Billing for electricity

It is a little more complex than just the capacity of the battery. First of all, it is about the combined capacity of all the inverters. Up to 5 kVA (which is roughly equivalent to kW), there is no problem. Your digital meter counts both the supply and the return of electricity. If you have a battery that is larger than the capacity from your inverters, you may feed back a maximum of the capacity from your inverters (this is to prevent you from fully charging your battery when the tariff is very low or negative and feeding it back when the tariff is high (because then you incur double distribution costs and also make a profit). You can read your supply and feed-in from the display on your digital electricity meter. You can read the meter readings 1.8.1 (incoming electricity peak hours), 1.8.2 (incoming electricity off-peak hours) 2.8.1 (feed-in peak hours) and 2.8.2 (feed-in off-peak hours). Or download them via mijn.fluvius.be. You can also activate the P1 port on your meter and connect a logger to it, which you can then read via an app on your phone or PC.If the capacity of your inverters is between 5 kVA and 25 kVA, you must have a multi-phase connection (normally a single-phase connection with a maximum of 40A) unless you need 380V/400V for your machines. In most cases, Fluvius will install two separate meters: one for the incoming power (which does not have any feed-in) and a second meter for the feed-in. If you have a wind turbine or a CHP installation, you will also have a separate second meter.If the combined capacity of your inverters exceeds 10 kVA, you will indeed need a vAT number (and therefore also register as self-employed (whether or not as a secondary occupation) and join a social secretariat) and invoice your energy supplier. At the same time, your energy supplier will also invoice you for the distribution costs (because you use the Fluvius grid for the feed-in) and sometimes even for the electricity fed back (if the price is negative).

If your energy supplier invoices you for the feed-in, switch quickly to an other supplier that does not charge negative prices for feed-in during peak times. Use the V-test on the VREG website. Also check whether a dynamic contract (especially useful if you can regulate your usage smartly by setting heavier appliances to consume during peak production times) or a variable (or fixed) rate contract is best for your situation.
More information can be found at:
https://www.fluvius.be/nl/groene-energie/zonnepanelen/technische-aspecten/omvormer
https://www.minfin.fgov.be/myminfin-web/pages/public/fisconet/document/f938754f-f4e5-4105-8bae-c831af9d71c7/taxable%20solar%20panels
https://vtest.vreg.be/
Johan Vandewalle (Energy expert type A and D)