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Old 08-18-11, 02:11 PM   #31
Xringer
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Default A cautionary tale

My GTI experiments have been terminated, after my last mishap with a new inverter.

This summer, I purchased a Chinese 48vdc 1500w 120vac 60hz Pure SineWave inverter.
The PowerJack specs said it would do 3,000w peak load.
I found it would beep and shut down, when my new dehumidifier compressor came on.
Sometimes, it would come back on, and sometimes, it would stay off.

So, I decided to try beef up the sinewave output by adding the 1200 GTI output to the 1500w Sinewave inverter.
Wow, 2700 watts total.. But, not really. Since the 1200w GTI was connected to 800w of panels. (4 in parallel).

Anyways, it worked fine for hours. Then suddenly the (PowerJack?) AC voltage started increasing.
It hit about 150 vac, in a matter of seconds. Before I could kill the load,
the Sinewave inverter popped it's fuses (and/or transistors), gave off a little puff of smoke and died.
I have not taken the time to open it and survey the damage.

Anyways, my curiosity about tricking GTIs hasn't been cheap to satisfy..
I did learn it's possible, but maybe too tricky for the average hacker.

Cheers,
Rich

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Old 08-18-11, 02:49 PM   #32
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Quote:
Originally Posted by gbbengi View Post
Hello all,

First post! Yup, I'm a newbie!

So, here is the deal. I built myself a small sweet little battery back up bank. I am currently disconnected from local utilities, so I am technically "off grid".

Here is my video: Never mind, it wont let me post my you tube video. But if you want to find it, go to you tube, and in the address bar add this "watch?v=_Ryw-6R0l9o"

I was looking into purchasing one of the tie in inverters and "tricking it" into thinking I am on grid, I don't need it to do much, basically just power on bathroom lights when needed, and also outside lights for a couple hours per night so it looks like I have power to my neighbors! LOL (every bulb in my place is 10 watt energy star spiral)

I do have a smaller set of solar panels which I will be adding to next week, also will be getting a small wind turbine.

What is the easiest way to set it up so that I can minimally use the household wiring that I would normally be using everyday anyway? I thought about the "suicide cable" and turning all circuits off but one and putting a protective harness on the extra male end to keep it plugged in, but I was told this could still start a fire through reverse polarity, hence the reason I was looking to use the GTI-because it has reverse polarity protection.

Thanks for any help I can get!
Hello, I was able to watch your youtube movie.

In your video, I think you were charging your battery pack (from the grid) to use during off-peak hours.
I've never heard of that being a good solution to paying peak hour prices,
since charging up and then using a battery bank is very inefficient.
Way too many losses in that cycle.
When you include the price of the hardware (and periodic battery replacement), it's very expensive.


How much PV are you going to install? And how much power do you
plan to feed your off-grid appliances?

Unless you plan to use very few KW hours, going solar PV is going to be very expensive.
It's not something that most people would even consider, once they look at the cost.
Now, if you're rich, that's a different story. Since you would not care that
breaking even would take 20+ years..

Small wind turbines are pretty much a joke, when installed on a typical home site.
Location, location, Location is everything. If you don't have to hang on to
your hat while outdoors, forget it.
If you are interested, check out the Fearlessthinker videos.
Car PMA Wind Turbine performance II - Reality check - YouTube

As for connecting inverters to your house wiring via an outlet,
that can be dangerous.. The reason Enphase and others does not sell
a plug-in-the-outlet inverter system, is the fact that it won't pass code. (In the USA).

Lets say, you plug in a 1200w GTI into a 120vac socket (rated for 15a).
And then started plugging in loads to that circuit, until it was sucking
in 1800w from the grid, and 1200w from the GTI.
Now, you have 3,000 watts, ruining on a circuit designed for 1800w.

But, you don't see the wire heating up inside the walls,
so everything seems just fine. Until the clouds roll in..
Now, your 3,000 watt load is going to be fed by the grid.
That 25 amps is going to pop your 15A breaker..
But, if there's a problem and it sticks?
There is a good possibility you will see some smoke..

Check out this site for more info.. Solar Electric Power Discussion Forum by Northern Arizona Wind & Sun - Powered by vBulletin

Got to run,
Cheers,
Rich
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Old 08-18-11, 05:24 PM   #33
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Hey Xringer, if you are thinking about parting ways with one of those inverters let me know. I could put it in my car. It's overpowered to be sure but the cig lighter is dead on my new vehicle and I'm just going to wire an inverted straight to the battery with a cable for a car stereo amp.

Good luck!
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Old 08-18-11, 08:49 PM   #34
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I'm hanging on to both of my 12V inverters. They are not only handy for the car or SUV,
I can also use them on one of my little 12VDC PV setups.

These are fed by little 10w PV panels, but they do provide a bit of backup.
The black battery runs the bedroom LED lamp and the other is for Ham radio gear.


That 48Vdc sine-wave inverter might not be repairable.
I have not looked inside yet I'm glad it wasn't expensive!
But, when/if I get it going again, I will not be using it for experiments..
It would be good for running small transformer power supplies, TVs etc..
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Old 08-30-11, 02:03 AM   #35
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Hi everyone.
Interesting discussion.

The problem that I have with proposed setup, is that my PV system is setup to a very high voltage (350V) per channel, thus getting it to the batteries is a bit of a problem with a proposed setup.

But, I thought to myself, why cannot I just use 240v battery charger from the mains (Australia), that is only running during a day (timer switch). Since the solar is channeled to the mains through grid tie inverter, I'll be able to charge batteries using 240v charger. I know it would probably be less efficient, but way less wiring.

Once the batteries are charged (and not used), the charge controller would not pull much from the mains. If there is a power outage, all I would have to do is switch off the master switch (so that voltage does not go back to the mains and no one gets hurt), and connect the battery>240v inverter to the batteries. Turn it on - presto! Grid tie will think that there is power, so will start using solar to 240v conversion, which will charge the batteries through 240v>battery charge controller (plus whatever else needs power around the house)

What do you guys think? I already have 3.8kW grid tie solar installed, the only cost would be the batteries, charge controller, quality 240v inverter and some wires and switches.

Sergey

(the only thing is that batteries must be charged before the blackout)
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Old 08-30-11, 08:31 AM   #36
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Like I said above, connecting a GTI (+PV array) to a Sinewave inverter (to fool it),
does work, but sometimes, it can go nuts on you..

You idea of timer/charging batteries during the day, right off your home outlets isn't bad.
Just to use as a backup supply during power failures.

Products Applications



I've got a large Solar backup system (plus gasoline powered gen backup)
so that I can run pumps during a 2 or 3 day (maybe a week) gird failure.
Without power to my pumps, my basement can flood..
I know, it would be easier if I moved somewhere else..

Last edited by Xringer; 08-30-11 at 09:38 PM.. Reason: typos galor
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Old 08-30-11, 08:29 PM   #37
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Have to read up more on the PV vs Sinewave inverter battle.
Backup is great, but I don't want to have 10 batteries charging "just in case".
I was thinking of having, maybe, just 1 or 2. Just enough to fool the PV inverter into thinking its connected to mains. Might need to put a large diode in between, so that power does not flow back into the sine inverter
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Old 08-30-11, 08:36 PM   #38
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Have a look at this. Too bad its only 120v AC, would have to find out if they make a similar
theinverterstore.com/the-inverter-store-product.php?model=pwric300012w#
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Old 08-30-11, 08:54 PM   #39
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Sorry for spamming... The more I read the more I post =)
The link I posted above, is for a great inverter, but it is Modified sinewave, not true sinewave =( Otherwise a great product.

What I am thinking happened to those Chinese "pure sinewave" inverters, was due to those inverters been modified, not true sinewave. Thus the intermittent results.
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Old 08-30-11, 09:42 PM   #40
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Quote:
Originally Posted by SergeyAU View Post
Have to read up more on the PV vs Sinewave inverter battle.
Backup is great, but I don't want to have 10 batteries charging "just in case".
I was thinking of having, maybe, just 1 or 2. Just enough to fool the PV inverter into thinking its connected to mains. Might need to put a large diode in between, so that power does not flow back into the sine inverter

Since it's AC that's being tied together, adding a Diode, (which changes AC into DC) would likely cause a malfunction.

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