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Forum Index : Electronics : Opinions on this little grid-tie inverter
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| adric22 Regular Member  Joined: 06/08/2008 Location: United StatesPosts: 47 |
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130248094 859 I was looking at this thing. It is very convenient and easy to install. But it is limited to 200W. But you can stack them in parallel to add more wattage. So a typical wind generator would need two of these. It would cost me $375 (once you pay shipping) to get one of these. I'd like to be able to have a renewable engery budget and every month add a few more solar panels or wind generator, etc.. But that is tough to do when I would have to cough up a few thousand for an expensive grid-tie inverter. Some questions spring to mind. First of all, I'm pretty sure my home uses 200W of power at all times, even if the A/C or heater is not running. So a single unit would probably do its job without question. but what about if I had 600W of power going into the home in this manner? What about when my home isn't using that much power? Does every electric meter have the ability to spin backwards, or do you have to get a special one to do that? I suppose I could find out by buying one of these and shutting everything off in the house and watching the meter. I suppose another advantage is that if one unit burns out, you aren't out thousands of Dollars like with a larger unit. Plus you could keep working on the remaining units. |
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oztules Guru  Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Your link does not work. The space up near the end stops it from going. try this link your home uses only 200watts, them it is very modest usage indeed for a grid residence. I can only assume something may be wrong with your measurements. Yes the inverter will do the job of pushing 200-250 watts into the grid. Whether this is allowed or not is for you to find out. Yes all grid tie inverters are "stackable" as they take their sync signal from the low impedance mains supply. Different meter styles do different things. If yours is a rotating disc type, chances are it will run it backwards. At that modest power level, I assume it may slow it a bit, but to run backwards you will have to turn off all appliances, and lights, and then it will rotate very slowly backwards. It will however, bring down your bill by 200watts/per hour. for one unit if you can feed it at that rate... probably 60-70 cents per day .......oztules Village idiot...or... just another hack out of his depth |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi oztules, I looked at the units described on ebay. They have a very narrow voltage range and it is quite clear from the disclaimers in the ad that they are designed for a particular panel type. Monocrystaline types of 24-50V MAX Open cct voltage. There is mention of a wind model. I cannot see this working unless input voltage protection measures were put in place. You probably should have double redundant protection if grid connecting. This is a result of anti islanding grid connection protection in the inverter. Great for solar. Wonder of there are 250V systems? Gordon. become more energy aware |
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| oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Hi Gordon, Yes it looks like a very tight voltage band... If I were using wind I think I would be very careful about >28v and current limit the input (and a voltage clamp) They look like a forerunner of some good things to come from perhaps Taiwan or China. ........oztules Village idiot...or... just another hack out of his depth |
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| adric22 Regular Member Joined: 06/08/2008 Location: United StatesPosts: 47 |
You misunderstood. I was saying that my house is always consuming at minimum, 200 watts. Most of the time it would be a lot more. Which means a 200 watt inverter would pretty much always be utilized even if my meter cannot run backwards. However, I've done more research on this and I think it is useless. If my calculations are correct, even if it ran at its peek 200 watts all the time, I would only save 4.8 KwH per day. Since I pay 13.4 cents per KwH, then I would save about 64 cents per day or roughly $20 per month. Unfortunately, the cost of the inverter alone would take 19 months to pay for itself. If these little things would come down in price some more, maybe about half what they cost now, then I be they would be well worth the cost. |
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marcwolf Senior Member Joined: 08/06/2009 Location: AustraliaPosts: 119 |
Hi Folks I have just dropped a topic on the forum for these Here are the lastest specs for them Brand Power Jack Model No. PSWGT-300 Continuous Output Power 300W Max Output Power 600W Output Wave Form PURE SINE WAVE DC Input Voltage DC 14 Volt – 28Volt(solar panel) AC Output Voltage AC 195v-240v Frequency 50Hz-60Hz Efficiency 90% No Load current Draw 0.7A Distortion 2% Temperature Protection 55C ± 5 Net Weight 2.0 kg Made in Taiwan So 300W (600W peak) and it can output 240V. Its about $200 on Ebay (look up Grid Tie Inverter) Hopes this help someone. Dave Coding Coding Coding.. Keep those keyboards coding.. RAW CODE!!!!! |
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KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Which is why Americans use more power than anyone else in the entire world. For most of use here its about 3 or 4 things, a hobby and our contribution to the environment and being energy independant Leaving our children a world to live in. every little bit counts. My tip -better to start today as a hobby and in 5-10 years you'll have enough kit accumulated to be energy independent. Biodiesel is a good example setup cost may be a couple of grand but ongoing cost is just 0.10cpl. feed in cost few hundred bills ongoing cost.... nothing No brainer unless you're broke. Luck favours the well prepared |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi All I have purchased six of these at a reasonable price  and plan to use two on each phase as a energy dump system on the batteries, trials so far with one works ok no smoke escaped when connected to the battery and dumping set at 27 volts, 24 volt nominal system, just inside the spec of the unit rated 15 to 28 volt. More volts less amps I hope. Switch out for equalisation charge. Running desulphators on each bank has resulted in less equalisation problems, dont need to boil the guts out of batteries to get rid of sulphation. 
Waiting for grid tie three phase meter to be fitted in january for productivity testing in parellel to one kw commercial unit Will keep you updated in the new year. All the best Bob Foolin Around |
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| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Awesome Bob.... two on each phase......300++W each 1800W out of an F&P.... perhaps optimistic but I like the way its going! Karl Luck favours the well prepared |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Karl Glad you like the idea it is a dump load for all my experiments it runs off the battery bank as soon as the batteries are charged extra output is drawn from the battery to the grid that way it works off the wind mill and the solar cellsthat all dump into the battery bank it also protects the inverters from excess voltage spikes from mill and solar panels as I have measured as high as50 volts off open circuit solar panels on a cool sunny day the old mill I have also gets to 60 volts unloaded. Nor sure of the origin of the generator but puts 15 amps into batteries in moderate wind strong wind will bring up 30 amps Think it was a davey 32 v unit origionally much modified 3.6 m 3hree blade with 6 to one belt reduction to generator. Prbably 50 years old and well past use by date hence the FP experiment looking in the future for a multiple rotor to get more amps. All the best Bob Foolin Around |
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windy city Newbie  Joined: 19/02/2010 Location: AustraliaPosts: 8 |
Karl how does this work any chance of getting a simple diagram of your setup please.  I started out with nothing... I still have most of it. |
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| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Here is a schematic i drew a while back, it has evolved a little but more in the layout than the schematic as such. 
For next time, I'm going to lash out and buy an LAtronics TC48 or TC96. Unless you can get batteries real cheap (i got mine for less then $1/AH for new AGM's) and they aren't cheap enough! 160AH = $600 PL20=$280 thus $880 + everything else required for a battery system. $800 gets you a TC 48 turbine controller and dump load. My circuit is suitable for use with any Grid tied inverter and prevents it seeing too much voltage which it would do if the grid went down. Poof - all gone! the circuit for battery charging shown on the site is AOK for a little GTI and a small battery bank. ie 40AH would do it, smooth it out enough not to smoke these GTI's. They are illegal of course (the power Jack jobs) keep that in mind if you are hoping to collect any real money from your investment. Luck favours the well prepared |
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| windy city Newbie Joined: 19/02/2010 Location: AustraliaPosts: 8 |
Karlj it looks good. I am not trying to make money at this point just save some. I am putting a 2Kw solar set up in soon. Will any power i put back into my system at home be counted as though it came from the solar aray ??? I started out with nothing... I still have most of it. |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Windy It is easier to get forgiveness than permission, once your system is in place you dont want to confuse the bean counters as to where the power comes from it somehow is just there, that is the beauty of these plug in piggyback GTI units, set up with a bit of control so the smoke stays in the box. All the best Bob Foolin Around |
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| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
apparently they can identify it quite easily, it does depend on how greedy you get, if you get 2KW of solar and then running a little farm of piggy back GTI's and have a 2KW windmill then at some point your system will deliver 4KW to the grid and they will send someone around to inspect whats going on. BUT if you had 2KW solar and worked out your house base load at 600W (fridge, freezer, tv's on standby etc etc etc) then you could get away with something to cover that 600W and not get sprung. do you want to connect more panels or a wind system? Luck favours the well prepared |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
600W base load. This is over 14kWh/day, and this is the minimum. My house, base load is around 120W, and the average load is under 300W, including cooking. I am working to reduce the base load to around 50W, without just switching everything OFF. If I forget to put the pvr in standby, then this can double the base load for example. Gordon. become more energy aware |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Gordon I will be very interested to see if you can reduce your base load to that extent as I am finding it difficult to get that low without seperating systems and fitting more batteries and solar panels ans wind mills. If I use line power I cant get below 350 watts with average 1200 watts, the solar HWS will help this a lot when they get around to fitting it. By going into turn of at the wall of all appliences it saves another 20 watt not enough to worry about. All the best Bob Foolin Around |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Bob, Yes the fridge is the key. This was todays base load. 
minimum power was 60W, and when the fridge comes on 189W. approx duty cycle of the fridge is 20%ON. Gordon. become more energy aware |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
HI gordon I suspected that the fridge was half the problem as mine has a duty cycle of 33% so I have ordered a new high efficiency one as mine is old enough to vote and won't die a natural death. When I retire it I will convert it to a 24 volt unit and see if I can get better efficiency that way. I asked my friend a fridgie and he came back with a unit 24 volt 5 amps 125 watt as against the 200 watt unit in the fridge now, with the hot weather we have had this year it has been running a lot longer than usual. All the best Bob Foolin Around |
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Dingdoc Regular Member Joined: 23/09/2009 Location: AustraliaPosts: 76 |
Concerning the 'Power Jack' type GTI inverters mentioned earlier, I was thinking about the safety aspect of these as, by plugging them into a power point, they are feeding power into the house wiring after the fuses/circuit breakers. Thus it may be possible for the wiring on a power circuit to be carrying a higher current than its safe rating without tripping the breakers, with the excess being contributed by the inverter. Admittedly, it would probably take a set of exceptional circumstances to produce a dangerous situation but Murphy is cunning!! I wonder what other forum members thoughts are on this. Trev |
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