Rooftop solar panels overloading electricity grid

[Chris_]

Rooftop solar panels overloading electricity grid

THE runaway take-up of rooftop solar panels is undermining the quality of electricity supplies, feeding so much power back into the network that it is stressing the system and causing voltage rises that could damage household devices such as computers and televisions.

Power distribution lines and home wiring were designed for electricity to flow from power stations to appliances, but households with solar panels do the reverse of this.

One of Australia's biggest electricity network providers, Ausgrid, yesterday warned that there was a "significant likelihood" that costs would have to rise because of the impact of the solar photovoltaic cells.

The Australian

Everybody Panic.

[FreeBorn]

 

[Chris_]

Mr Hart, who owns EcoSouth Solar Electricity, said solar systems "drop out for a few minutes" when voltages get too high, a phenomenon known as "tripping out".

"Then they try to come online again and it pushes the voltage up again and it's very wearing," he said. "That's the problem with having too much solar in an area where the local authority hasn't got enough wires or copper in the street to hold the voltage down."

Uh huh.

[CG6468]

Well, something or someone is tripping. Out.

[docstew]

Well, something or someone is tripping. Out.

You are tripping out, man.

[thundley4]

I didn't know wires would only conduct electricity one way.  There would have to be one heck of a lot of solar panels to even make a difference.

[LC EFA]

I didn't know wires would only conduct electricity one way.  There would have to be one heck of a lot of solar panels to even make a difference.

There are a rather large number of them out there actually. In part due to the massive government subsidy given to purchase and install them , and in part due to the over parity price paid for the electricity they produce (also derived from government subsidy).

Not that this has any bearing on "overloading the grid" , which sounds a lot like bull plop to me.

I do wonder what will happen in 12-24 months when the first real run of inverter and control system faults start happening though.

[DefiantSix]

I didn't know wires would only conduct electricity one way.  There would have to be one heck of a lot of solar panels to even make a difference.

Whatever you do, DO NOT tell these idiots about the concept of alternating current.  Else, we'll find 'em at the base of a power pole one morning, looking something like this.  (Warning: link not for small children or the faint of heart.)

[NHSparky]

(sigh)...okay, here we go again...

Unless you live on a spur/line which has pretty much EVERYONE on solar, and even then only during the peak generation, grid instability is not gonna be an issue.

However, when you do have inverters feeding the local loads with no real protective devices to speak of, IF (BIG IF) they get to the point of being able to generate more power than the main line can deliver, then you'll run into issues with reactive load causing voltage and stability issues, reverse powering the line and possibly transformers at the distribution level.

The worst issue when dealing with generators or other sources of power is backfeeding the line.  Let's face it--if you've got enough solar photovoltaic generation capability, you can afford a reverse power disconnect that divorces you from the grid if you try to backfeed it.  And if you have that kind of money and generation power, you need to (and should consider) divorcing from the grid entirely.

But yeah, dropping the load on the bulk transmission lines and transformers?  Not because of a few rooftop cells here and there.  As previously stated, lines aren't the issue so much as lack of regulation of the reactive load.

[Chris_]

(sigh)...okay, here we go again...he worst issue when dealing with generators or other sources of power is backfeeding the line.  Let's face it--if you've got enough solar photovoltaic generation capability, you can afford a reverse power disconnect that divorces you from the grid if you try to backfeed it.  And if you have that kind of money and generation power, you need to (and should consider) divorcing from the grid entirely.

I wonder if a lot of these people installing PV kits in their homes are more interested in the "free money" from the power company than actually getting off the grid.

[DumbAss Tanker]

Unlikely to be a problem in the US.  Our subsidy programs aren't as extreme and Solyndra has kind of poisoned the well to add to them for the time being, plus damned little of the well-populated parts of the US get enough unobstructed sun (Between cloudiness in the Southeast and air pollution in Californistan) for it to ever be the kind of issue it would be down under.

[Wineslob]

Sparky, do the line transformers work in reverse? I'm trying to figure out how household current can flow backwards through a stepdown transformer.     

[NHSparky]

Sparky, do the line transformers work in reverse? I'm trying to figure out how household current can flow backwards through a stepdown transformer.     

In theory, any transformer could be run backwards, but you get to a point where that becomes problematic, particularly when dealing with protective relaying. 

For example, a lot of relays on transmission, sub-trans, and even transformers do rely upon directional relays or measuring phasors of each of the three phases.  If power is flowing the "wrong" way, it might be outside the zone of protection and never trip.

But as I said earlier, based on the very limited information regarding voltage instabilities and tripping of the lines, it sounds like they're having issue with reactive load rather than supply/demand.

[Wineslob]

So I take it, they might be creating too many odd harmonics on the lines? Or, as some say, "dirty electricity"?

I just find it hard to swallow the whole idea that solar can feed back into a high voltage system.

[TVDOC]

So I take it, they might be creating too many odd harmonics on the lines? Or, as some say, "dirty electricity"?

I just find it hard to swallow the whole idea that solar can feed back into a high voltage system.

ANY generating source (of the correct voltage) can feed back into the grid.  Although the base output of a solar array is low voltage DC, the panels feed an inverter, that converts the output to (typically) 120/240 VAC.

When I rebuilt my companies Indianapolis TV station, I installed a 750 K, 480 V (three phase) diesel generator to power the station during outages.  The local utility gave me a substantially lower rate if I agreed to run the generator backfeeding their system in times when their load was becoming close to capacity.  As a part of that agreement, the utility installed different relays, patched into my remote start system,  and also provided  monitoring capability at my generation site.

Since the power bills for a UHF television station can easily run $15,000 to $20,000 per month, the savings offered by the utility paid for the generator in about five years......a good business decision.

doc

[Wineslob]

As a part of that agreement, the utility installed different relays, patched into my remote start system,  and also provided  monitoring capability at my generation site.

This what I was thinking of. Woulden't you need this kind of installed system to "feed back"? Not saying you can't do it, but I don't know that the average homeowner will have this set up.

[NHSparky]

So I take it, they might be creating too many odd harmonics on the lines? Or, as some say, "dirty electricity"?

I just find it hard to swallow the whole idea that solar can feed back into a high voltage system.

Doc is right.  ANY source can potentially "backfeed" a system.  And if you don't have good coordination/relaying schemes between your sources, you're just asking for trouble.

God help you if you're the idiot who hooks up his generator to his household panel without a transfer switch or opening/disconnecting the mains.  Linemen or civilians can still get killed from downed wires because some dipshit was lazy and didn't "island" his home from the utility.  Even a generator putting out 120/240 can go through the pole transformers and step it up to 4160, 12KV, or more.  Granted, your basic home generator probably won't like it much, but it'll TRY--right up to the point it craps itself.

As far as harmonic distortion goes, Doc or someone who deals with solar can probably answer better than I, but I would think it depends on the quality of your inverter.  As for me, if I were to put a solar panel on my roof (not likely in NH) I'd be more concerned about the specs on the inverter and what methods I have of quickly divorcing from the grid if need be.

Finally, unless these folks are also dealing with storage systems (read: batteries), putting something that large on for a residential or even small business to cover all their loads simply doesn't make a whole lot of sense.  Where I'd be tempted to do something like that is in places like California where they have a "tiered" system of electrical charges, the fourth and fifth tiers topping out at over 30 cents per KwH.  I'd rather put up a 10KW photovoltaic to run my peak loads during the day instead of paying SDG&E or SCE several hundred a month to run my AC in the summertime.

Otherwise, solar is pretty much a waste from a bulk generation standpoint unless you're chasing tax breaks.

Most homeowners aren't going to have PV systems large enough to do even the majority of their home loads, especially in summer/winter, let alone overcome home demand and supply the grid.

[Rugnuts]

Whatever you do, DO NOT tell these idiots about the concept of alternating current.  Else, we'll find 'em at the base of a power pole one morning, looking something like this.  (Warning: link not for small children or the faint of heart.)

thats not the detroit i know

they still have their shoes

[TVDOC]

This what I was thinking of. Woulden't you need this kind of installed system to "feed back"? Not saying you can't do it, but I don't know that the average homeowner will have this set up.

It depends on the sophistication of the system, and the knowledge of the designer/installer.  As Sparky mentioned here:

As far as harmonic distortion goes, Doc or someone who deals with solar can probably answer better than I, but I would think it depends on the quality of your inverter.  As for me, if I were to put a solar panel on my roof (not likely in NH) I'd be more concerned about the specs on the inverter and what methods I have of quickly divorcing from the grid if need be.

Although I am not really a solar fan, however I understand the concepts, and have read the specs on some of the equipment........and exactly as Sparky says, the key is the quality of the inverter........most of them are garbage, and generate either a square, sawtooth, or trapeziodal waveform.....not a pure sine wave.  Not only is this piss-poor waveform hard on all kinds of household electrical equipment, it's impossible to syncronize with the mains.  A "pure sine-wave" inverter is damn expensive, and not covered by any of the solar incentives like tax breaks.  Most of what's out there in residental use is fine for running lightbulbs and resistive loads.....but not much else......forget about backfeeding the grid.

In order to "backfeed" your equipment needs not only to produce a pure,regulated sine wave AC voltage, but have the capability to vary the frequency (and phase angle) of that sine wave to "exactly match" that of the mains.  Otherwise it's useless, and causes the utility more problems than it's worth.


doc

[Chris_]

750 K, 480 V (three phase) diesel generator

Speaking of diesel generators...



This is our newest one.



...and next to a 6.7 liter Dodge Ram engine.

[TVDOC]

^ Err.....that's just the engine, where's the rest of it??

BTW, that big engine looks very similiar to the twin-turbo, V-16 Cummins that powered my 850K when I installed it here in KC (It was an Onan).......1700 hp.......that sucker would bark, even with hospital mufflers, and suck up some serious diesel fuel under full load.......

doc

[Chris_]

Details, details.

[NHSparky]

I'll have to snap a few pics of the DG's we have at the plant, then.

[vesta111]

Thank you, we just bought a used generator and have been round and round about this.

My fear is that if not installed correctly some person repairing downed power lines will get fried. This switch you mentioned sounds expensive, does it need a Master Electrician to install it ????

All we really need is for the gas furnice to run, I can by pass the electronic gizmo to the  gas stove and if food is lost in freezer and refrige, so be it.

Main concern here is for the safety of others and naturally our own,  don't want the darn thing to blow up and burn down the house.

First thing I can think of is can we take it to a repair shop and have them check it out-----the darn thing is about 15 years old and the pull start was too much for the seller to handle.  Will the cost be more to have it checked out then a few days in a motel??   Only 1 shelter that will take pets within 25 miles of us.

Second is the cost to hire an electrician to hook it up, do I need to ask to see some kind of license or bonding to insure they are capable to do the job????

Third question is, what ever happend to Whale Oil lamps and how did folks before they received electricity survive??

BTW the original sales receipt came with the generater, back then the cost was $1600 bought on sale for $900. We paid $200 for the sucker.   We trust the seller.

Any ideas??????

[NHSparky]

This switch you mentioned sounds expensive, does it need a Master Electrician to install it ????

A transfer switch is actually rather IN-expensive compared to having an electrician come out and disconnect/reconnect your mains.



The one pictured above is very similar to the one I have at home.  Very easy to install.  If you have a 240-volt load such as your well pump, simply use the included bar to tie two switches together.  You can get a reliable one for $300-400.  While that SOUNDS expensive, an electrician will charge $60/hour (min. 2 hours) to disconnect/reconnect your main.

And no, anyone with a basic knowledge of electricity and basic handyman skills can mount and wire this thing pretty easily.