grid tie with battery backup

[whythehecknot]

My question is this, can you use a grid tie'd inverter to act as a load diversion when the batteries are topped off and if so how. What I am thinking is to use a charge controller from the batteries to dump power into the inverter that is grid tied. Of course I realize I am going to need another charge controller besides the one running the grid tie inverter should grid power go down. And would the batteries overload a grid tie inverter? Or would it just peak out @ max output when battery run? And if so is there a way to limit that power?
  The system in question is going to be a 5 KW 48V wind turbine feeding eight Trojen L16's, and hopefully putting excess into the grid. Power could then be switched in case of an outage.
  P.S. does anyone have any experience with the XW 6048???

[freejuice]

I use an outback GTFX 3048 for grid tying...it tops off my batteries...I also use the battery power ack  through  teh inverter to a transfer swtich for the circuits I select to use and then the excess goes into the grid

[freejuice]

why the heck,
 I dont have a clue about the xantrex....I'm sure there are many gurus here that do know about them...Chris Olson I believe has one.

 However if you get a "Mate" for an Outback, you can set it for when the batteries dump the excess into the grid..I think the factory default setting is 53 Volts on a 48 volt inverter.
 The outback, will also charge your batteries from the gird should your alternative power source ( solar wind etc) is down.
The grid does NOT discharge your batteries past a low point setting.
I essentially use my inverter to power loads through a transfer switch, these loads I selected because they dont pull too much from the batteries in which the wind turbine can not keep up or  end up having to use the grid to charge the battery bank thru the inverter....so in essence I balance my daily uses to pratically match my daily power generation on the wind generator.
 However, if the wind is putting on a show and pushing some power into the batteries and I'm NOT using the excess power then I do have a bank of resistors to pull the power off the batteries for breif spurts, but in my situation I have things adjusted to where I'm either using the power generated or shoving it back into the grid and not wasting it away in a bank of resistors.....often time when the wind has picked up I will watch my utility meter  and the wind gen at the same time.....as the wind turbine picks up speed my meter's wheel will slow down, and as the wind gen's blades increase speed futher, the meter comes to a complete stop and begins to spin backwards

So in essence, if I wasn't using the inverter for powering loads in my home and the wind was pushing power into an already full battery bank, then my inverter would push a max of 3000 watts ( maybe more on brief surges) into the grid before the resistors would kick in and tap off the excess power....
 If you didnt want to waste any of the power generated on resistors, and if your pockets are deep enough you could essentially add another outback to soak up some of that extra power and shove it into the grid too

[ChrisOlson]

  P.S. does anyone have any experience with the XW 6048???

Yes, the XW6048 will go into "sell mode" and backfeed the grid when the batteries are in float and you have excess RE power available.  The XW6048 is fully grid-interactive, as well as fully off-grid capable, and is configurable to make it do what you want.

I don't know what all this business is with charge controllers dumping power to grid-tied inverters, that you talk about.  That's not how it works.  The XW6048 ties into your 240 volt service and supplies power to your circuits using grid power during normal operation, as well as maintaining the batteries for the event of a grid power outage.  When RE power is available it powers loads using RE power as first priority and grid as second priority.  When RE power exceeds loads, and the batteries are fully charged, it "sells" power to the grid.  When the grid goes dead it switches to battery power and keeps your loads powered up.
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Chris

[whythehecknot]

Thanks guys, both of your responces were exactly what I was wanting to know regarding my question. My comment regarding the use of a charge controller was just me trying to make sense of the whole thing. So does the XW 6048 have a way to deal with excess power if the grid is down and the batts are charged???

[ChrisOlson]

So does the XW 6048 have a way to deal with excess power if the grid is down and the batts are charged???

No, it does not.  You still need a "dump" or diversion load to handle excess power in the absence of a grid connection.  It doesn't have to be anything elaborate - just a voltage sensing controller of some sort that becomes active at the extreme high bank voltage that would never be reached under normal conditions, and that diverts the RE power to a load of some sort to prevent bank over-voltage or inverter kick-out due to over-voltage.

I say it doesn't have to be elaborate because you're not attempting to use it as a charge controller - the XW in "Sell Mode" does that quite well (regulate bank voltage and properly maintain the bank).
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Chris

[whythehecknot]

Hey thanks Chris, this's been a big help as although there are specs out there for the XW it doesnt say a thing as to how the thing gets wired, and Im one of those guys that has to know everthing before I plunk down 4000.00 bones for something.

[ChrisOlson]

I would recommend calling Schneider Electric's Renewable Energy division, if you're interested in a Xantrex, and find out who your closest dealer is.  Go buy the inverter there instead of online.  Then you get hands-on support and make sure you get everything you need.  The inverter is only the base component.  You may or may not need the AC/DC Conduit Box, auto gen start, remote display panel, etc..  The XW has a lot of options that a dealer can help you with in getting the right setup.

Also find out about your utility's policies on grid-tie.  More than likely they will require a lockable disconnect, dual meters, and sometimes a state inspection/certification of your grid-tie setup.  The XW has an option for remote shutdown by utility personnel, that in many cases meets the requirements of the lockable disconnect that is required.

My guess is that after you check with your utility that you'll forget about grid-tie.  I've never seen one that's economically feasible.  And backfeeding the grid without a net metering agreement with your utility opens you up to huge liabilities.  That's the first step before you even start looking at any equipment.
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Chris

[whythehecknot]

Regarding your last comment... I read on this same forum, and even went to a link someone gave of a federal law that pretty much allows grid tie without any special permits. Was there something I missed???

[ChrisOlson]

Regarding your last comment... I read on this same forum, and even went to a link someone gave of a federal law that pretty much allows grid tie without any special permits. Was there something I missed???

Yes, you either missed something or misunderstood.  Federal law requires your utility to allow you to grid-tie an approved system and pay you "average retail" for your power.  However, that doesn't mean they have to make it cheap for you to meet the requirements, or actually pay you money for your power.  Most of them apply a credit to your bill, and you have 12 months to use the credit or you lose it.

Under no circumstances can you grid-tie a system without approval from your utility.  Just what it takes to get their approval can vary by the utility and their policies.  That's why you need to check that aspect out before getting too gung ho about it.  Around here the required state inspection alone costs $1,000.  And the required equipment (lockable disconnect by the utility meter accessible by utility personnel 24 hours a day, plus dual "smart" meters) costs another $2,200.  And the utility charges a flat fee of $40 a month just for the "privilege" of grid-tying your system.

To put this in plain talk, that means that at 15 cents/kWh you have to "sell" about 21,000 kWh just to pay for the upfront costs, and they get the first 267 kWh that you generate every month for free, just to pay for the "fixed charge".
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Chris

[DamonHD]

Note that in the UK, providing that your microgeneration produces no more than 16A per phase, and you use type-approved (G83/1-1) equipment, you cannot be refused connection: you need only notify your supplier and the company that actually runs the wires into your house, ie the DNO, within 24h after the event.  And there is no charge.  Indeed this weekend I hope to be plonking a decent-sized array on my kids' school roof which required no planning permission nor permission to connect nor any payment to anyone other than the people concerned with the installation.  Maybe we got something right this side of the pond, for once!  Less "nanny state" and more "just do it"...  Connection of bigger systems may start to attract charges, and homebrew is definitely not on.

Rgds

Damon

[ChrisOlson]

Damon, my wife is Swedish and I'm well aware of most of Europe being probably 10 years more advanced than the US in energy conservation, use of renewable energy, and technology.  Especially in private homes and public transportation.  In the US people are very wasteful just because they can be, and they think nothing of jumping in a car to drive two blocks to get a gallon of milk at the convenience store instead of walking or riding a bicycle.

So your description of what it takes to install an approved grid-tied system in the UK does not surprise me.  Here in the US, renewable energy and it's use, and $2.50/gallon gas, is buzz words used by politicians, for the most part, that they can spout to get elected.  But if gas was $8 a gallon here like it is in Sweden, I suspect habits would change, and all these "rules" that prevent the practical application of renewable energy sources would also change.  Americans have been spoiled by artificially cheap energy, and when the price of it goes up, it cripples the economy because Americans have designed their whole lifestyle around it.
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Chris

[DamonHD]

I take all those truths to be self-evident... B^>

Rgds

Damon

[freejuice]

I will back up what Chirs is saying....often time I have heard the horror stories of grid tying.
Check before you leap,  your local building codes will be involved and the power company of course. Also if you have neighborhood assocation of some sorts which has restrictions, that would be another hurdle.

I was one of the luckier folks I paid a 45 dollar fee for the building permit.....they came and inspected it...the guy was nice, asked lots of questions about how the system worked, even mentioned he would like to get a solar system too... I told him they are easy to install he said "you did this yourself?" I was thinking uh-oh there might have been a recent law banning self install solar systems....he popped the covers off the junction boxes, breaker panels etc checking my wiring and he signed off on it without any problem.

With the power company I had to sign an interconnection agreement for 100KW or less....paid a 100 dollar fee for the new meter...they inspected it and I was on my way.

I can net meter two ways: I can get paid wholesale rates at about 5-6 cents a Kw or I can do a KW for KW exchange...if produce 1 Kwh and use 2 Kwh then I get a bill at the end of the month for 1 Kwh, after one year if I have any unused credits they simply keep them and the count starts all over again.

I dont have to pay a a monthly " Maintenance fee" to the poco for the system...if they ever started down that road I would convert over to an island system.... I suspect as solar gets cheaper and gains enough momentum to hurt a poco's bottom line...say in the neighborhood of 5-10% I would suspect every utility in the nation would follw others with the "maintenance fee" surcharge

[fabricator]

In MI now when you do a grid tie you get a smart meter, there was just a big blurb in the local fish wrap about the people who are getting smart meters being really pissed off, the old style spinning disc eddy current type meter was not fast enough to catch the entire spike when big loads come on, the new all digital smart meters catch every nano watt, so your bill goes up, in some cases WAY up.
A couple guys said they were gonna jerk the things out and get an old style meter off ebay, the borg said criminal charges would follow such action, you don't mess with the borg if you need grid power, because they can and will just unhook you if they feel like it.

[ghurd]

and $2.50/gallon gas.

But if gas was $8 a gallon here like it is in Sweden, I suspect habits would change, and all these "rules" that prevent the practical application of renewable energy sources would also change.  Americans have been spoiled by artificially cheap energy, and when the price of it goes up, it cripples the economy because Americans have designed their whole lifestyle around it.

Its close to $4/g here.
I gotta get gas where you get gas.  LOL
Guessing that's a typo.

I used to drive 400 miles a week round trip to get to work and back.
Then more than that at work.
Sweden is only 300 miles wide!

"if gas was $8 a gallon here like it is in Sweden" then it would be taxes that caused it.
Arabs don't sell gas to the US cheaper than they do to Sweden.
When they run out of gas, it will (again) be profitable for the US to 'drill' with US labor.

"My grandfather rode a camel, my father rode a camel, I drive a Mercedes, my son drives a Land Rover, his son will drive a Land Rover, but his son will ride a camel".

G-

[fabricator]

We get a small fraction of our oil from Arabs right now most of our oil comes from Canada and south America, you don't see much about it on the news but there is actually an oil boom going on right here in America thanks to Fracking.
The biggest joke being perpetrated on the American people is the subsidies being paid to big oil, they make hundreds of milions per quarter in profit but still they get subsidies for R&D and exploration all because big oil owns the Republican party.

[ChrisOlson]

Its close to $4/g here.
I gotta get gas where you get gas.  LOL
Guessing that's a typo.

No, I was referring to this one politician (can't remember which one it was) that was saying something about if he got elected he'd have gas back to down $2.50 a gallon.  When you hear one say that you can write him off right away.  Because he's already so full of BS it's running out his ears.
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Chris

[DamonHD]

Newt, IIRC.

ALL of the GOP presidential candidates look frightening from this side of the pond, at least to me fairly well over to the right of the political spectrum from an EU point of view.  %-P

Rgds

Damon

[Watt]

Its close to $4/g here.
I gotta get gas where you get gas.  LOL
Guessing that's a typo.

No, I was referring to this one politician (can't remember which one it was) that was saying something about if he got elected he'd have gas back to down $2.50 a gallon.  When you hear one say that you can write him off right away.  Because he's already so full of BS it's running out his ears.
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Chris

Chris, I believe you are right.  I hate to be greedy but, when gas is above 3 bucks a gallon, I stay employed.  Most of our local economy is related to oil and gas.  Yes, I'm in West Texas.  Right now, these fuel prices are driving exploration in parts once claimed to be too expensive to explore.  We are getting oil at 1700ft where once 10,000 plus feet had been most profitable for 1 buck a gallon gas.  Multi-million dollar directional drilling operations are affordable but, with today's gas prices driving these technologies, investors are wanting to see bigger and quicker returns.  I believe these investors are demanding these returns while politicians can only beg for some kind of political relief.  What can a president really do to lower fuel prices?  I can't think of anything but driving them higher. 

That Canadian pipeline would have been good for us yet bad for others. 

Just my 2 cents.

[ChrisOlson]

Well, presidents have no control over gas prices.  And if they do, then they got too much power and it's time to do something about it (the absolute power, not the gas prices).  I mean, the current dude set up a huge scam with the insurance industry, for pete's sake.

The current situation is so bad that nobody even has anything to select from from leadership anymore - I don't care if you belong the Democratic Party, the Republican Party, or the Beer Party.

If government is going to make it mandatory for every person to buy something they can't afford, why don't they make it mandatory for everybody to buy government subsidized powerboats instead of insurance?

At least then, everybody would be happy.  I mean, do you see anybody in that video that appears to be unhappy?  Nope.  If that was a video about government mandated insurance do you think anybody in it would be smiling except for the insurance company execs?  Of course not.  Because the insurance company execs know they're the ones that are getting the powerboats while the rest of us get the raw end of the stick.
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Chris

[fabricator]

It's all bull$hit man, you hear the republican candidates saying since Bamas been in office the price of gas has gone up. Well slap my ass and call me Sally! Prices going up! No $hit! They complain about how the gummint aint opening up enough areas for drilling, well OK MR candidate man you promise the American people if we open up every where you want opened for drilling the price of gas will go down.
It'll never Fing happen, prices will either stay the same or go up, you will NEVER see $2.50 a gallon gas again, you might see $250 a gallon but not $2.50.
Right now because of the mild winter we are actually a net EXPORTER of diesel! They increase the price to $4.10 a gallon and at the same time they are exporting diesel? WTF?
Big oil has no allegience to any flag or any country it's all about the bottom line, they could not possibly care less if they derailed the economic recovery as long as their bottom line is not hurt, and it won't be hurt, because if we can't afford it they'll sell it to China or Indonesia or who ever has the money.

[ChrisOlson]

It's all bull$hit man, you hear the republican candidates saying since Bamas been in office the price of gas has gone up. Well slap my ass and call me Sally! Prices going up! No $hit!

Don't get all worked up, OK?  LOL!
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Chris

[fabricator]

LMAO, you aint seen nothin yet

[ghurd]

We get a small fraction of our oil from Arabs

It is a world market.
It doesn't matter where it came from, or where it goes.

since Bamas been in office

It would be more accurate to look at the time from when it REMOTELY looked like he may even be a POSSIBILITY of being president.
Then look at when he took office.
And recall what the VP said... Lord help us?  Or something like that?
http://stockcharts.com/freecharts/historical/djia2000.html

[fabricator]

And the lord or somebody did help us, we got rid of curious George and his cabal.

[ghurd]

Chart above.

[ChrisOlson]

If everybody has their government subsidized powerboats out burning 125 gallons an hour at full throttle, we're going to need more gas.  A lot more.  This will keep that domestic oil production at home instead of shipping it overseas because we're not burning enough gas.  Plus it will help trade.  China always needs food.  So we can trade a couple ship loads of corn or oats or something for 1,000 tanker loads of gas from Petro China for our powerboats.  This will insure that the US remains in the #1 spot in the world for per capita consumption of petroleum.

The government already gave money away to banks so their execs could enjoy $20,000 weekends at spas in California.  And they give away $10 million airplanes, and really big guns and bombs and stuff to foreign countries.  It's time the average citizen got something for their tax dollars for a change, instead of the bill.

Powerboats are the answer¹.  I already got mine picked out.  I just need the government subsidy to buy it   

¹This all seems as logical to me as anything I've heard from the current crop of presidential candidates, including the incumbent.   
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Chris

[fabricator]

Chart above.

Note where the chart was when curious George left office.

[ghurd]

Chart above.

Note where the chart was when curious George left office.

Yea.  I saw that.
It was exactly when the new guy took over?
Or when the world knew the new guy was going to take over?

If a car catches on fire, the value goes down from what it was an hour before.

banana republic type stuff.