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Comment by dotancohen | Hacker News Reader

From what I understand, most homes that are connected to both solar and the grid require the grid to be active to produce solar. This is for two reasons. One, not to endanger lineman working on the grid. And two, the solar AC cycle must be synchronized with the grid AC cycle.

Are these homes not also connected to the grid? Or is there some technology that addresses these two issues that are in use in Puerto Rico?

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I think you're looking for the term "islanding".

It's becoming more and more common for PV systems with a battery system to be able to work in an islanded mode, and more importantly - they're legal and code compliant to do so.

When the grid goes down/out of spec, they disconnect the home from the grid and continue to power locally.

Examples of this include Tesla and Sigenergy.

Some are able to do this in very short periods and able to operate effectively as a whole-house UPS. Some will have a flickr of the lights and maybe some sensitive devices will restart. Others will take some period of time to disconnect from the grid and run in islanded mode.

For general interest, Western Australia's State Power company has a variety of battery application cases that it assists with; home batteries, community batteries, fully stand alone, microgrids (with batteries).

https://www.westernpower.com.au/resources-education/consumer...

https://www.wa.gov.au/organisation/energy-policy-wa/wa-resid...

West and South Australia are a fair way down the integrated renewables pathway with a high percentage of household rooftop solar, mixed rural PV farms, wind power, battery farms, etc.

If you use a string inverter not a emphase style microinverter, most of them are capable of running without the grid- Particularly if you add any sort of battery system.

These use a form of transfer switch like you’d use when you connect a generator- they disconnect the upstream.

You can run sans grid with Enphase (with their "system controller").

If your home is isolated from the grid you don't have to worry about syncing your 50/60 Hz. A UPS during a blackout is an example. I experienced it myself.

I have no idea about the hurdles of keeping in sync many batteries in many homes connected together. This is not even something I thought about before the news of the blackout in Spain months ago.

Keeping in sync isn't as much of a problem as you might think, it simply requires that everything able to feed into the grid has to accept the grid as authoritative for syncing.

Relevant are some of Chris Boden's videos about bringing up a hydro power plant and his comment that you have to be in sync with the grid when you actually connect because the turbine WILL sync to the grid at connection and if it was incorrect before then there will be a lot of loud angry noises from the equipment. https://www.youtube.com/watch?v=xGQxSJmadm0

This is true, but if you add in local batteries attached to the solar, you can have a device that works in basically all situations. If disconnected from the grid, it can run off battery instead of just not working.

I haven't read the OP link yet, but my guess is they are doing something like this: Grid, Solar and batteries.

"Grid, Solar and batteries."

They are doing microgrids, that connect to each other.

Aka a grid. Sure, this is a newer version of the grid, that allows local failover, but it's just a grid.

Maybe we can upgrade the other grids to do this too. That would be fabulous.

Microgrids use specialized inverters with islanding capability and automatic transfer switches that disconnect from the main grid during outages, allowing them to operate independently while maintaining their own frequency regulation.

It's just a coordination problem.

You are also sort of conflating "loss of interconnect" with "outage'.

What is the difference?

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