Power Jack grid tie inverters

solarvic

Re: Power Jack grid tie inverters

Probably true but the powerjack inverters are illegal to use. If you want to grid tie why not use approved equipment. This powerjack and other similar junk keeps getting new victims that want to justify using them and will be sorry if thier power co finds one in use and shuts off the power or your house burns down. Everytime the moderators and people that know more than I do tell you not to use this non approved equipment you want to justify using it is ok. The YOU in previous sentence isn,t specifically addressed to you only but to all that want to be illegaly using unaproved equipment. As far as I know this forum doesn,t approve garilla electrical equipment but new people buying this type of equipment keep writing to the forum about it. :Dsolarvic:D

Sparkletron

Re: Power Jack grid tie inverters

People are interested in SGPV because it's a cheap simple plug-and-play subkilo solution. Most of the time it works without issue and does not result in disaster. Yes it's illegal to use in the USA and probably most modern industrial nations. I doubt it's illegal to use everywhere. Discussing it as we are doing makes people aware of the specific dangers. I certainly learned a lot and I'm grateful to the forum and moddies for patiently explaining things in more detail.

ggunn

Re: Power Jack grid tie inverters

Sparkletron wrote: »

Most of the time it works without issue and does not result in disaster.

Would you fly on a plane that doesn't crash "most of the time"?

Sparkletron

Re: Power Jack grid tie inverters

Funny you should pick that analogy because that's exactly what Chuck Yeager did for a living. Oh wait. Actually, the planes he flew in did explode most of the time...

As I stated before, science can give us the facts, but it can't tell us what an acceptable risk is.

There are areas on the planet that don't have clean running water and flush toilets, areas with spotty power service at best, and certainly not up to our electrical code standards. Would I use an SGPV in such a place. Certainly.

ggunn

Re: Power Jack grid tie inverters

Sparkletron wrote: »

Funny you should pick that analogy because that's exactly what Chuck Yeager did for a living. Oh wait. Actually, the planes he flew in did explode most of the time...

As I stated before, science can give us the facts, but it can't tell us what an acceptable risk is.

There are areas on the planet that don't have clean running water and flush toilets, areas with spotty power service at best, and certainly not up to our electrical code standards. Would I use an SGPV in such a place. Certainly.

Of course; everything is relative. If everything you have is crap, then yet another piece of crap may be acceptable. If you risk being shot every time you leave the house, risking burning down the house isn't that big a deal.

BTW, do those things shut off when the grid goes down? If so, then it won't help with the spotty power. If not, well, then there are other problems. The most commonly cited one is that you can potentially electrocute line workers trying to restore power, but one which is seldom mentioned though which seems to me a lot more likely is that if everyone around you still has their disconnects closed, then your system would be pretty much connected to a dead short.

Also BTW, the test flights that ended in disaster attracted a lot of attention, but most were successful. I still wouldn't do it, though.

Sparkletron

Re: Power Jack grid tie inverters

Some of them do; that's one of the safety features. It would help in a brownout.

ggunn

Re: Power Jack grid tie inverters

Sparkletron wrote: »

Some of them do; that's one of the safety features. It would help in a brownout.

How so? Either it will just match the voltage it sees or it will try to raise the voltage of the grid. Either way, no help; you cannot boost the voltage in your house over the line voltage while you are connected, you cannot run a PV inverter offgrid without batteries, and 250 Watts isn't going to help the grid. Help me out here; I cannot envision a scenario whereby one of these things helps spotty power service.

Sparkletron

Re: Power Jack grid tie inverters

Depends how big your "grid" is. For a village generator in the middle of Africa, 250W may be just the ticket.

BB.

Re: Power Jack grid tie inverters

And if enough people on a village generator install GT inverters--They may damage the genset as it back feeds it (or they may take the voltage too high and/or take the frequency out of range fault the GT inverters (no damage, just 5 minute timeout)....

However, most "simple" gensets do not have stable enough frequency to support a GT inverter set to specifications (+/- about 1% frequency). Inverter-generators have very accurate frequency--Don't know how they would respond to being back-fed.

-Bill

ggunn

Re: Power Jack grid tie inverters

Sparkletron wrote: »

Depends how big your "grid" is. For a village generator in the middle of Africa, 250W may be just the ticket.

Or maybe not. I remain skeptical. A power grid, large or small, is maintained through a balancing act between supply and demand. One thing that enables residential PV to work here in the US is that the grid is comparatively huge and a residential system going up or down doesn't measurably affect it. In a situation you describe where (if) 250W is a significant portion of the grid, that 250W turning off and on may be more a destabilizing factor than a help. Also, in a situation like that I would expect that most of the loading on the grid would be at night for lighting (I don't expect that there will be much air conditioning in that African village) when your system is off line.

erikkiehle

Re: Power Jack grid tie inverters

ggunn wrote: »

Would you fly on a plane that doesn't crash "most of the time"?

Sorry guys, have a compulsion to point out that as far as I know EVERY commercial aircraft model has crashed at some point. So if you fly at all, you're guaranteed to be flying in a plane that doesn't crash "most of the time". Acceptable risk and all that. You could say the same. Your favorite car doesn't crash "most of the time" but there's still that risk .

The Boeing 737 is the most successful commercial aircraft in the history of aviation. Something like 4000 have been built and flown extensively. If you want to get scared, just look at this list of fatal 737 crashes. Sure, it doesn't crash "most of the time", but.... http://airsafe.com/events/models/b737.htm

Ugh, sorry for the "Sheldon Cooper" moment!!!

ggunn

Re: Power Jack grid tie inverters

erikkiehle wrote: »

Sorry guys, have a compulsion to point out that as far as I know EVERY commercial aircraft model has crashed at some point. So if you fly at all, you're guaranteed to be flying in a plane that doesn't crash "most of the time". Acceptable risk and all that. You could say the same. Your favorite car doesn't crash "most of the time" but there's still that risk .

The Boeing 737 is the most successful commercial aircraft in the history of aviation. Something like 4000 have been built and flown extensively. If you want to get scared, just look at this list of fatal 737 crashes. Sure, it doesn't crash "most of the time", but.... http://airsafe.com/events/models/b737.htm

Ugh, sorry for the "Sheldon Cooper" moment!!!

Allow me to rephrase my statement. Would you fly in a plane that doesn't crash on 95% of its flights? Better?

Mike at Energy Commission

Re: Power Jack grid tie inverters

Looks like "plug in to the wall socket" technology like the Chinese versions are now legal in Germany. http://cleantechnica.com/2012/12/20/plug-save-new-diy-solar-systems-from-germany/ I have heard they are legal in Australia as well, I haven't been able to verify that yet. Sure would be nice of they made these legal in the U.S. then apartment dwellers and low income folks could get in to the solar fun.

BB.

Re: Power Jack grid tie inverters

Plug in Solar will never be safe in the US/North America with our current electrical code.

Basically, you have 15 amp breaker from the utility, and up to 15 amps of power supplied by the "plug in" GT Solar system.... That is 30 amps continuous power available on a a 14 AWG wire. Enough to overheat and cause a fire.

if somebody put a 1,500 watt heater on the same circuit, one could pump >40 amps into that branch circuit and not pop a breaker or fuse.

That is why a building permit and inspection (along with its own NEC code section) is required.

And I could not see where these issues have been addressed in Germany either. Eventually, some bad stuff will happen.

Add mounting requirements (winds/hurricane/roof loading), lightning protection (don't want to bring strike energy into the apartment), etc... I could understand making the paperwork cheaper/easier, but it will never be plug and play unless new home are pre-wired with roof outlets and roof hard points. Certainly doable--But not likely to happen without more laws.

And given that the utility wants/needs to know who has solar (billing, meter, fraud prevention, insurance, code checks, infrastructure design, etc.), there still will be paper work requirements on the utility side too.

-Bill

icarus

Re: Power Jack grid tie inverters

You could "solve" it by plugging in to a dedicated circuit that has only one, dedicated receptical. For that trouble, use an conventional inverter.

Tony

Mike at Energy Commission

Re: Power Jack grid tie inverters

I haven't seen the schematics for he German plug and play, I assume the overload danger that is inherent in the current Chinese versions has been mitigated in the German version. If so it would be nice to see how they did, it circuit monitor of some type, maybe? I think plug and play would be boom to solar adoption if the risks could be worked out, the guy that patents the solution will do well. The beauty of plug and play is feeding into the grid without the soft costs and brings it all into a smaller scale, providing access to PV solar generation to a very large market. Possibly the grid operator could come up with an affordable documentation and commissioning program.

Cariboocoot

Re: Power Jack grid tie inverters

It is not possible to mitigate the overload danger because the danger is in the wiring, not the unit. As Tony said, the only way to alleviate it is with a single, dedicated circuit for the inverter - the same as any GT inverter requires. So where is the plug-n-play advantage then? There is none.

If a company wanted to develop a modular system that connected via a dedicated line and allowed inverters to be added as funds were available ... oh wait; they've already done that with microinverters.

If you want to get into it one small step at a time, go with the legit wired-in system.

gww1

Re: Power Jack grid tie inverters

I have had two of the gti's pluged in for over a year. (living dangerously "stupidly") I have never had a real system yet due to being in a differrent state due to work.

I must say I think they are the neatest thing if they could be made to work. I am probly paying to use it cause I don't know what my meter does. I will say the power through a kill-o-watt meter has been dismal for what the imput to the device says it should be. The fan runs alot but the air doesn't feel hot. It seems to be about a 30 % convertion rate, instead of the 95% percent they advertize.

I can't wait to install my signature system and hope it works better then the junk I have been playing with. If I don't go to jail, I have had some fun with my expensive toy.

I do wish more could be done to make solar and wind easier to play with and simpler to use in smaller incriments with out having to plan your all time system based on loads.

No batteries, If they converted at 95%, few fantom or inverter idle loads till needed.

Also, even though enphase has many atributes you still have to keep the system together in one spot rather then finding a hole here and a hole there to place panels.

I am not advocating the use of these devices even though I did do it. If I could and if they seemed to work better I would like to be able to.
Cheers
gww

PS I will say that even if you used ul approved equipment and installed it to code, you may still have the same problim with your electric company and insurance if you don't get the proper permission and jump through the proper hoops. The people with the money have the power in this free country. I like it here better then other countries I have been so don't take my statement out of context. Always room for improvement though.

gww1

Re: Power Jack grid tie inverters

Off subject but one thing I wish someone would invent is a grid tie system that would let you feed your house up to the loads you were using without sending extra back to the power company and without having to move your loads to sub-panels.
gww

ggunn

Re: Power Jack grid tie inverters

gww1 wrote: »

Off subject but one thing I wish someone would invent is a grid tie system that would let you feed your house up to the loads you were using without sending extra back to the power company and without having to move your loads to sub-panels.
gww

Xantrex has that but it's a battery system and it's not cheap. The problem is that without batteries a PV inverter is a current source device and must deliver the total output of the PV somewhere. If your loads are less than the inverter output, the excess goes to the grid. The other thing is that without using subpanels, the inverter has no way of knowing how much of the load it sees is local and how much is the grid.

gww1

Re: Power Jack grid tie inverters

ggunn
What does the Xantrex system do that is differrent then the outback that I have?

You mention also;

If your loads are less than the inverter output, the excess goes to the grid. The other thing is that without using subpanels, the inverter has no way of knowing how much of the load it sees is local and how much is the grid.

Does the Xantrax have this problim? How does it work?
Thanks
gww

ggunn

Re: Power Jack grid tie inverters

gww1 wrote: »

ggunn
What does the Xantrex system do that is differrent then the outback that I have?

You mention also;


Does the Xantrax have this problim? How does it work?
Thanks
gww

I am no Xantrex expert, but my understanding is that if you don't turn on the "sell" mode it will not export power from its AC1 port.

inetdog

Re: Power Jack grid tie inverters

gww1 wrote: »

The other thing is that without using subpanels, the inverter has no way of knowing how much of the load it sees is local and how much is the grid.

Does the Xantrex have this problem? How does it work?
Thanks
gww

If the inverter is connected to both the grid and local load at a single connection point (like a backfed breaker) it has no way of knowing where its output is going. The Xantrex forces you to wire the incoming grid connection onto one set of terminals (AC1 or AC2) and to connect the load to a different set of terminals (AC Out). That way it can use internal circuitry similar to that in a regular power meter to determine which direction (overall) the AC power is flowing.
One of the things that ggunn is referring to is that to do this either the Xantrex must be capable of handling the entire supply current to your home through its internal transfer switch and wiring (meaning a relatively small set of house loads and a small service panel) or you must split up your loads so that only a subset which is within the Xantrex transfer switch's rating is being powered from the AC inputs.
The former is usually not a problem for an off-grid home that has a generator, but is rarely if ever met with an on-grid home with conventional wiring.

gww1

Re: Power Jack grid tie inverters

ggunn
I am even less of a Xantrax expert as I did not understand the meaning of your answer. I guess I need to look up a Xantrax manual and read it. It sort of sounds like turning the sell off the outback system. It would be neat if you could set the outback to sell but put some kind of control at the meter that let none of the power go back but only forward. Then the grid could help support the load shortfalls but you would get full use of the pv power. I saw a disscussion on the outback technoligy forum where there was software getting close to doing this but not close enough that some power didn't slip through to the grid, there for, making a grid tie agreement with the power company still needed.
Thank you for your responce
gww

gww1

Re: Power Jack grid tie inverters

Inetdog
Basically it works just like the outback.
Thanks
gww

DaveB

Re: Power Jack grid tie inverters

gww1 wrote: »

ggunn
I am even less of a Xantrax expert as I did not understand the meaning of your answer. I guess I need to look up a Xantrax manual and read it. It sort of sounds like turning the sell off the outback system. It would be neat if you could set the outback to sell but put some kind of control at the meter that let none of the power go back but only forward.

This was originally considered years ago by Outback but they determined there was not enough interest in it by installers to add this feature. I sure would have liked this feature.

tallgirl

Re: Power Jack grid tie inverters

DaveB wrote: »

This was originally considered years ago by Outback but they determined there was not enough interest in it by installers to add this feature. I sure would have liked this feature.

I messed with adding a feature to do that a few years back. The greenMonitor software would calculate the 6 hour projected production and consumption and make DROP / USE decisions based on that. It even worked fairly well -- I greatly reduced the amount of energy I was selling to the PoCo. Then I got a Mate 3 and it didn't take commands at the time, so I stopped bothering.

I'm not sure it's worth it. It cycles the batteries almost as much as an off-grid home and that's not the easiest thing in the world on batteries. Since the spread between BUY and SELL is $0.033 / kWh for me, it's REALLY not worth it. It was especially hard in the Spring and Fall when consumption was closest to production. I was cycling to 80% SOC every day just so I'd have spare capacity in the batteries for what would get produced the next day.

inetdog

Re: Power Jack grid tie inverters

tallgirl wrote: »

I'm not sure it's worth it. It cycles the batteries almost as much as an off-grid home and that's not the easiest thing in the world on batteries. Since the spread between BUY and SELL is $0.033 / kWh for me, it's REALLY not worth it. It was especially hard in the Spring and Fall when consumption was closest to production. I was cycling to 80% SOC every day just so I'd have spare capacity in the batteries for what would get produced the next day.

With some credible estimates of the combined cost of PV and battery cycling ranging from an absolute low of $.50/kWh up as high as $2.00/kWh, you really should believe that it is not worth it.

It seems best suited to people who not only cannot get Net Metering but are not allowed to push back power at all. Sort of a capped grid tie situation, with the idea of never actually cycling batteries if possible.

gww1

Re: Power Jack grid tie inverters

Tallgirl and inetdog
I still think it would be neat for someone who isn't going to be grid tied due to poco having rules against things like homemade wind turbins and such. Or for those who just don't want the hassel of jumping through all the hoops that poco puts out there. If I remember correctly tallgirl you did a little aurguing with the powers that be which is why you were inventing the software. If you are going to run as off grid but want to keep your grid backup I think it would still be neat. I don't know if the demand would justify it though.
gww

tallgirl

Re: Power Jack grid tie inverters

inetdog wrote: »

With some credible estimates of the combined cost of PV and battery cycling ranging from an absolute low of $.50/kWh up as high as $2.00/kWh, you really should believe that it is not worth it.

It seems best suited to people who not only cannot get Net Metering but are not allowed to push back power at all. Sort of a capped grid tie situation, with the idea of never actually cycling batteries if possible.

That absolute low value is entirely too high. I'd believe that for a pure off-grid environment where there's no choice but to cycle to a lower SOC or turn on a generator, but not for what I was doing.

The key cost drivers I see for this sort of application is buying "Cadillac" batteries (top of the line "solar" batteries) when "Chevy" batteries (the much maligned Sam's Club golf cart batteries, as an example) are more than sufficient.

For that matter, the key cost driver for solar power installs in a grid-tied environment is buying "solar" batteries and following the conventional wisdom about replacing batteries. Everyone that I know, without exception, who bought a bank of "cheap", "non-solar" batteries for whatever reason has found that they lasted far longer than expected and had a lower annualized cost than major brand "solar" batteries.

For off-grid installations I'd still recommend major brand batteries, but for grid-interactive, battery-backed systems I'd recommend something in a golf cart battery from Sam's Club or other golf cart supplier.