From what I’m learning in this thread, no - what you say may be true, but it’s irrelevant. The power generated by your solar panels is just feeding back into the dead grid, so you are getting nothing from it.
Huh. I thought it basically fed your in-house wiring, and any excess went back out to the grid, or any deficit came in from the grid.
This take matches my understanding – ie, it’s by design:
The only thing a properly installed solar system needs to generate free electricity is sunlight. So why can’t you use this electricity in your own home or business when the grid goes down?
It’s because of how a grid-tied solar system works. Sunlight hits the panels, generates electricity, passes through the inverter, and is used to turn on your lights or keep your food cold. When your panels are producing more electricity than you’re using, the extra electricity is pushed onto the electric grid.
If the electric grid is down and your solar system is pushing that extra electricity onto the grid, that’s a big problem.
Utility workers are working on those same power lines fixing the issue to get the area back up and running. They are doing this with the assumption that the lines are dead. Electricity from your solar system would make that assumption incorrect and can cause serious problems. In order to protect the utility workers and the grid itself, all grid-tied solar energy inverters are required to automatically shut down when the grid goes down and the power goes off.
So … yeah … an ‘off-grid’ system, replete with battery storage, solves this problem.
Thanks. So what I said wasn’t really accurate, but the outcome is the same.
So there’s not a way to make a “valve” type circuit that would basically prevent that extra electricity from going to the grid, if it’s down?
I mean, most people would think it’s better to just do something superfluous like heat up some random heating elements somewhere with that extra power, rather than be shut down in a power outage. Or if battery capacity is available, then into the batteries.
Tesla Powerwall:
When the power goes out–whether from a storm or an earthquake–solar energy systems are designed to immediately shutdown to prevent power being sent back to the grid, which can endanger line workers.
But when you have a storage system like Tesla Powerwall, you can still draw power from your solar panels and store it locally while not sending any of it back to the grid.
https://www.a-rsolar.com/learn/battery-storage-home/?utm_source=google&utm_medium=cpc&utm_campaign=dsa_wwa&utm_id=12247588210&utm_term=&gclid=CjwKCAiAyc2BBhAaEiwA44-wW0c2fb5-ImS4c5kly2YTCJSG0CjnWM3pUatXnHrZs3fNxHh2qAcusBoCMBUQAvD_BwE
I think it’s doable:
https://www.cpuc.ca.gov/PSPSFAQ/
[NB: Canadian site]
- Can I use my solar panels to provide backup power in the event of a power shut-off?
Maybe. During a power shut-off, most solar systems will automatically power down. This behavior prevents any flow of power into your utility’s de-energized electric grid and is essential to ensure the safety of repair crews and first responders. However, while many solar systems are designed to operate only while the grid is operating normally, some systems have the ability to “island” during outage conditions and provide power to some or all of the appliances in your home.
Please check with your solar provider and/or your licensed contractor to determine the capabilities of your specific system.
What I don’t know is if the utility companies – particularly US-based – will even allow it. Belt and suspenders and all. If that ‘check valve’ fails, then they really do have another problem to contend with.
Any chance you know how much luck they’ve had in utility companies allowing the grid tie-in and power-failure operation mode ?
This would be a big win for companies like Tesla (and other solar providers), but I’m not aware of where they stand on major electricity utilities agreeing.
I don’t know. However, I have asked for a bid for our house. So, I’ll know soon, perhaps.
IIRC, one big problem with generators operating during a power outage is the danger of feeding power back into the outside lines. That puts the power company workers at danger working on the lines. Your house must be completely isolated from the delivery lines for you to run power through your wiring.
Don’t you need exactly the same sort of transfer switch that a house with an electric generator would have installed?
It sounds like the ATS’s you’re talking about are ‘in on the game:’
The question and answer are, collectively, quick reads. Sounds like code trumps all in terms of protecting the utility, its equipment, and its people if you’re grid-tied.
'Nother source:
Yes, you would. I’m not conversant with how exactly a house generator switch works.
I do know that the store I work in has some sort of system that not only automatically starts up the emergency generators when the grid fails, but it also isolates the store from the grid until it comes time to turn off the generators and re-join the grid. All of which is supposed to work without the need for human intervention.
There is a way, but you still need the batteries. Minimum cost is going be around $5000 as of maybe 4 years ago.
These systems have been around for at least 20 years now. The price is slowly dropping but it is pricey in addition to the cost of the panels. Most people rarely need the ability to generate with the grid off, so most of us don’t pay the extra $5-10k for the capacity.
If all you’re running is a heater, then a direct hookup to a solar panel shouldn’t be a problem. But for almost everything else, a non-grid, non-battery solar system will be dangerously unstable. Most things that people would want electricity for really don’t like unpredictable variation in their power supply.
This isn’t rocket science, it is pretty basic electrical engineering and mostly just electrical common sense. Electronics need a solid voltage and thus no direct hookup. Panels charge batteries that go to a rectifier to power your stuff.
At the same time, please don’t be that jerk that powers their breaker panel without isolating it. That is for batteries or a generator.
There are auto-sensing switches or just make sure you have a clean, easy to read instruction set that starts with shutting off your connection to the street and your breakers before powering off-grid. Then you selectively turn on the breakers you want to power. Do the math and match what the load you want to run is versus the running capacity of your generator or battery set.
Your 10kw generator is peak 10k but probably only around 7200w normal load. Then you have to start figuring out what fits the 7200w.
Perhaps events in Texas suggest that there could be a market for a simple and much cheaper arrangement to switch your solar power to just heating an electric radiator if the grid goes down? That heat could be very valuable.
Texas is an interesting case.
What is the most popular heating options? In San Diego it was a small electric wall heater. I don’t think most of Texas is quite that warm in the winter though.
Is it electric, oil, gas or propane?
If the fuel isn’t electric, you generally don’t need a lot of power to run the heat. I had baseboard in the last place and could run the boiler on about 1 amp. So my little generator was fine for that except that the little propane tank froze up when it started getting low.
Now I have gas but forced air and my generator couldn’t run that, but smallish Generac would do a great job of running that and other stuff.
I think heat pumps might be popular in Texas, I feel like they are in other very southern states. They’re usually pretty efficient but don’t run so great when it gets really cold.
Maybe a push for better solar backup systems with cheaper auto transfer switches will happen. That would be good.
When we put in our solar, we bought an inverter. Basically, we can throw a switch to go off-grid and thus use the power generated. No batteries, so it’s a daytime option. We have only a small number of panels, but in theory it’s enough to keep the big freezer cool. We have a variety of solar travel chargers for phones.