So - short answer, it costs more and it doesn't happen that often. So contractors don't sell/install it.
Most solar installs work by tying into the existing main breaker of the home.
The cheapest way to do this is to leave the line feeding from the power meter to the main panel untouched. Instead you do anti-islanding detection at the inverters, and when they detect that mains is "down" they automatically cut off to prevent trying to backfeed power to your whole neighborhood during an outage (dangerous, not a good idea).
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Second issue - there are many appliances that are NOT happy about being turned on and off at random times, and it can significantly impact their lifespan (ex - refrigerators, acs, computers, washers & dryers, etc).
So given the variability of direct solar, you don't want to accidentally destroy your ac unit by having it turn on and off 100 times as random clouds float by.
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But! If you're willing to install even moderate battery capacity (and LFP is getting quite cheap as well). Then you can absolutely do this. It's just more complicated and more expensive.
You need to wire in a mains relay (~$1,000 depending on the unit) and install some battery capacity to prevent very frequent startup/shutdown, then go through some painful additional signage and labeling requirements (at least in most of the US) and also install some additional shut-down switches on the exterior of the home (ex - to automatically turn the inverters off, and to shutdown the battery system).
Then, yes, you can absolutely stay on solar power while the grid is down. In the same way that people are allowed to run whole-home generators to stay online when the grid is down.
Thanks, that's a really useful explanation. It sounds like if you forgo using a battery, then you have to be comfortable scurrying around and unplugging some of your devices. (and as silly as that is, you might aggressively power-cycle a device into oblivion before you manage to get everything unplugged. (most people would probably just not settle that sort of plugging / unplugging.)
> It sounds like if you forgo using a battery, then you have to be comfortable scurrying around and unplugging some of your devices.
Pretty much. I vaguely remember a couple of "off-grid" devices that try to automate this for you (ex - you can set a priority on each breaker, and as supply dips, they get dropped in order of priority).
But functionally speaking, you just need to install a battery. Frankly - Batteries aren't discussed as much as solar, but the big breaking point we're hitting right now isn't just that solar has gotten incredibly, unimaginably cheap.
It's that BOTH batteries AND solar are getting very, very cheap. And the new generation of batteries are also considerably safer than the original lithium batteries.
Lithium Iron Phosphate batteries (LFP) are ~$60/kWh right now. I can buy them commercially in bulk in the US around ~$80 (pretty much all china production - full stop. Historically, I've bought EVE cells, but I'm now seeing direct BYD branded cells as well).
If sodium-ion can hit the same price points (and odds are looking better and better they'll both hit and then plow past as they bulk up production) then my read is that modern power plants are going to be very, very different.
They'll look a lot more like the connection structures we see for trees - a bunch of connected independent installs that can optionally cooperate as needed. Ex https://www.bbc.com/future/article/20260928-a-virtual-power-...
Thanks for the detailed explanation. Can we connect? Email on my profile. I run a non-profit, I teach middle/high-school and college kids about building codes and the first thing I have them do is find out the county building code engineers[1] and ask them to update the code: require 240V outlets in the garage for EV charging. After they know how to do this, the next steps are to require 240V outlet for heat pump water heater, induction stove (solves indoor air pollution), heat pump HVAC. Everything can be electric. Finally, build the house with solar panels on the roof.
Home circuitry, load center need to be redesigned for V2X (vehicle to grid, home, load, etc), plug-in solar and batteries, solar/batteries replacing generators, etc. You seem to have thoughtful ideas about these and it would help to have someone knowledgable articulate how it should be done.
[1]The idea is that they can change the world right now by understanding what they want in their world (clean and free energy) and that they need to ask for those changes because buildings last ~100 years. The lowest hanging fruit is future-proof all construction and have it be ready for incremental changes without needing any labor or permitting work.
Asking kids to push your political goals under the guise of “education” feels pretty icky.