Rooftop Solar is Also Off in a Power Outage

PG&E is shutting off power to 800,000 Californians today and tomorrow. More than 1 million California homes are already soaking up sunshine with solar panels to generate electricity. Next year, that number will surge as new building standards take effect requiring all new homes permitted after Jan. 1 to have solar photovoltaic systems.

More than 868,000 California homes have solar panels that are interconnected to the state’s power grid, with a total generating capacity of almost 4.8 million kilowatts. Those solar panels connected to the grid will also be shut off if they are in areas where PG&E is cutting off power. Those homes will only have power if they have battery backup like the Tesla Powerwall or a gas generator.

California has 10-11 million homes.

Why Solar is Out in a Power Outage

There are two reasons that ordinary grid-tied solar will not work during a grid failure. There is a technical reason and also for safety and regulations.

The electronics that control a solar energy system constantly adjust voltage and current to keep the panels operating efficiently as the sunlight changes. The system produces quantities of power that are not dependent on how much your house is actually using in a given moment. In a grid-connected system, any excess power is put back onto the grid for others to use, and your utility credits you on your bill for that power.

During a power outage, the power utility sends out repair crews to find and fix the points of failure. Linemen and women will be jeopardized if there is a local power generator (like a solar array) leaking power onto the grid lines. Solar arrays must automatically shut down per utility regulations.

New inverters with a secure power supply (SPS) feature allow connection to an external socket outlet. They provide up to 1,500W of daytime power when the sun is shining and the array is generating sufficient power in the event of a grid outage.

A battery backup is usually needed to provide power in an outage. This can increase costs by many thousands of dollars.

SOURCES- Tesla, CALSSA, Third Sun Solar
Written By Brian Wang,

54 thoughts on “Rooftop Solar is Also Off in a Power Outage”

  1. I understand CA is shutting down a nuclear power station
    that has been chugging away quietly for decades, generating
    base load electricity.
    This one power station creates as much electricity as all of CA’s
    wind turbines and solar panels put together.
    No, CA isn’t a third world state, but like a lot of indicators, it’s
    heading that way.

  2. The PG&I leadership should have told, in advance, “line X and Y will be shut off by <date> if we have no permission to cut trees and branches to keep the line and the environment safe”. Power will resume only when we have done the proper maintenance.

  3. Sacramento prevents the necessary cleanup that would make the state safer from wildfire. Environmental regulations that benefit no one endanger both populated and unpopulated areas.

  4. No, that’s not what they are saying.

    They are saying the power company will not supply electricity to you if their electricity grid is shut down.

    Exactly the same as in Australia.

  5. I’ve lived in other parts of the country and I have lived in California. California is light years ahead of most states. Maybe you live in Fresno, Victorville? Those areas are pretty bad but most of the state is far beyond anything in the rest of the nation.

  6. So you telling me in America, a power company will not provide electricity to you if you have a network connected solar panel in your home? ……imagine this happens in Australia , there will be riots.

  7. That is correct, with better leadership there would not be a government monopoly grid owner that cannot keep trees from falling on their power lines. It is really very simple; you go out and cut down the trees that are too close and too tall and you maintain your power poles. It works everywhere else but apparently in California it is no longer possible.

  8. Well …. when a school kid with Aspergers is propelled to Nobel Prize candidacy because of her virtue (without attendant life-work), it clearly is the case that sentimentality has overtaken achievement. Greta is the Steven Hawking of environmentalism. Now … if only the sputtering socialists could find a suitably heroic survivor of abortion… nah, that’ll never happen.

    Just Saying,
    GoatGuy ✓

  9. Well, I was going by what he’d related to me during a disgusted rant. *Maybe* the solar power salesman didn’t realize he was an electrical engineer, and fed him the short form for idiots.

    I’ll ask him about that.

    He doesn’t HAVE HVAC, so far as I know. Lives in Ventura, apparently you’d fire it up too rarely to bother with.

  10. Most of America doesn’t have a significant problem with power outages, or homeless people pooping on the streets. Though the paper straw madness does seem to be metastasizing.

  11. In the very large building I and an engineer are designing, I included 8 battery backup rooms with Tesla walls on every floor (the floors are 250′ deep so losing that interior space for battery rooms is no great space hit). This will all be subject to much refinement of course, but because of the building’s unique location over the East River in NYC, FAA regulations prohibit it from ever going dark, even in a city wide blackout.
    We will need much more skilled energy usage analysis, but there are 5 off-grid energy sources so far. Fly-through video here:
    and energy slide from the main presentation below:

  12. Agree here the cheapest way to use residential solar is just to produce enough to cover your use during daytime.
    Use line power to deliver the rest.
    System is not designed to run on its own as you would usually not produce enough to power your house and system is not set up to handle this.
    To run off the grind you need an more advanced system who tend to includes batteries. Solar systems for off the grind cabins are pretty old.

  13. Peak power 4,8 GW is convention 4,8 million kilo….

    But never had all solar panels in California get max power.

    I wonder what max registered is, 3GW?

    UAE will have 5,4GW all hour in up to 80 years for 12 billion dollar

    That price is just for the the four nuclear power plant not all other that ad price up to 20,4 billion.

    But in few year much cheaper nuclear will com out on the market.

    The best will alternate between production of hydrogen and electricity.

    Hydrogen with CO2 will create synthetic fuel that i modern engines have cleaner exhaust than the air they take in.

    Solar panels, wind and battery cars is just an example on how stupid people in California are.

    If they just know basic physic they should have known that California is the state in US that contribute most per capita to global warming.

    CO2-treat is scientific rejected, but to convert desert to fores is not.

    That´s why no ice age theory have changed greenhouse effect but all changed temperatures differences.

    Have you get true college?

    Then you understand how average temperature increase with 22C with the same out radiated energy if -80C and +50C get same temperature.


  14. WTF is wrong with these people?
    However, it does show that even in sunny Cal, there is no good means (currently) of storing electricity for 24 hours. I know Australia is in love with hydropower storage and tesla batteries, but they hit a drought and ?

  15. I think it is more sinister than you think. I run on the assumption that if it were actually a good idea you wouldn’t need to use violence to force it, the free market will figure it out. From that angle I find it very easy to see the corporate profit motives in literally every law.

  16. What, you don’t think the electric utility lobby had anything to do with that regulation? Get real. There definitely was some dirty dealings behind closed doors. Before I got my system put in, I submitted my monthly average electrical usage. Solar City wouldn’t put in a big enough system to match my actual usage. That forces me to still be tied to and rely on SCE for a small amount of power, worse in the summer.

  17. Goat, are you sure one only needs to emulate a 60 Hz signal to fool the inverter? I was told the solar inverter needs see a load as well to ‘turn on’. While I did sign a statement promising not to modify my installed system, it would be trivial to add a disconnect switch for grid isolation and inject a 60 Hz signal.

  18. Safety is the “we can explain this in 10 seconds or less to a mass media audience” thing.

    The real issue is a bit more complex as Goat and I try to describe elsewhere in this thread.

    Basically, the technology of the cheap solar installs can’t work without a grid connection working.

  19. Nah, that still doesn’t work.

    Solar panels hooked up to a standard inverter just isn’t able to produce the required power to feed into your house. The solar panel output is too variable (cloud goes over? Output collapses in seconds and then shoots right up just as fast. Aeroplane goes over? 50 times as fast.) and the load in the home is too variable too.

    There are a couple of ways to get around this.

    Cheap option (used by 95% of installs). Hook it up to an “infinitely big” grid (close enough to infinite as far as your little solar panel is concerned). Then this stabilized everything and a little bit of clever metering plus a little bit of clever legislation get’s the balancing for free (where free means you don’t pay for it, the cost is spread out over all the grid customers).
    BUT this means you have to shut everything down when the grid is down.

    OR, you can come up with a system that can balance itself. But this means both a more expensive inverter and a battery bank. Much more expensive.

    This isn’t a California thing, this is a current state of technology thing. The same applies everywhere in the world.

  20. You’d think there would be a sane HEMS and HEMS interoperability standard by now in the IoT age to deal exactly with mixed storage and power sources (and availability of said sources) and outlet prioritization , but…

  21. People who can’t tolerate an outage usually get a generator. Batteries are still too expensive for most people. But that might change in the coming years.

  22. Everyone just assumed it took money and that’s the reason no maintenance was done, all it takes is better leadership…go figure.

  23. With better leadership, there would have been better planning, maintenance, and operation of the power grid so it could operate safely during heavy winds and dry conditions.

  24. Exactly, RedCar.
    Not sure where in America has this evolved, perfect economy with healthy, wealthy and wise citizens.

  25. People go solar for cost savings, saving the environment etc.
    If the goal is uninterruptible power, there are no laws against it in California. You just have to go about it a little differently; different equipment/costs. That does not make California freakishly screwed up. Not sure what state you are in but that just sounds like common sense.

  26. Safety is a fine excuse for doing something, if that something is a reasonable way to achieve safety.

    Not otherwise.

  27. You can get grid tie inverters that have a stand alone mode. Solaredge has a line of them called StorEdge.

  28. California doesn’t require that your own power be cut, absolutely.  

    What it rightly requires is that the consumer-who-knows-nothing-about-how-electricity-works will have a system that doesn’t export power down-grid when the grid shuts down.  

    The cheapest and most straight-forward is an inverter-monitor that just shuts down A/C as soon as a high-load condition exists. And stay down as long as A/C isn’t present on the 240 VAC side. Makes good sense, as long as one doesn’t have batteries and an expectation of off-grid continued service.

    THE PROBLEM for the more sophisticated case (batteries, inverter, la, la, la) is that realistically one’s inverter isn’t up to the job of powering everything in a house, as the grid is. You know, HVAC, washer, dishwasher, dryer, blow-dryers, all the dâhmned TVs, oven, InstantPot, microwave(s), toaster, sewing machines, iron, outdoor lights, refrigerators, deep freezers, and all the rest of the invisible kit. 

    We had 60 amp service, and regularly blew the ‘main breaker’ when all that shît was working.

    Our inverter is only rated at 8,000 W, which at 240 V is 35 amps or so. See what I mean?

    So, I’m designing a more robust way to deal with this AND still be off-grid-survivable. It’ll take a 2nd interior breaker panel for just the critical stuff. And batteries. And very smart battery charger.

    Just Saying,
    GoatGuy ✓

  29. I am in Southern California, and had solar panels installed 6 years ago. I’m an electrical engineer, so I looked into the various models of inverters. I found an SMA Sunny Boy model with a feture called Secure Power Supply and had the solar installer put that one in, I think it was one or two hundred dollar difference.

    If the grid power goes off, the solar panel power is also automatically shut off for safety. There is a separate outlet box next to the inverter that can be manually switched on, which also disconnects the inverter from the grid, so no safety hazard for utility workers.

    There isn’t enough power to run a refrigerator, I think it’s 10 amps max, but enough to charge cellphones and run computers. I got this feature more for a major earthquake that might cause long term power outages. I can use daytime power for pumping water from my neighbor’s swimming pool ;>)

    It would be great to have a Tesla Powerwall, but that’s out of my budget. The inverter upgrade was a very affordable “insurance policy”.

  30. Right. Now, in principle, (In practice, in most states!) you could have a shut off where the grid connects, and during an outage instead of trying to power all your neighbors, you’d just power your own home.

  31. We JUST installed solar. 7.2 kW system ‘technically’, tho’ with this, that and the other thing, it never produces more than 5.6 kW A/C-to-the-grid. 

    The wiring of the thing tho’ is why its output MUST be cut when power from the pole is down. Here’s a diagram. 

    As you can see, no batteries, so the 60 Hz A/C signal comes from the grid. When the grid ‘fails’ or is shut down, the load from all our neighbors is what our inverter is trying to ‘push against’. Too much current, so it instantly shuts down.  And stays down until 60 Hz arrives at its output (input monitoring). The PV power is lost.  

    Were we to have a battery, the type-and-kind of inverter substantially changes. It is in charge of synthesizing our domestic power use, and keeping the battery charged from a combination of PV produced power, and when substantially low on kilowatt hours, even from using the grid to charge the thing up. The algorithm has to be pretty smart though… since ‘tomorrow’s PV’ generation is unknown, and needs to be internally utilized to the fullest, to most effectively defer or sidestep PG&E charges. 

    I’m waiting for the hi-capacity batteries to become cheaper, and for us to get a high-range E-Car to maximize the internal PV storage and utilization. 

    Just Saying,
    GoatGuy ✓

  32. I’ve lived in CA my whole life and it is definitely trending towards 3rd world status.

    Poverty, unaffordable everything, poor roads, poor education, reduced education hours (half days are a weekly occurrence), homelessness, rampant drug addiction, mental health issues, unreliable power grid, etc.

  33. Most voters don’t pay attention to this sort of thing unless/until it affects them. I’d be surprised if there wasn’t a bill to allow permits for inspected systems to keep running in an outage in California soon-ish.

  34. It is a normal feature. California simply mandates that you go one step further, and cut off the panels.

    No, it’s not rational, California is just governed by morons.

  35. Yes, that’s what I’m saying: From a technical standpoint, all you need is a cutoff switch to disconnect the house from the distribution system, so that you’re not feeding juice into lines the linemen expect to be dead.

    But from a legal standpoint, what California mandates is actually that your solar power system not deliver to your house during an outage, even if your house is disconnected from the grid. You can still run off batteries, if you have them, but the panels get automatically disconnected.

    Under California building codes, if grid hookup is available, you MUST be connected. It isn’t optional.

    It’s a nutty state.

  36. Surprised to read this. I thought it was a feature in modern solar inverters to detect when the grid has shut off, and thus disconnect from the grid with a relay to protect power workers. Obviously, if you’re a lineman working on a grid that you think is down, you don’t want some homeowner back-feeding you juice when you’re not expecting it. I worked for a company that made industrial-scale solar panel inverters and our equipment had this safety feature.

  37. its hilarious watching the state descend into a 3rd world shithole.. sad but whats to be expected with the leadership they elected

  38. you cannot send current on somebody’s else network if they tell not to. It is a hazard. If the solar had an independent in-house switch it could have been used. but then feed-in is a different story

  39. Yeah, my brother in California looked into solar, and gave up on the idea when he found out it was mandated to cut off your power if the utility power went off. California is one freakishly screwed up state.

    And, yes, I know they have an excuse. It’s a bad excuse.

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