I can adjust the output of my Fronius inverter to the grid through a control interface. It's a simple setting. Either in % of output capacity terms or to an absolute kW limit.As you also know there is only 2 way today to shut down Grid-Tie inverters or lower its production utility side:
Some people here are putting in place dynamically controlled systems because they are on wholesale price pass through plans. Dynamic control of their export and/or production enables them to avoid having to pay to export when prices go negative, and they are also dynamically controlling loads as well so as to import as much as they can at such times and be paid to consume. They are doing it now.
There are also quite a number of VPPs operating (virtual power plants) which are remotely controlling home battery systems such that they can operate together as a distributed grid scale battery to provide fast response services to the grid. Even Tesla operates one here but there are quite a number of them in operation.
That's why they have started with pockets of the installed base, so they can test all the various options. As you say, some of the grid options (voltage/frequency signalling etc) can be a bit brutal and indiscriminate. That's why I'd much prefer a simple signal was sent to my inverter which can then control it's own ramp down.I still do not know what type of control they want to use over the inverters ?
The plan is good but the devil is still in the details and in the implementation.
The requirements only apply to grid-tied inverters capable of pushing power into the grid. This is 99% of rooftop PV inverters in Australia.I wrote Hybrid inverter. You know the single unit grid-tie + off-grid inverters (like Voltronic Infinisolar or SAJ H1).
All your house load is going through that inverter. A real house UPS. If you have to put that out to the internet and someone hacks into it then they will know how much is your actual used W (you are home or not).
The sort of inverters you refer to are set up to operate as an off-grid set up only.
Anything connected to the grid which operates as a small scale generator (SSG is defined as something which supplies power to the grid) requires power distribution authority approval and is required to meet specific standards (including any set limits on capacity and export controls).
An inverter operating off-grid which does not back-feed power to the grid (even one that can pass through the grid power and operate like a UPS) is not subject to the same requirements that grid tied inverters are. As far as the grid is concerned such inverters are just a load. If the grid goes off-line, then as far as the grid is concerned that entire load has been removed from the grid (if it wasn't already sourcing power from off-grid supply).
I have both such set ups at home:
- A grid tied Fronius inverter which can pump power into to the grid. It operates in parallel with the grid supply. If grid goes down, so it does too.
- An AIO unit which operates with a separate PV array and battery. This supplies power to off-grid AC outlets plus provides backup to my home via a transfer switch, meaning those backed up circuits are completely isolated from the grid and so become an extension of the off-grid outlets. It can operate in the manner you describe, i.e. accept grid power in and pass through to output, and cut over like a UPS if grid power is cut. These operate in series with grid power and as such connected loads are limited to the output capacity of the inverter (there is no parallel supplementation of power from the grid). Provided they cannot supply power into the grid, then they are not subject to the same grid control requirements.
As to the risk hacking presents to grid stability, I see little difference between the risk of distributed rooftop solar supply being hacked and any one of the large grid power stations being hacked. They are all connected by networks and are all hackable.