Approval free alternate energy tie ins ?? 2

[2dye4]

Why can't you go to your home improvement store and buy an alt energy system and use it to offset your homes power usage.

The utilities don't like it that's why.
The main reason cited is line worker safety from back feeding the grid. If that is the only drawback I have the solution.

Why cannot the utility place a Power line carrier signal on their lines that travel through the grid and find their way to the utility intertie inverter that refuses to supply power without seeing it.

Presto. If a grid source breaks the alt sources go down automatically as a result of loss of the carrier signal.

This should not be a serious technological problem and it would allow off the shelf purchases of Alt energy systems to be purchased and tied into the grid for lowering utility bills.

When the consumer can see it and touch it and take it home and use it there would be much higher uptake of alt energy systems and the savings would mount silently.

Any reason this wouldn't work.

 

[stevenal]

Put yourself in the lineman's shoes. Would you be willing to risk your life on the bet that this un-seen, out of reach device was not tampered with and properly disconnected upon loss of the grid? Anti-islanding inverters are already available.

 

[itsmoked]

Any reason this wouldn't work.

Yes, because utilities completely despise user backfeeding. They only allow it because it is mandated by govt and for PR. They certainly won't do anything to help anyone do this, such as your solution.

On your solution, it would be very expensive as the carrier frequency you suggest won't reliably pass thru transformers.

Also, it is completely unnecessary for the task. It is easy to prevent the scenario of back feeding using other methods. One company had an outstanding solution that people started flocking to. It was a completely safe way for you to hook a solar panel to this wall-wart and plug the wall wart into any outlet. It would only close circuit to the power if the power was present. If the power went away it would instantly drop out. This essentially allowed anyone to start at any size with reducing their power bills. They didn't have to drop $30 or $40K. That company was bought by Xantrex and suddenly that 'solution' disappeared over night. It was very sad.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[DRWeig]

Quite sad, Keith!

I never did anything at the residential level, but there sure ought to be a simple device like you described.

On the bigger cogeneration sites, the utility (usually TVA in my area) always required us to design-in protection plus a remote kill under their control. Since most of the projects involved recovering waste heat, I was able to design around small turbines and induction machines -- inherently safe since they need utility power for a field.

I could make a market for those wall-wart things you described, I bet!

Good on ya,

Goober Dave

 

[2dye4]

smoked

You are right they hate backfeeding. But they have no right to a monopoly.
As far as the carrier it might be selectable to pass transformers and not be absorbed by loads.

My point is that a legally mandated standard is needed in order to eliminate the bureaucratic wall of red tape erected to prevent uptake.

stevenal
I assure you my concern would be a system as full proof as possible, and this seems to be not beyond the realm of possibility for the engineering community.


The beauty is that a standard adopted into federal law would preclude the need to submit to utility badgering and inverter manufacturers would have a standard to manufacture to. The elimination of the communication and confusion would be a boon to alt energy.

If a carrier can't do it, how else could it be done with 100% certainty.

RF receivers in the inverters, receiving utility narrowband signals ?????

The key to the compromise is giving the utilities a remote kill switch. They having the control would have a hard time making the case that it is dangerous.

 

[jghrist]

Part of the kWh utility charge pays to build the lines and equipment that get power to your house. If you generate you own kWh when you can, but still expect to have the utility available when you can't, I'll have to pay for part of the lines to your house as part of my utility charges. Where's the justice in that?

 

[stevenal]

The lineman is only safe after he has visibly isolated all sources, locked or tagged them open, tested for potential, and grounded the lines in question. The inaccessible nverter has no place in any of these steps.

Anti-islanding is accomplished by inverters that attempt to run fast. If not held back by strong grid, they will disconnect when they sense the resulting over frequency condition. Like any electrical device, they are built and tested to a listing agency standard such as UL.

I think you are trying to fix a problem that does not exist.

jghrist,

Good argument for implementing a basic service charge. Same argument applies to vacation homes. Little energy used, but they want it there when they want it.

 

[busbar]

 
Off the top of may head, some applicable standards for “grid tie” PV installations are IEEE 929, UL 1741 and NEC 590. It’s a fairly popular practice in the west. See

http://www.livesolar.net

There’s ten of them currently listed.

Don’t forget there’s still a permitting and inspection process to go through. All the ones I’ve seen have 600V visible-blade heavy-duty lockable disconnect switches accessible to utility workers 24/7 for isolating either the AC or DC side, {local-utility preference I guess} regardless of the inverter(s) rating.

One other point—lineworkers are blatantly lazy/stupid for not using personal-protective grounding in their clearance process.

 

[boBK7IQ]

Itsmoked said:

>>That company was bought by Xantrex and suddenly that 'solution' disappeared over night.

Which unit was that, Keith ?

boB

 

[rmw]

[qoute 2dye4] You are right they hate backfeeding. But they have no right to a monopoly. [/quote] Au contraire-they do have a right to a monopoly. It is called a franchise and it is given to them by the governmental jurisdiction. Their right to a monopoly also brings the responsibility to have power available any time you turn a switch on.

How long do you think your local grocer would permit it if you began to come in and put your merchandise on his shelf? In effect anyone who puts power on the grid other than themselves is competing with the profits they make on their own generation although this is changing with deregulation and diversification of generation companies from T&D companies.

The safety aspect however is still the most important for anyone connected to or working on the grid.

rmw

 

[alehman]

Keith - that wasn't Trace Engineering was it?

The state of Missouri recently passed a law requiring $100,000 of liability insurance for small grid-tie systems. According to a article in today's Kansas City Star, the problem with that is that there are no insurance companies that can provide this coverage.

 

[itsmoked]

Well.. It was quite a while ago.. Yes, I think it was Trace.

Yes, I'm sure it was.

It was a micro grid-tie. A fellow EE and I were both considering purchasing them. He was a little more motivated than I. About a week later he decided to buy his. He goes to the Trace site and discovers it's gone and the company has been changed to Xantrex. Everything is the same except that one single product is gone. He promptly called them and was told, "We are not producing that product any longer". They were very curt about it and would provide absolutely no comment about it. They seemed a bit angry even.

As far as we could tell it wasn't just phased out it was 'stamped out' like a burning ember.

We started thinking Trace was purchased by some shady entity for the sole purpose of buying the rights of that device and crushing it. Thoughts of dark conspiracies, trench coats, hit men, lobbyists, and lawyers came to mind.

I could imagine a big power company buying out Trace from petty cash to nip a new, bad-for-them, technology.

But who knows. It could have been something like a nasty letter from a power company.

I would really like one as I always creep into the third tier where my power starts costing 26 cents/kWhr. Being able to use a few solar panels to just back out that 3rd tier stuff would be great and a good return on my solar dollars.

Oh well.




Keith Cress
kcress -

http://www.flaminsystems.com

 

[boBK7IQ]

>>e started thinking Trace was purchased by some shady entity for the sole purpose of buying the rights of that device and crushing it. Thoughts of dark conspiracies, trench coats, hit men, lobbyists, and lawyers came to mind.

Keith,
Your are very close here... That micro grid tie unit was the OK4U 125 Watt or so unit, made in Europe (still is I believe) The problem was that it wasn't UL1741 listed so they had to stop selling them in the USA. This one wasn't Xantrex' fault, but still, you weren't too far off in many ways !

I worked at Trace and through that transition for another year. Xantrex has now been bought by Schneider Electric.
The timing was just a coincidence in the case of that particular inverter.

boB

 

[itsmoked]

That's very interesting!!

I was hoping someone would know what the actual facts were!

Thanks for clearing that up boB.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[alehman]

Interesting. I wonder how Missouri could justify the $100K insurance requirement for these micro systems, assuming others become available. I really have trouble seeing how a 125W unit is going to be a threat to anybody. I wouldn't be surprised if our insurance legislation wasn't sponsored by local utilities.

26cents?? Holy cow!

 

[jraef]

Am I just thick, or is there a basic problem with the initial statement that has been over looked?

... If a grid source breaks the alt sources go down automatically as a result of loss of the carrier signal.

So in this scenario, what would be the purpose of even having an alternate source if BOTH go down if the grid goes down? Makes no sense to me.

Be that as it may, line carrier signals can be made to work, in fact we will soon be seeing that technology in use with a lot of the major utilities for TOU billing programs. But as stated earlier, would YOU as a lineman want to be stripping a HV cable at the moment when the microprocessor in someone's alt energy system decides to reboot and takes a second or so to figure out that the carrier signal is not there? I would not. I want an air gap, preferably one that I can see and install my lock onto.

Besides, what's the problem with installing an isolation switch anyway? I would think that if you are so financially strapped so as to not want to go through the necessary approval steps to connect to a grid safely, then you probably will not be able to afford proper maintenance of your alt energy system eithersystem, thereby disqualifying you to be connected to the grid in the first place.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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[alehman]

I think grid-tie systems are commonly installed for financial or environmental "feel-good" reasons rather than specifically as a backup power supply. Normally they operate in parallel as "net metering". UL-1741 listed grid-tie inverters sense for loss of utility source and disconnect immediately. The relaying in these units does not require any special signals from the utility. They will continue to supply the load if possible while disconnected. I think most utilities require an exterior manual isolation switch as well.

 

[cranky108]

How many people are aware of how many ways a grid tie system can be screwed up. That's the reason we inspect each and every one. Also we are mandated to produce X amound of solar energy, which we purchase from our customers, and many of them want to be paid for it. Just like we want credit for not having to pay state fees.
So the arrangment is, if you want to be paid for alternate energy production, you let us meter it, inspect it, and be able to disconnect it when needed.

In general grid tie inverters work, as do induction motors, but we have to know they don't produce to much noise that you nebors will complain about.

 

[2dye4]

rmw,jghrist
You have touched on the exact issue. The utilities do not want grid tie sources for some economic reasons.

However if we adopt this thinking as legitimate then there is not alternative energy industry at all, as it is counter to utility interest. These concepts would condemn even alt sources that augment utility purchased power.

I cannot believe that at a time when there is much whining about all the new generation capacity we are going to need soon that allowing alt sources is a bad idea.

cranky108
If grid tie systems were limited in power level i find it hard to imagine any issue that could not be handled by Standards for design and installation.

My central idea is that a standard design and standard installation should allow installations without inspection or even approval by the utility.

To require anything else is to doom alternative energy for the individual and throw out the possibility of significant power augmentation by homeowner installed systems.

 

[cranky108]

That's not true, as we do have many incentives for solar energy, including net metering.
The biggest setback for solar is the 20 year payback, for equipment that is expected to last only 15 years.

Truthfully, it's more cost effective to heat water with solar, then generate electricty.

If you want to talk about wind, no we don't want more than is mandated, because it requires us to rase our costs to our other customers.

If you want to connect to our grid without telling us, the meter won't turn backwords. You won't be paid for the electricty, and a electrical inspector from the area will be sent to your home (NEC requirments adopted by the state).