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Post by Deleted on Feb 15, 2018 19:59:18 GMT
Light Bulb Goes On
Boomer has the solution: "As for power from a solar install being fed back into the grid, wouldn't it have a failsafe to cut off the feed if the power grid went down?"
That would take care of the danger.
If the systems had a failsafe why are we told about their danger of putting voltage oin downed lines?
But if they don't already have that failsafe, why don't they?
Once again the ALPB may need to call someone on the telephone and straighten things out.
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Post by Admin on Feb 16, 2018 3:02:48 GMT
Most systems which back-feed the grid will not back-feed if commercial power is not detected. These systems us a synchronous inverter which uses a zero crossing detector to synchronize the inverter output to the line power. When it loses that sync from the line power it ceases to feed power back into the grid. This link has info regarding this: NO GRID=NO BACK FEED |
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Post by End80 on Feb 16, 2018 8:01:36 GMT
Most systems which back-feed the grid will not back-feed if commercial power is not detected.
That's half true, as it apparently does not apply to "Most Systems".. At least not according to the majority of the news articles reporting about solar in relation to the last few hurricanes hitting Florida. Below are excerpts from just from the first three googled results, but there are pages more saying the same thing. It's all got to do with the 'Florida Power and Light' (FPL) metering guidelines, who have also been heavily criticized for instead of making their installations more hurricane proof by burying power lines and such, they opted to spend the money lobbing millions of dollars towards keeping homeowners from powering their homes with solar.
Here's just a couple excerpts from a vast many reports:
"..Yes. The vast majority of solar systems are what’s known as “grid-tied.” If the power goes out, the photo-voltaic system automatically disconnects. If the grid has no power, the solar system has no power, experts say. Even if the sun is shining, the panels will not generate power... the standard, grid-connected solar system cannot necessarily be counted on to replace the power grid if you are without power after a storm... “If the grid goes down, your solar panels are ‘down’ as well, not providing any electricity to you. If you’re not sure what kind you have, they are probably connected to the grid,” ... If you have a rare off-grid system, complete with a battery back-up, then it would work," -- www.palmbeachpost.com/business/after-hurricane-irma-why-solar-power-can-replace-storm-damaged-grid/mSmLcXjuPFAOWw4GHlYsTI/
"..residents with solar panels actually can use solar power if the grid fails – but only if “they purchase additional equipment to prevent volts of electricity from traveling through power lines and harming unsuspecting neighbors or repair crews.” -- inhabitat.com/florida-residents-prohibited-from-using-solar-energy-after-hurricane-irma/
"..FPL's lobbying wing has fought hard against letting Floridians power their own homes with solar panels. The company spent millions pushing Amendment 1, which would have ultimately made it harder for homeowners to embrace solar technology. Thanks to power-company rules, it's expensive in Florida to simply buy a solar panel and power your individual home with it.
FPL's online rules also say that if the power goes out, your solar-power system must power down along with the rest of the grid if it does not have a set of backup batteries installed along with it..."
-- www.miaminewtimes.com/news/miami-frustrated-with-fpl-after-hurricane-irma-9666311
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Post by Boomer on Feb 16, 2018 18:49:15 GMT
Back-feeding power, a new form of carrier current
Wow, articles on something technical by professional writers, details are sketchy, like when they write on radio things.
I could see when you're dealing with sine waves, you'd want them to be phase locked with the power line frequency. Different sine waves added together cause spikes and unusual wave shapes that would probably react oddly with loads on the line, not to mention circuits in the inverter's output. I know, use GPS frequency sync when you broadcast your 60 hz carrier to the power line..
If the power grid fails, it's hard to see how one house could continue to supply demand current on the line, since all the other houses would immediately draw power from yours. The system could certainly know to shut down with that kind of load, right?
The only danger I can see, as an armchair solarist, is in a limited circumstance where the wires from your house are pulled out at the pole and dragging in the ground on your yard, while your solar is on.
If SpaceX can put up over 4000 satellites for the internet, surely all power line issues with solar systems could be solved.
Boomer
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Post by End80 on Feb 16, 2018 19:46:05 GMT
Back-feeding power, a new form of carrier currentWow, articles on something technical by professional writers, details are sketchy, like when they write on radio things... Boomer Your missing the point the news reports are making.. It's not really a technical problem, it's a power-grab political problem.. Yes, it can be done, but in Florida they make it difficult and expensive for the home owner to take advantage of the benefits of solar. Yes, homeowners can and do have solar systems installed which will work both when the grid is up and when the grid is down, but the cost involved outweighs the savings solar provides - thus takes away the motive for utilizing solar to begin with. By the time those homeowners reach a return on their investment they'll be dead.. There was another big Power Company somewhere - in Texas I think who also played the cards against homeowners going solar. |
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Post by Druid Hills Radio on Feb 16, 2018 20:23:05 GMT
Fortunately FPL isn’t the only game in Florida.
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Post by Admin on Feb 17, 2018 3:35:22 GMT
Apparently, our local City owned power distribution system is OK with solar. I assisted with the installation of a solar system for the local schools.
The Middle Schools each have a 4 kilowatt solar system for students to learn about solar power. The system does not use battery storage. Rather, it simply back-feeds the grid when the sun is shinning. This probably only serves to reduce the schools power cost as I'm sure they consume more than 4 kilowatts when open. But again, these systems serve to show students solar power. And yes, these systems will not back-feed if the commercial power fails.
There are also a couple businesses that have installed wind powered systems. These are small by comparison to most but a start with supplementing their power use.
I have heard stories of power companies that have been granted a fee imposed on anyone employing solar power especially if they go off grid. Their reason? Supplying power is a "community service" and as such it depends upon all who live in the community to help support the system whether they use it or not.
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