car inverter

luvit · February 2009

don't shoot me down... yet.

i tried to search this answer, i'm sure it's been asked a million times.

this is just for testing!

can i use my 500W(4A) power inverter just to test grid tie for a few minutes?

this is a 4H project and i would like to avoid purchases i don't need for a "lab".

essentially i'd turn off all breakers in the house, except for the main switch, and capture our power meter running backwards (super slow?).

thanks. (:

BB. · February 2009

Re: car inverter

NO!

Don't do this--I have no idea what type of off-grid inverter you have but--but more than likely, you will be surprised by several thousand watts being pumped into your inverter/battery until a breaker opens or you set your home on fire.

-Bill

PS: If you want to discuss more--we can--but do not do what you plan... At best you will pop a breaker and destroy your inverter.

niel · February 2009

Re: car inverter

DON"T DO THIS!!!!!!!!!!!!!!!!!!!!!!!!!

the only inverters that can be put to the grid are the ones approved for that purpose. placing a non-approved inverter to the grid will minimally result in fireworks and a loss of your inverter.

luvit · February 2009

Re: car inverter

didn't mean to alarm you. lol.

i was just curious since i couldn't find a silly question like this. thanks.

i'll be visiting here often. i have a lot of off grid experience.

BB. · February 2009

Re: car inverter

Luvit,

Grid Tied inverters and Off-Grid inverters--while they seem like almost the same thing, the internal control circuits are entirely different...

An off-grid inverter is a regulated output (voltage and frequency), and only outputs as much current as required by the load. If you know electricity theory--an off-grid inverter is the AC equivalent of a voltage source.

A Grid Tied inverter instead is a slave to the grid (voltage and frequency)--it outputs as much current as it's DC input will allow (typically solar panels, although there are some that can use the voltage set point of a battery bank to control the AC output). The Grid Tied inverter is the AC equivalent of a current source.

The reason that we are so careful here--is that, obviously, there is enough energy involved to cause serious damage, injury, or death...

Backup AC generator systems are setup so that they "isolate" the home (using a transfer switch) to drive the interior wiring. There have been people that have been killed or killed others that have attempted to connect their AC backup generator to their homes.

There is also other issues with off-grid MSW (modified sine/square wave) inverters--Most of them will short out and or cause a shock if one of the output leads is connected to earth ground--and the battery bank/case is also connected to earth ground. And North American 120/240 split phase wiring connects the common/neutral to earth ground.

There are several projects that you could do--one of them involves purchasing a "kill-a-watt" meter and measuring the amount of energy that your home appliances use--and what can be done to conserve...

Even though this board, and the Northern Arizona Wind&Sun company is defined by its primary goal of producing electricity from the sun--we pretty much tell everyone here who asks--do all of the conservation you can first (insulation, double pane windows, energystar appliances, turning off unused loads, etc.)... It is almost always a better investment/cheaper to conserve a kWhr of power than to generate it.

-Bill

homerramirez · February 2009

Re: car inverter

No offence, this is the 2nd. post today were somebody is thinking on doing some thing that is not safe, Guys, Guys, B.B. has been good to all of us with a lots of technical advice.....PLEASE do not work with electricity if you don't have some knowledge or experience with it...again, please do not cause him a hearth attack...:p

luvit · February 2009

Re: car inverter

homerramirez wrote: »

No offence, this is the 2nd. post today were somebody is thinking on doing some thing that is not safe, Guys, Guys, B.B. has been good to all of us with a lots of technical advice.....PLEASE do not work with electricity if you don't have some knowledge or experience with it...again, please do not cause him a hearth attack...:p

i had no plans to do this, homerramirez.
i simply asked in optimism... or if someone knew of a add-on module to complete this "lab" environment. lol.

i'm not in this to save a buck. it's simply a lab experiment for my child in 4-H.

BB. · February 2009

Re: car inverter

The only legal "small" grid tied inverter out there right now is:

Enphase Micro-inverter Grid-Tie Systems
Enphase solar micro-inverters & system components

They are "cheap" as far as inverters go (~$200 for 200 watt GT Inverter).

But, you would need a 200 watt solar panel to drive it--another ~$800 plus shipping and tax.

The other issue is that it is technically illegal to temporarily connect one of these inverters to your home--although, not really risky. The missing part is permanently mounting the panel and properly wiring per code. Adding a breaker in the panel, conduit, proper grounding, mounting so the wind does not take the panel away, UV rated wiring, etc... Just not easy to do it the first time without someone with experience helping you (not me. :roll: ).

I forgot to add the link earlier--but the "Kill-A-Watt" meter is about the best tool out there to not only teach about 120 VAC power usage--it is also great for teaching conservation. Less than $30.

Kill-A-Watt AC Power Monitor Meter
P4400 Cumulative Killowatt-Hour Monitor

There is nothing out there that even comes close to these meters for Price/Performance for measuring 120 VAC 15 amp power.

And don't worry--I am not going to have a heart attack. But I will feel really sad if somebody gets hurt or worse.

-Bill

luvit · February 2009

Re: car inverter

BB. wrote: »

...you would need a 200 watt solar panel to drive it

lol.
my off grid panels are 310 watts. i was hoping to use one of those....oh well.
i'll look at an inverter that supports higher watts.

i've been supporting my small off grid application for 4 years. i think for this lab we'll be able to avoid some "code" requirements, just to capture the proof of concept.

since it costs so much, i'll likely have it installed properly in September when the 2nd lab is finished.

thanks for the great respnses, BB.

mike95490 · February 2009

Re: car inverter

Except for the "Enphase solar micro-inverters", and the $1,000+ Grid tie inverters, there is NOTHING else that is capable of being connected to the grid. I mean, you coudl hook the wires up, but you would get instant smoke.
Connecting your 300W panel to the Enphase, *might* work, as power harvest varys widely thruout the day. And it won't happen quick, the inverter needs to calib and sync with good clean grid power for 5 minutes before it will power on. Any power glitch will shutdown the inverter for 5 minutes.

Check the compatibality chart, if your panel has the right voltage/amps
http://www.enphaseenergy.com/downloads/Enphase_Module_Compatibility_List_082111.pdf

Cariboocoot · February 2009

Re: car inverter

When I first read this I nearly had a heart attack too.

But then I got to thinking ...

Can you take this lab experiment TOTALLY off-grid?

You don't actually need the real AC power grid to demonstrate the principal: Just a load, two power sources (one of them the solar powered inverter) and the necessary meters to demonstrate the voltages and currents at the various points.

You have a load of 'X' watts, and meters showing the voltage at the load point and the current flowing to it.

You have an AC voltage source - generator, isolated AC line, or one inverter - and show its output in volts and the current flowing from it.

In between you switch in the inverter source with its own volt/amp meters. The primary AC source should show its current drop to zero but maintain voltage. Thus the load is being fed off the solar panel. This doesn't show feeding the grid, but the unused potential of the inverter is there. Perhaps there is a stand-alone watt meter available that could duplicate a household meter?

I'll let the experts work out the details, but for a science project hooking up a demonstration of the principal does not necessarily require actual grid-tie.

BB. · February 2009

Re: car inverter

If I was designing a GT inverter (and if unicorns had wings)--If your 310 watt panel is a 72 cell design, the Enphase should limit/regulate its output to 200 watts maximum and run there all day long just fine.

It would just be a "waste" of the potential of a 310 watt panel to run it at 200 watts.

For a $200 lab setup--protect the 240 Volt AC mains with a 1-3 amp fuse/breaker--not the most dangerous setup in the world... (arc welders and electric hair driers are, and have you ever seen an electric stove element "pop" and go right through an aluminum frying pan?

).

If you had an "inverter style" generator and a 200+ watt load (might need a 240:120 VAC autowound transformer if you don't have a 240 VAC generator)--you could use that as your "off-grid" setup--but I would be OK with the Enphase on-grid. Your risk is the Enphase inverter failing (which it should not--if well designed).

As always--operating any electrical equipment "off-spec." and ignoring NEC/Code Requirements brings with it some risk.

-Bill

You could also connect the Enphase with a 300+ watt off-grid inverter--and the Enphase can actually pump current back through (back drive) the off-grid inverter and charge your battery bank. The two inverters will share power on the common AC point (excess power will charge the battery bank, excess load will discharge the battery bank).

This experiment is actually a relatively unknown aspect of on-grid / off-grid inverter interaction. A few companies have documented systems designed this way (SkyStream GT wind turbine is one).

I have one question--I know that this has been documented using specific models of True Sine Wave inverters (TSW). I don't know if the same is possible with a MSW (Modified Square/Sine Wave) inverter...

Solar Guppy?

The one big issue with connecting this way--is the battery bank is subjected to unregulated charging. There are several ways to address this (dump controller or use a voltage comparator to cut the AC power from the Enphase)--but for a demonstration project--this would be very interesting (for those that understand what is going on).

I would be tempted to use this Inverter--About the right size and it is TSW (you would still need an autowound or Isolation transformer as this is 115:240 VAC connection between the two):

Morningstar SureSine, 300 Watt Sine Wave Inverter 115VAC

-Bill

Brock · February 2009

Re: car inverter

To further elaborate on grid tie or standard off the shelf inverters.

Let’s think of moving vehicles. Let’s say the grid is a freight train running 240 mph down the tracks. For an inverter to be able to sync up to it, it has to know what track the train is on, be able to get on those tracks and move down them at the same speed and same direction, then toss a line over to the train and speed up a bit to help pull the train down the track reducing the load on the trains engine (power plant). This is basically what grid tie inverters to. If they see the train is stopped, they stop as well, or if the train is behaving odd, they just won’t get on the tracks.

A standalone inverter is like a car that just runs in any direction and at whatever speed it is made to run and down any path it can find. It doesn’t know to look for tracks much less match any speed of anything on the tracks.

Basically connecting a non grid tie inverter to the grid is like driving blindly (not even on the tracks but in a rail yard) at high speeds to see if you catch the train or it catches you running in the opposite direction.

This isn't just about what is legal or not legal, there are some not-legal or non-UL certified inverters that clam they can do grid tie. Maybe they can, but you’re playing with a speeding train that could seriously injure or kill you or a lineman working on the lines.

Solar Guppy · February 2009

Re: car inverter

BB. wrote: »

I have one question--I know that this has been documented using specific models of True Sine Wave inverters (TSW). I don't know if the same is possible with a MSW (Modified Square/Sine Wave) inverter...

Solar Guppy?
-Bill

Not a chance a GT could sync to a mod-sine, GT's are designed specifically for the sinusoidal wave form

icarus · February 2009

Re: car inverter

This all sort of begs the question as to what is the the OP is trying to achieve? Demonstrate that solar can power things? In the OP he suggests that plugging in the inverter and shutting off all the breakers just to show the meter going backwards..

Isn't similarly effective demo available, using his solar panel, with or without a battery, using his present inverter, a simple $20 kill-a-watt meter and a light bulb?

The net effect is the same,,, that is sun in one side, work out the other with a meter telling you how much energy (net) is used.

It seems perhaps we are all making this way too hard. I agree that running a Eu 1000 into a utility meter, with the inverter plugged in a mock breaker panel would demonstrate the concept better, but it sounds like it is way to hard to sync, plus it will get expensive for the OP.

Tony

luvit · February 2009

Re: car inverter

icarus wrote: »

This all sort of begs the question as to what is the the OP is trying to achieve? ... In the OP he suggests that plugging in the inverter and shutting off all the breakers just to show the meter going backwards..

Isn't similarly effective demo available, using his solar panel, with or without a battery, using his present inverter, a simple $20 kill-a-watt meter and a light bulb?

The net effect is the same,,, that is sun in one side, work out the other with a meter telling you how much energy (net) is used.

It seems perhaps we are all making this way too hard. I agree that running a Eu 1000 into a utility meter, with the inverter plugged in a mock breaker panel would demonstrate the concept better, but it sounds like it is way to hard to sync, plus it will get expensive for the OP.

yeah... everyone knows solar panels power things and charge batteries. anyone can demonstrate off grid with a solar calculator. -- we just wanted a small scale lab (affordable) with real-world effects.

it's funny how so many people don't know what grid-tie is unless they watch "living with ed". so we just wanted a quick and dirty lab.

after doing the math, we may not do this lab. unless i missed something... BB was pretty deep in his last post.

niel · February 2009

Re: car inverter

gt = grid tie (or is that grid-tie? i'm not a spelling major).
pv = photovoltaic panel.
i would also say that a pv, controller, battery, inverter, power meter like the killawatt, and some lights is far more than a solar calculation. the only difference is that this would be a self-contained system and you propose to feed the grid as the load with your idea. your idea is more expensive and complicated than a small self-contained offgrid example for show, but neither is cheap.
ps not that it matters, but why the need for stealth out of curiousity? no, the general membership can't see you, but i can.;)

icarus · February 2009

Re: car inverter

Luvit,

I think your idea is worthy. I think you could create a model that serves as a great demonstration bed,, without doing the whole grid tie (GT) thing. In simple terms, as a teaching tool, you could wire one load, plugged into a Kill-a-watt. You could then wire a similar load into a PV panel and inverter (with a battery used only as a buffer) use another kill-a-watt. At the end of a session, the numbers could be interpreted in a well that spells out how much the power would have cost from either source. Your 300 watt panel and a msw inverter, would power a considerable number of lights, or to make it more interesting, a light, a lap top, a stereo,,, in other words things that people use in real life.

I do understand how it would have more of a wow factor if you could watch a utility meter turn backwards. You could do this by getting two surplus meters from you local utility. (they often will give old ones away,, especially to good causes!) Wire those in to two meter bases. The grid one wired to measure the load going through,, the other wired essentially backwards,, so that you could see the net effect the same way.

You could then explain (with visual aids!) how a grid tie inverter works by having a simple breaker box wired on either or both sides, and show how a grid tie inverter would be wired, and explain the dangers of improper installation,,, fires,, electrocution etc.

Sound like a great 4H project. You could probably get you local electrical supply house to donate some stuff,,, or find a electrical contractor who does re-wire work, and have him save you a couple of old meter bases, panels etc. Wouldn't cost much.

Just my thoughts,

Tony

luvit · February 2009

Re: car inverter

niel wrote: »

g...but neither is cheap.
ps not that it matters, but why the need for stealth out of curiousity? no, the general membership can't see you, but i can.;)

lol. yeah... i saw the red dot as soon as i turned it on.

stealth is habit... if i'm a permanent fixture at a forum i give lots of good solutions, which can lead to PMs. (I.M. effect).

sometimes people write more thorough responses because they think i'm offline instead of writing short responses which tend to be a ping pong conversation.

in the couple forums i mod, i do it to avoid excessive PMs.

Tony: surplus meter is a great idea. thank you!

BB. · February 2009

Re: car inverter

If you also can use a nice integrated meter for DC (batteries, Radio Control, etc.)--take a look here. The combo-meters are pretty nice and reasonably priced.

Put a Kill-A-Watt on the AC side, and a DC multi-meter Watt's Up or Doc Wattson on the battery side (you could also put one on the solar panel side too).

One person here preferred the Watt's Up--found it more accurate. There are good reviews around the web too.

-Bill

niel · February 2009

Re: car inverter

ok on that, but i don't think this forum will quite look like the others you refer to as we like to do most of what we want to say here on the forum itself.
getting back to the subject, a grid-tie setup will be more expensive to do for demonstration purposes. you will see that being the that 200w gt micro-inverter is too small for you that you need to set your sights on something like 700w from sunnyboy at a much much larger price. >$1500 here for that particular one. for demonstration purposes i'd stay at or below the 200w for the micro-inverter to keep costs down or maybe run 2 of them if you have to have more than 200w. what people see is a meter running backwards by that amount of power, but if you use more power than generated, it will still push foreward. a utility power meter you can use in an off-grid self contained setup just to show that meter moving.
i'm not going to tell you how to do your demo as that's up to you. just keep in mind that as a demo it can and will get far more expensive with a larger than 200w full grid-tie system. i do hope it will be put into daily use and not just as a demo as that would seem such a waste.
were the other boards you refer to solar and what do you think of this board so far? we do overlook saying welcome to newcomers sometimes as it is hard for us to welcome every newcomer every time and we generally get lost into the subject matter rather than just being social. welcome anyway though.:D

luvit · February 2009

Re: car inverter

niel wrote: »

grid-tie setup will be more expensive to do for demonstration purposes. ...but if you use more power than generated, it will still push foreward.

lol, i know i know...
i didn't write a book in the OP of all my experience and research.
it's so expensive, that's why i was curious about the only missing piece of value -- the inverter.

niel wrote: »

were the other boards you refer to solar and what do you think of this board so far? we do overlook saying welcome to newcomers sometimes as it is hard for us to welcome every newcomer every time and we generally get lost into the subject matter rather than just being social. welcome anyway though.:D

this is the first solar wind forum i've visited. you guys provided great answers instead of just writing "that's stupid!", "you'll shoot your eye out", "get educated", etc.

googled: solar wind forums -- i feel lucky.

the other boards i frequent regularly is a netbook forum (mod), voip forum (product specific), and a private one for home schoolers. i have launched 1 private forum and am i am considering to launch a new public forum. they each perform diferent and attract very different personalities.

niel · February 2009

Re: car inverter

i do have to say that here we do encourage reading to learn for one's own benefit and to avoid some redundancy here in addition to asking questions. we advise and kick things around, but ultimately what you do is your choice and responsibility.

n3qik · February 2009

Re: car inverter

luvit,

OT- which netbook forum ?? Currently have two EeePC's.

luvit · February 2009

Re: car inverter

niel wrote: »

i do have to say that here we do encourage reading to learn for one's own benefit and to avoid some redundancy here in addition to asking questions. we advise and kick things around, but ultimately what you do is your choice and responsibility.

uh... i know that.
to keep this thread in focus let me reiterate:
i was not able to google or find information on a common or easily attainable half-hazzard non-UL approved grid-tie inverter which provides DC-in and AC-out to run a real-world meter backwards after turning off all my other breakers in the breakerbox...

therefore i wrote this thread questioning if a square sine 500W common vehicle power inverter (DC-in and AC-out) would simulate the same thing as a lab... not a free ride to running my house and cashing-in on net-metering.

i used the search engine in this forum and apologize if a car inverter question has been asked in this forum before and i overlooked it.
all other references and solutions have been non-solicited. my only question was simply the power inverter vs a power inverter... (then i asked what GT was, lol)

n3qik wrote: »

luvit,

OT- which netbook forum ?? Currently have two EeePC's.

n3qik, this is the awesome netbook forum, lol

luvit · February 2009

Re: car inverter

move this thread to: Grid Connected Solar Electric & Wind

i think the whole weirdness of this thread was that i posted in the Solar Beginners Corner... that would explain some elementary feedback.

icarus · February 2009

Re: car inverter

I am almost loathe to post this info,, as we have had a running thread about these and similar inverters and the fact that they are not legal, and they are not UL listed etc.

I don't suggest not recommend that anyone do this but,,,, clearly people buy these units and plug them in and,,,http://shop.ebay.com/?_from=R40&_trksid=m38.l1313&_nkw=grid+tie+inverter&_sacat=See-All-Categories

If you only want to use it as a demonstration lab,,, then maybe it would be OK for that. perhaps you could talk to the utility to get permission for short demonstrations.

Tony

luvit · February 2009

Re: car inverter

icarus wrote: »

http://shop.ebay.com/?_from=R40&_trksid=m38.l1313&_nkw=grid+tie+inverter&_sacat=See-All-Categories

those are the things i found that resembled my own car power inverter... it triggered me to post this thread. q:

i would plug it in without permission from the electric company... i don't think they would miss a few minutes of power, lol.

icarus · February 2009

Re: car inverter

It is not the few minutes of power lost that I would worry about, but rather, in the unlikely event that something goes wrong and for some reason you inadvertently energize a utility line backwards at a time when it could injure someone or other wise do damage.

As I understand these non-ul listed "grid tie" inverters, they are built with anti-islanding so that if they don't "see" grid power they will shut down. The mere fact that they are not UL listed gives me pause,,, and therefor can't recommend them.

On the other hand,,, it would seem to be a way better solution than an auto parts store msw used the same way.

Tony

BB. · February 2009

Re: car inverter

Luvit,

I am OK leaving this in the "Beginners Corner"... Asking about how to connect inverters as backup to AC power or why can't my Grid Tied system run when the utility power is down--a very common question.

Yep, the utility would probably never know you connected the small inverter... However, depending on your meter, the meter may spin backwards, not spin backwards, or even spin forward if you are back feeding power. All depends on how your utility has configured the meter.

-Bill

niel · February 2009

Re: car inverter

luvit,
i am going to ask the $64,000 question. what is the make and model number of the inverter you wish to try connecting to the grid? if it is one of those old microsine inverters, they technically can tie to the grid, although not legally, providing the model you have matches the voltage and frequency of the grid as there were other models that won't match our grid. if it matches our grid then for demonstration purposes i would see nothing wrong with using one of them and they don't accept 310w in pv for the record. if you have a gt inverter like the microsine then leaving one of those connected to the grid unattended or for long periods of time, i would not do. of course use fuses/circuit breakers any time the grid is involved and possibly an on/off switch.
btw, i sense you walking on eggshells.

no need and if there's any lines crossed we would let you know. it takes allot to get into trouble here when one stays on the subject matter and even when not on the subject it still can take allot. only certain things get one banned and connecting an old microsine would not be one of them. we aren't the nec police even though we do not want anything unsafe for anybody.:D

car inverter

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