery system generates 6kW into phase L1, to get net zero, the end result will be +4kW on L1, -2kW on L2, and -2kW on L3. Standard not bidirectional electronic grid counter will count as if there is 8kW of the load (4+2+2), that is, your kWh number to pay for will increase by 8kWh per hour, even if SMA HM 2.0 will measure net zero for that hour. Therefore, if you will disconnect the on-grid battery system at all, the counter will add just 6kWh per hour. That is what the confused customer is observing in the comments above. That is the reason of getting even higher invoices from the grid after installing battery systems that are not designed or do not care to keep all 3 phase currents at zero at metering (grid connection) point.
Then, even after you will install bidirectional counter (that is only possible, in many countries, if solar panels/inverter is installed and commissioned), the accounting (net metering) is completely separate for each phase. Local grid operator is specifically explaining, that if there is a generation into one phase, that is feed-in, and if there is a consumption on another phase(s) at same time, that is purchase. As the price difference will be about 50%, depending on country regulations or grid operator tariffs, to achieve real net zero in the net metering bill, twice more energy should be generated into grid on L1, than there is consumption from L2/L3, to stay at zero net cost. Phase balancing is very costly grid service, and unfortunately every morning and evening we use a lot of this grid service. SW/logic upgrades in the SMA products are required to avoid this cost.
This is what is much, much wanted from SMA by customers in many countries:
a) ability to setup “Per phase grid metering” for Sunny Portal, for all statistics (counters) to work/count correctly in a countries with per-phase metering, and show two numbers (one in red, another in green) when there is both consumption (on some phases), and generation (on another phases) at same time, account in the app accordingly (account more for “Purchased”, “Grid feed-in”, and less for “Direct consumption” accordingly)
b) ability to setup “Cover loads in other phases before starting feed-in” parameter for Sunny Island when grid is on, specifically for off-grid setups with grid connected instead of generator, which is the only reasonable Sunny Island (SI) investment usage for modern smart-homes, to avoid black-outs and have transfer to battery duration at 20ms. The SI top efficiency is above 95%, so even with energy passed from one SI to another SI device, close to 90% of energy will be delivered to another phase, the 90% is much higher cost efficiency compared to 50% cost of grid based phase balancing,
c) if technically possible, in “Per phase grid metering=ON” situations, while inverters are not operating at their full loads, up to Tripower inverter per phase max. power capabilities, they shall directly generate more into particular phases where there is more load, to minimize the cheap feed-in and costly purchase at the same time.
d) one phase EV charging must not be triggered in homes with “Per phase grid metering=ON”.

In general, the things shown in this article may be considered as a form of grid abuse, even in Germany or Australia where sum of 3 phases are net-counted, as the currents to balance between phases will travel via grid outside the home, so there will be losses (in lines to transformer), and that means other customers will pay for the phase balancing current losses – even if that seems to be for free from the grid side. Company so big, so responsible, so green and so grid friendly as SMA needs to be, shall do everything possible to balance the phase load before the grid connection/grid meter point, not behind it at someone else’s cost. No current outside home flows for free (without loss), even if the grid in Germany is too much positive in accounting terms, this turns back against consumers in the forms of various over-regulations (various extra limits and permissions that are not needed elsewhere, etc.), compared to other countries where you can do whatever you want – but you pay for everything what you use.
SMA is a high quality brand, for me it sounds as “Solar Mercedes”, with “Best or Nothing” philosophy on products. I hope these needs above to cover phase based net-metering are being developed and will come in future product SW updates, as SMA products are not for Germany only, and the needs of the customers in the countries with per-phase net metering will be respected.
My home:
2xSMA Tripower 20000TL-30, panels both on the roof and on south walls of the home
30kW feed-in permission, 80kW usage permission, phase based net metering
3xSunny Island 6.0H, off-grid mode with grid connected as generator, one Tripower and all protected 24×7 loads are behind SI 6.0H (in the “always on island”)
60kWh VRLA 48V battery string
SMA 2x EV 22kW chargers, just ordered, on the way.
I am SMA products enthusiast. Former electrician.