| From an academic research scientist that works on energy system analysis: In addition to outputting telemetry data about a solar array's production - whether that is meant to be used for the homeowner to monitor their system's performance or a third party to use for SRECs verification - the IoT modules on modern PV inverters are increasingly being designed/included for the purpose of receiving external input signals. These would either come from the local utility, distribution system operator, or regional balancing authority - and would communicate the need to change the inverter module's mode of operation to ensure the stability of the distribution circuit that it was interconnected to. Small scale utility customers are typically only billed for the "real power" that they consume (real power is metered in kilowatt hours, kWh). This billing can come in different incarnations - i.e. volumetric tariffs, time-of-use tariffs, net-metering tariffs (as with bi-directional solar metering). However, in order to operate a reliable AC power distribution system you need to also be concerned with the supply of "reactive power" (metered in kilovolts-amps reactive, kVA). Reactive power is consumed by inductive loads (like electric motors) in large volumes particularly when starting up. Moreover, reactive power cannot easily be transmitted over long distances in the same way that real power can. The consumption of reactive power can cause the voltage and current curves of an AC power flow to shift out of phase with respect to one another. This effectively reduces the apparent power delivered by the system. This can also cause other problems with maintaining the system's nominal frequency and voltage. Large AC generator units, that are essentially comprised of a large spinning mass ( such as a natural gas turbine for example) naturally output a more even balance of real and reactive power components. However, when you try to replace these units with lots of small DC generators, like solar panels, whose AC power characteristics are determined by the design of the inverter modules, what you end up finding is that there is a deficit of reactive power supply. Inverter modules can technically be setup to produce reactive power - but they generally are not tuned to do so. This is because it detracts from the amount of real power that they produce. And remember, that real power is the only thing that you get paid for under a net-metering tariff. There are currently no markets which would compensate you as a homeowner for the production of reactive power. So, with the knowledge that many of these inverter systems will have 10-15 year lifespans once installed - and that grid operators will likely need to call upon them in the future to dynamically control the supply of reactive power at certain locations (particularly as more renewables come online) regulators are increasingly requiring that all new inverters have networked communications capability so that they will be ready once such a command-and-control protocol is eventually developed and implemented. |
- [IEEE 1547-2018 - proprietary](https://standards.ieee.org/ieee/1547/5915/)
- [CA energy commission 2020](https://www.energy.ca.gov/sites/default/files/2021-05/CEC-50...)
- [IEEE power and energy commission report 2020](https://www.nrel.gov/grid/ieee-standard-1547/assets/pdfs/sma...)
AFAICT, the mandate to permit not only network connection but control is coming, but the security of this link was expressly deferred.