Is is possible for a GT system without batteries to be made to work in a power outage

System
System Posts: 2,511 admin
in Grid Tie and Grid Interactive Systems #1
I had a solar installer out to look at my place just over a year ago and he told my neighbor it was possible to make a grid tie system run during a power outage without having batteries. Now I am looking at installing a GT system myself and I am wondering what component he was talking about adding to make this possible. Does anyone out there know what it might be?
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    Re: Is is possible for a GT system without batteries to be made to work in a power ou

    Running what would be an off-grid system (when the power is off) without batteries? Except for some special off grid water pumping systems that work on solar and solar alone, it's news to me.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Is is possible for a GT system without batteries to be made to work in a power ou

    Welcome to the forum.

    The answer is: no.

    We go 'round this issue quite a lot here, it seems. GT inverters need an AC signal to synch to and someplace to send all the power they produce. When the grid is down, so are they so that they're not sending power over what should be dead wires and trying to energize the whole neighbourhood or the poor sod who came to fix the wires.

    That said, some have tried to provide a synch signal with generators (bad results - no place for the power to go to) and small off-grid inverters (which need a battery and then that battery tries to take all the power from the GTI's - bad results).

    Hybrid GTI's like the Xantrex XW or Outback GT series have batteries that supply power in the event of an outage. The Sunny Island from SMA is a battery-based inverter designed to take input from GTI's and works particularly well with their Sunny Boy inverters.

    But as a rule, straight GTI inverters can not supply power without some battery somewhere in the system. Their output varies according to the amount of power available from the panels and it has to have some place to send that power. If there's no AC signal to synch to, they shut down. If there is one, the power that doesn't go to loads goes somewhere; either to over-charging the battery or to back-feeding and burning up the generator. Only the systems designed for GT with back-up actually work for it.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #4
    Re: Is is possible for a GT system without batteries to be made to work in a power ou
    ritawood wrote: »
    I had a solar installer out to look at my place just over a year ago and he told my neighbor it was possible to make a grid tie system run during a power outage without having batteries. Now I am looking at installing a GT system myself and I am wondering what component he was talking about adding to make this possible. Does anyone out there know what it might be?
    This is the kind of "sales" that gives PV a black eye. 'Coot told it like it is, and whoever told your neighbor that was at best glossing over the difficulties and expense and at worst out-and-out lying to try to sell a system, unless he really didn't know any better in which case he'd better learn the technology he is trying to sell or else find another line of work.

    BTW, another reason is that the demand for power in a home does not match the power production curve of a PV system. Look at it this way: if you had to redirect every penny you received immediately without storing it anywhere and lose it if you had nowhere to send it, your finances would be unmanageable. When a PV system is operating off grid, the battery bank provides the same service with electrical power as your bank does with your money.
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #5
    Re: Is is possible for a GT system without batteries to be made to work in a power ou

    Magnum has an imnverter that will AC couple but you still need batterys. If you call them they will send you a drawing that explains how to do it.I have one they sent me but it is confidential to me and I can,t forward copys. A picture is worth more than 2000 words in this case. I was thinking of doing it but decided against it due to I already have an offgrid inverter and it can,t do this. I think that magnum inverter is the cheapest one you can get but it isn,t approved to send power to the grid. In my case I had a 2000 watt Gti inverter that magnum engineer said would work well with thier inverter. Also I think the new xantrex inverters might do this but I am not too happy about how they left me in the cold with my xantrex SW-4024 inverter. They got thier aproval to be gridtied revoked so come out with a GTI interface that made it so you could gridtie it again but didn,t make them very long. When I got enough money saved to buy the gridtie interface it was no longer available. So didn,t check them out. Xantrex inverters are probably good inverters as far as I know, but I am done with them. I probably will have to buy one of thier high voltage charge controlers just because they are the only company that has a high voltage model. Otherwise if midnight made a similar model I would be buying one from them. :Dsolarvic:D GGunn and cariboot is telling you the truth. One of the reasons it would work for me is the offgrid magnum inverter would be a 4000 watt model and my gti inverter is a 2000 watt model so shouldn,t overpower the offgrid inverter as long as you are using the electric. Now if you had a Gti inverter that has a higher watt output than the battery based inverter you would have the problems that ggunn explained. The engineer from magnum explained this to me. Some people use just one large GT inverter in thier system. Some use 2 or more smaller ones. In my case I had to use 2 smaller ones because I didn,t buy all my solar panels at the same time and the 2 different models of solar panels voltages werent compatable with each other. Now that I have 2 separate gti inverters I kind of like the situation. If one inverter breaks down I would still have some power from the remaing one while broken was bieing repaired. solarvic
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  • System2
    System2 Posts: 6,290 admin
    #6
    Re: Is is possible for a GT system without batteries to be made to work in a power ou

    Thanks. I was afraid of that based on my research. It sounded way too good to be true. I really want to have power when the grid goes down...which it does all the time out here, but I also like the idea of selling my extra power and RECs to the power company to help offset the cost...but they won't allow me to sell the RECs if I have a battery or generator backup...and the RECs pay way more than just selling the excess. I'm beginning to believe there is a conspiracy to keep us little people dependent on the power company.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #7
    Re: Is is possible for a GT system without batteries to be made to work in a power ou
    ritawood wrote: »
    Thanks. I was afraid of that based on my research. It sounded way too good to be true. I really want to have power when the grid goes down...which it does all the time out here, but I also like the idea of selling my extra power and RECs to the power company to help offset the cost...but they won't allow me to sell the RECs if I have a battery or generator backup...and the RECs pay way more than just selling the excess. I'm beginning to believe there is a conspiracy to keep us little people dependent on the power company.
    I wouldn't call it a conspiracy, exactly, but utility companies are businesses, and like all businesses, they do what they can to protect their revenue streams. At any rate, cutting the cord to the power company and being your own utility is economically unfeasible for most of us.
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #8
    Re: Is is possible for a GT system without batteries to be made to work in a power ou

    Doesn,t seem fair. Maybe someone is discouraging you or gave you some misinformation. The guys that use xantrex or schnieder should be able to tell you more. I think they are certified to sell power to the grid but you would still need batterys. Disregard my rant against xantrex in your decision. You can,t sell power to the grid with the magnum inverter because it isn,t certified. Also you can,t connect a regular home generator to sell directly to the grid. Did you talk to different installers in your area besides the one that tryed to tell you that fairy tale? If you havn,t I would recomend that you do. Also I would think if you had a pure GT Solar system you could be grid connected and have your own generator to use for power outages as long as you used a generator interlock system that can,t feed the power co under any circumstances. Using the generator for intermitant use is the most cost effective setup and you won,t need an offgrid inverter and batterys. Don,t get discouraged like I did. I bought some stuff and waited about 10 years before I overcame it. Now i am going on 2 years GTI and it wasn,t so bad or hard to get system up and running. So now I decided to put my obsolete offgrid equipment into use for power outages especially since I have freegas from my gaswell to power my grnerator, otherwise I f I didn,t already have the offgrid equipment I have I would just be gridtied and have a generator for power outages. :Dsolarvic:D
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: Is is possible for a GT system without batteries to be made to work in a power ou

    They do this because they don't want you selling them generator or battery power. In theory, with the right TOU plan in place, you could charge batteries at a low price and then sell the power back to the grid at a higher price when the demand is there; no solar panels involved.

    But on the other hand, if you've got a generator or off-grid stand-by system in your garage how are they going to know? When the utility is down, you disconnect from the grid and power up.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #10
    Re: Is is possible for a GT system without batteries to be made to work in a power ou
    Cariboocoot wrote: »
    They do this because they don't want you selling them generator or battery power. In theory, with the right TOU plan in place, you could charge batteries at a low price and then sell the power back to the grid at a higher price when the demand is there; no solar panels involved.

    But on the other hand, if you've got a generator or off-grid stand-by system in your garage how are they going to know? When the utility is down, you disconnect from the grid and power up.

    I always thought about that with Solarvic and his free gas well. Install A solar Grid-tie to get an interconnect agreement then just run a Nat Gas DC genny through a inverter and back feed the grid. It certainly would not need to be a 24X7 operation to get to net zero or slightly beyond.
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #11
    Re: Is is possible for a GT system without batteries to be made to work in a power ou

    Dave, I didn,t want to spend the money to buy a legal inverter for that so I am working on a plan similar to that. I already have aproval to feed 4.7 kwh with 2 gti inverters. Had the 1 gti on 16 kyocera 158 watt panels. Now I have 16 new panels, 16 180 wartt and 16 185 watt I am going to put on my gridtie. And then take the 16 kyocer 158 panels previously used for gridtie and use on the offgrid system. I will be having a thread about that. :Dsolarvic:D
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #12
    Re: Is is possible for a GT system without batteries to be made to work in a power ou
    solarvic wrote: »
    Dave, I didn,t want to spend the money to buy a legal inverter for that so I am working on a plan similar to that. I already have aproval to feed 4.7 kwh with 2 gti inverters. Had the 1 gti on 16 kyocera 158 watt panels. Now I have 16 new panels, 16 180 wartt and 16 185 watt I am going to put on my gridtie. And then take the 16 kyocer 158 panels previously used for gridtie and use on the offgrid system. I will be having a thread about that. :Dsolarvic:D

    Yeah I don't know if they can tell but remember if you jam to many watts at one time back into the grid they will probably know from the meter. I certainly would look at a DC generator on the original inverter to be run off that free resource. I wish I had hydro or in your case free Nat gas.
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #13
    Re: Is is possible for a GT system without batteries to be made to work in a power ou
    solar_dave wrote: »
    Yeah I don't know if they can tell but remember if you jam to many watts at one time back into the grid they will probably know from the meter. I certainly would look at a DC generator on the original inverter to be run off that free resource. I wish I had hydro or in your case free Nat gas.
    Thats the plan. My electric bill this month said I used 8 kwh per day even though I made more than I used. Them smart meters must be preety smart. I wasn,t making my imput limit with what I was approved for so I figured by going to higher watt output solar panels I would be closer to what I am approved for. I didn,t use much air this year and want to be able to use more next year. My 16 158 watts comes out to 2528 watts and the new array comes out to 2920 watts and I still have 2 panels left I might add if there is still room electrically. and is a better location. So now I hope to up th gti output maybe 400 watts output.Best I ever saw was around 3950 watt output. This should get me in the ball park as these are new panels and some of my 158 watt have been in the sun about 6 years. I have a Ng dc generator for offgrid. When I get my solar system where I want it my next project might be making bio diesel. Some people say they feel bored after they retire. So far I havn,t as now I now have time to do do some of the projects I wanted to do when I was working. I got the makings for a listeroid setup. :Dsolarvic:D
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