Another P&P Vendor - Can plug and play work in the US?

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  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    there is no upstream/downstream here as you are simply adding 2 separate power sources together meeting at the wiring. it did not consume power so it is not reasonable for you to say it is that low of a current on the wire. it would be 15a from the breaker and 3a from the solar meeting at the wiring for a total of 18a available on the wiring that is rated for 15a. unsafe and illegal.
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    niel wrote: »
    i am right in my example that you can get 15a plus 3a solar available on the wire for anything that could be plugged into that circuit. it is illegal to place 18a on a wire rated 15a

    And you read what I've said. I've never proposed to "to place 18a on a wire rated 15a". What I said was: line designed for 30AMP with 15AMP circuit breaker. So, line itself perfect for 30AMP load.
    Now, about your example with 18AMP connected load and 3AMP inverters load and CB at 15AMP, please explain, where in such line would you have current above 30AMP?
  • BB.BB. Super Moderators, Administrators Posts: 32,226 admin
    And I said, yes, you can design/build a wiring system that has 2-4x as much copper heavier rated outlets and such. Such devices will cost more and probably larger (more rated load, more heat, more heat, more surface area/better cooling required, and/or more metal for lower resistance).

    Everything is a trade off...

    Go look at an 10 AWG SOJ cord (used on fairly heavy equipment) or look at a drier cord for a full electric drier in your garage. And look at the lamp cord/light weight extension cords you have in your home (16 AWG is about the lightest gauge I have seen plugged directly into a 15 amp wall outlet).

    There are consiquences if you have a 30 amp rated outlet (so you can have 15 amp breaker + ~12 amp GT rated inverter power) and still use it as a "non-dedicated circuit" to replace standard outlets use throughout the home...

    Do you require these new "hybrid" 30 amp circuits everywhere in the home, just outside south facing walls with good sun exposure, etc.?

    Believe me, any changes you would like to make can make things difficult for others. A nearby city that I lived in for the first 30 years of my life changed their code to require 12 AWG wiring as the MINIMUM acceptable wiring for everything in the home (outlets, lighting, etc.). And it drove up prices for electrical work (more copper and more labor--Much more difficult to wire up a J-Box filled with 12 AWG cable vs 14 AWG cable). Everyone complained.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    niel wrote: »
    there is no upstream/downstream here as you are simply adding 2 separate power sources together meeting at the wiring. it did not consume power so it is not reasonable for you to say it is that low of a current on the wire. it would be 15a from the breaker and 3a from the solar meeting at the wiring for a total of 18a available on the wiring that is rated for 15a. unsafe and illegal.

    I have nothing else to say to you, except:
    1. In my example wiring is rated at 30AMPs;
    2. You need to learn a little bit of AC/electrical stuff. Or better having your solar panels ON just goto your meter: see immediate use in Watts and divide by Voltage => you will get current in AMPS going downstream through you meter (Inet -- current with inverter on). Now disconnect your solar panels, check meter and see immediate use now => you will get current in AMPS going downstream through you meter (Watts and divide by Voltage) that would be Iload -- current with inverter OFF).
    Production current of your solar panels would be Is=Inet-Iload. So, at anymoment through you meter we have current equal to Inet=Iload-Isolar.
    Notice => we used "-" sign, so the current through our meter was difference between Consumed energy and Produced energy. Now, replace word "meter" with "circuit breaker".
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    BB,
    My point was obviously not to build new 30AMP circuit and place outlets on it, just for the purpose of installing solar.
    I was trying to say, that if you have already free, not used and/or not that heavily used 20AMP and/or 30AMP circuits/lines -- you might consider reusing/upgrade them in order to connect P&P inverter.
    Like in my house, I had abandoned 2phase 30AMPS dryer line: at some moment electrical dryer was replaced by 1 phase 15amps gas dryer, so I had one 30AMP line, which is free to use and anoother (that is used by new dryer) is only 1/2 of possible load, as it was originally designed for 30AMPS... So, why not to reuse them? And P&P inverter is aperfect candidad, Right?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    The issue is this:

    You have two power sources capable of supplying up to their maximum current rating. The actual amount of current flowing on any point in the wire depends on that capacity, the amount actually drawn by the load, and the load's position in respect to the power sources.

    As such (dotted lines representing 14 AWG household wiring capable of 15 Amps continuous):

    MAIN PANEL 15 AMPS
    LOAD 20 AMPS ---- SOLAR 5 AMPS

    Works, as no segment of wire will have greater than 15 Amps on it. You must be sure that all points after the two power sources join are capable of handling the maximum continuous current of 20 Amps.

    Otherwise you get this:

    MAIN PANEL 15 AMPS
    SOLAR 5 AMPS
    LOAD 20 AMPS

    Where the second segment of the wiring has 20 Amps on it but is only capable of handling 15.

    This is the whole problem with plug-n-play inverters: you can never be sure that the wiring you plug them in to will provide the circuit outlined in the first description. What is more, people who install one such inverter and experience no problems (purely from random luck) go ahead and install more, thus increasing the possibility of improper circuit arrangement.

    All of this is solved by the use of properly installed (hard wired) GT inverters which direct their power to the bus bars of the main distribution panel, eliminating the possibility of wiring overloading.

    This is why the PNP inverters are technically legal for sale but illegal for installation. They are not safe and no reputable company builds them.

    And can't a guy even have a heart attack around here without being dragged back into service? :p
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    reread post #28 and apply it to your example if you can conceivably do that. if you have a 30a circuit, that's using #10 awg wire, and put a 15a cb to it instead of a 30a cb then this allows for 15a to be added via solar as the wire is rated 30a. will it be ok for plugnplay? no, as that is still illegal. it needs hard wired.

    i have more than enough knowledge of ac and i don't need told i'm stupid by you. you need to read what people are saying.
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    MAIN PANEL 15 AMPS
    LOAD 20 AMPS ---- SOLAR 5 AMPS

    Works, as no segment of wire will have greater than 15 Amps on it. You must be sure that all points after the two power sources join are capable of handling the maximum continuous current of 20 Amps.
    Wrong: how did you connect - LOAD 20 AMPS - is it through outlet => then outlet should be rated at 20AMP, Right? That's exactly what I said: line is designed for 30AMP, but breaker is 15AMP;
    MAIN PANEL 15 AMPS
    SOLAR 5 AMPS
    LOAD 20 AMPS

    Where the second segment of the wiring has 20 Amps on it but is only capable of handling 15.
    Not what I meant: as I said our wires/outlets and etc. ahould be designed for 30AMP current if we have 15AMP CB
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    igor1960 wrote: »
    Wrong: how did you connect - LOAD 20 AMPS - is it through outlet => then outlet should be rated at 20AMP, Right? That's exactly what I said: line is designed for 30AMP, but breaker is 15AMP;


    Not what I meant: as I said our wires/outlets and etc. ahould be designed for 30AMP current if we have 15AMP CB

    No, my example is 100% correct. You may need to adjust the numbers to suit the particular application but the mathematics behind it are totally accurate.

    If you use 10 AWG wire it can carry 30 Amps maximum, and again so long as the load does not exceed this on any point in the wiring it will work.

    Reducing the main panel breaker will reduce the maximum current available from the utility and thus limit the maximum current on any shared wiring. It is that shared wiring between power sources to the load that is the concern. Providing the current on that section (if there is any) does not exceed its rating it won't burn up. So you have the simple equation of: current from utility + current from solar source <= continuous current rating of wiring.
  • bill von novakbill von novak Solar Expert Posts: 891 ✭✭✭✭
    niel wrote: »
    if you think you know better than us or the nec then do what you want. putting 3a of solar to a 15a circuit does not amount to 12a net as it adds to the total current available as 15a (from cb) + 3a solar for 18a available and is too much for the wiring.

    That case is, at least, not overloading the line. The problem case is 25 amps of load and 10 amps of GT solar on a 15 amp line. Net power - 15 amps. No circuit breaker trip. If the GT inverter is closer to the load center on the home run wire than the load, then the wire between the load and the GT inverter is carrying 25 amps, which is a significant overload.
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    BB. wrote: »
    Nope--You are wrong... AC or DC does not matter here. The basic of 15 amps from Breaker + 3 amps from outlet A = 18 amps available at outlet B to an arbitrary load.

    Here I agree => we have 18AMP of available load, before breaker will trip.
    BB. wrote: »
    Breaker and wiring only "care" about current (specifically RMS current). PF, phasing, etc. does not matter in the above example. Problem would be exactly the same if this was a set of DC power sources and a DC load.

    In above example it might not matter only if current of 15 amps from Breaker is exactly synchronized with 3 amps of inverter. If they are not => we would have less then 18AMPS available at outlet, Right? And that was exactly my point: here AC is different from DC...
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    That case is, at least, not overloading the line. The problem case is 25 amps of load and 10 amps of GT solar on a 15 amp line. Net power - 15 amps. No circuit breaker trip. If the GT inverter is closer to the load center on the home run wire than the load, then the wire between the load and the GT inverter is carrying 25 amps, which is a significant overload.

    Significant overload of 15AMP line. Agree. But still underload of originally proposed 30AMP line, Right? Remember, original proposal was that "the wire gauge, outlets, switches should be for 2 times the current on circuit breaker" read message #20...

    Don't also forget that in your example when the sun goes down inverters will produce less/no current and your 25amps load will trip 15AMP circuit breaker. So, everything OK.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    igor1960 wrote: »
    Here I agree => we have 18AMP of available load, before breaker will trip.



    In above example it might not matter only if current of 15 amps from Breaker is exactly synchronized with 3 amps of inverter. If they are not => we would have less then 18AMPS available at outlet, Right? And that was exactly my point: here AC is different from DC...

    No, AC is not different from DC in current carrying. We are in fact not talking about single conductor but a circuit, and really power flow. That one type reverses direction at 60 Hz and the other goes "in one wire and out the other" isn't relevant.
  • bill von novakbill von novak Solar Expert Posts: 891 ✭✭✭✭
    igor1960 wrote: »
    Significant overload of 15AMP line. Agree. But still underload of originally proposed 30AMP line, Right? Remember, original proposal was that "the wire gauge, outlets, switches should be for 2 times the current on circuit breaker" read message #20...

    Agreed. However, how do you identify that a given outlet has a "2 times rating?" How do you ensure that the inverter doesn't get plugged into a "standard" outlet?
    Don't also forget that in your example when the sun goes down inverters will produce less/no current and your 25amps load will trip 15AMP circuit breaker. So, everything OK.

    Unless it's something (like an air conditioner) that only runs during the day . . . I can just see the homeowner patting himself on the back for his cleverness. "My old A/C used to trip the breaker all the time until I moved it to this outlet in the corner! I just saved myself $500."
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Agreed. However, how do you identify that a given outlet has a "2 times rating?" How do you ensure that the inverter doesn't get plugged into a "standard" outlet?



    Unless it's something (like an air conditioner) that only runs during the day . . . I can just see the homeowner patting himself on the back for his cleverness. "My old A/C used to trip the breaker all the time until I moved it to this outlet in the corner! I just saved myself $500."

    That is exactly the problem: it is too easy for the wiring to be altered to an unsafe state.
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    No, AC is not different from DC in current carrying. We are in fact not talking about single conductor but a circuit, and really power flow. That one type reverses direction at 60 Hz and the other goes "in one wire and out the other" isn't relevant.

    I'm sorry man: but you have to read about AC rms current, current phase, active/reactive power and etc...
    We have main available current coming from our utility company and it is pure sinusoidal exactly matching 60hz phase volts sinusoid. As it is completely active (at least that what we assume) then:

    Power Formula: Watts = Volts * Amps

    our inverters production matches the same main Volts sinusoid but with 180degrees rotation of the current relative to mains current... plus our inverter has some PF which is not equal to 1, therefore. => Available Current in any common circuit that has Main and Inverter is I=Imain-Iinverter*phaseShift, where phaseShift is shift in phase between MainCurrent and InverterCurrrent-180...
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    igor1960 wrote: »
    I'm sorry man: but you have to read about AC rms current, current phase, active/reactive power and etc...
    We have main available current coming from our utility company and it is pure sinusoidal exactly matching 60hz phase volts sinusoid. As it is completely active (at least that what we assume) then:

    Power Formula: Watts = Volts * Amps

    our inverters production matches the same main Volts sinusoid but with 180degrees rotation of the current relative to mains current... plus our inverter has some PF which is not equal to 1, therefore. => Available Current in any common circuit that has Main and Inverter is I=Imain-Iinverter*phaseShift, where phaseShift is shift in phase between MainCurrent and InverterCurrrent-180...

    No, none of that has any bearing on continuous current carrying rating of wiring and maximum current. None of it. And your inverter's output should be totally in sync with the mains power, otherwise you'd be pushing 120 Hz on the line. Inverters do not have PF; loads do. I think you have become confused by the information about the GTI in respect to viewing the utility as a load (back feeding) rather than an additional power source (where both sources are feeding a common load). Possibly you are confused about the differences in circuit interrupt ratings for a device in respect to AC and DC (because AC cross zero Volts as it cycles and thus is easier to shut down whereas DC will try to sustain an arc).

    If you had the education Bill, Niel, and I have you wouldn't even be asking the question.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    bill v n,
    good point on no cb for the load as he will need a 30a cb before the load. all the more reason for hard wiring it.

    as to the 15a + 3a on #14 wire, it's an overload. i used that as an example for him to follow to apply to his awg used in his circuit. i guess interpolation was asking too much for him to do. i should've said specifically. sue me? won't get much.;):p
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    Agreed. However, how do you identify that a given outlet has a "2 times rating?" How do you ensure that the inverter doesn't get plugged into a "standard" outlet?
    Unless it's something (like an air conditioner) that only runs during the day . . . I can just see the homeowner patting himself on the back for his cleverness. "My old A/C used to trip the breaker all the time until I moved it to this outlet in the corner! I just saved myself $500."

    Do you have to identify? So, you are plugging something and your circuit breaker trips (you said it yourself in your air conditioning example). So, you go to another outlet, circuit and correct the problem -- the same here...
    Another problem is: How do you ensure that the inverter doesn't get plugged into a "standard" outlet?

    Here we already discussed that P&P inverter might have different plug/outlet.
    However, it would not surprise me to see P&P inverters selling soon with/for the same plug/outlet as today, but together for example with different Circuit Breaker.
    Imagine circuit breaker that introduces some constant frequency into phase (can have just a small oscilattor inside). Now each P&P inverter will just check for existance of this frequency component in the line -- and if it exist will continue working, otherwise it will just put an indication like "Wrong Outlet"...
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    niel wrote: »
    bill v n,
    good point on no cb for the load as he will need a 30a cb before the load. all the more reason for hard wiring it.

    as to the 15a + 3a on #14 wire, it's an overload. i used that as an example for him to follow to apply to his awg used in his circuit.

    Unfortunately the OP seems to have difficulty grasping the abstract examples used. Maybe if he tooka few years out to get an electrical engineering degree?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    igor1960 wrote: »
    Here we already discussed that P&P inverter might have different plug/outlet.
    However, it would not surprise me to see P&P inverters selling soon with/for the same plug/outlet as today, but together for example with different Circuit Breaker.
    Imagine circuit breaker that introduces some constant frequency into phase (can have just a small oscilattor inside). Now each P&P inverter will just check for existance of this frequency component in the line -- and if it exist will continue working, otherwise it will just put an indication like "Wrong Outlet"...

    Frequency is the same on all the AC wiring in the household; it is simply "split phase" on a 120 VAC line. The inverter must sync to it; it does not have its own independent frequency.

    Since there is no way of knowing what the wiring is inside the walls (and I've come across some beauts in my day) plug-in inverter can never be made safe. There is no way for the combined power sources to know the total current available on the wiring and protect against over-current for the whole.
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    If you had the education Bill, Niel, and I have you wouldn't even be asking the question.

    Sorry, I din't know that you are all professors here!
    And your inverter's output should be totally in sync with the mains power, otherwise you'd be pushing 120 Hz on the line

    Voltage output, Yes! But Current opposite!
    So, you are the kind of "professors", who don't know that in order to charge the battery you have to provide current in opposite to the load direction.
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    Frequency is the same on all the AC wiring in the household; it is simply "split phase" on a 120 VAC line. The inverter must sync to it; it does not have its own independent frequency.

    Since there is no way of knowing what the wiring is inside the walls (and I've come across some beauts in my day) plug-in inverter can never be made safe. There is no way for the combined power sources to know the total current available on the wiring and protect against over-current for the whole.

    Again, don't want to be rude, but it doesn't look you are comprehending what I'm saying. Repeating and imagine:
    1. We have specially designed circuit breaker ("CB for P&P inverters" line). They are special: they are marked 30AMP, but in reality they will trip at 15AMPs (so it's standard 15AMPS breaker inside);
    2. In addition to 15AMPS breaker that "CB for P&P inverters" has a small electronics (oscilator) that would add some known and standard frequency to the line (for example 8khz) , so we would have 60hz major AC frequency plus for example 8khz oscilator frequency on voltage (phase);
    3. Now, we connect P&P inverter using standard plug to this line. Inverters electronics using FFT checks for presence of 8khz in the input voltage and if such frequency exists continue working, otherwise just displays "Wrong Circuit"...
    4. Other consumers connected to that circuit, would continue to work, as they have no knowledge about 8khz frequency to check.

    What is wrong with this proposal?

    In fact, having such breakers, will allow utility company to turn remote inverters off/on, as they can create the same or opposite frequencies on other standard and published frequency ranges...
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    Unfortunately the OP seems to have difficulty grasping the abstract examples used. Maybe if he tooka few years out to get an electrical engineering degree?

    What if I tell you, that I hold two Phds in Electrical Engineering and Electronics. Would this surprise you? You obviously argue this too...
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    Inverters do not have PF; loads do

    Right?
    Except, any DC/AC converter should have it, as main principle is inductive
    here it is: search for Power Factor
    Enphase Micro: http://enphase.com/wp-uploads/enphas...roinverter.pdf
    AURORA TRIO central: http://www.power-one.com/sites/power...aralleling.pdf
  • BB.BB. Super Moderators, Administrators Posts: 32,226 admin
    igor1960 wrote: »
    BB,
    My point was obviously not to build new 30AMP circuit and place outlets on it, just for the purpose of installing solar.
    I was trying to say, that if you have already free, not used and/or not that heavily used 20AMP and/or 30AMP circuits/lines -- you might consider reusing/upgrade them in order to connect P&P inverter.
    Like in my house, I had abandoned 2phase 30AMPS dryer line: at some moment electrical dryer was replaced by 1 phase 15amps gas dryer, so I had one 30AMP line, which is free to use and another (that is used by new dryer) is only 1/2 of possible load, as it was originally designed for 30AMPS... So, why not to reuse them? And P&P inverter is a perfect candidate, Right?
    Perfectly OK to re-purpose a circuit. I did exactly that with a drier circuit in my house--Dropped two 20 amp breakers and ran Red+Black+White+green to a bunch of new outlets in my 60 year old home (1x 15 amp outlet in a two car garage--What were they thinking?).

    But since you have a 240 VAC 30 amp branch circuit (note, in North America, we really don't have two phase power, we have 120/240 VAC split phase power)--2 phase power would normally be 90 degree phase angle and not 180 degree... This allows/supports a "rotating field" which is way more handy than just an transformer inverted voltage leg/phase) anyway, why not hardware your GT inverter+array in following code?

    There are still code issues to address. If you use Micro Inverters (like Enphase et.al.), they are very much like the "plug and play" without the line cord and (usually) operate at ~208 or 240 VAC vs the ~120 volts for North American P&P type inverters.

    Besides the "normal" code issues of how/where/inspections of mounting the solar array--There is the issue that Enphase only supports a maximum of 20 Amp @ 240 VAC circuit--So you would have to have a sub-panel with 20 amp (maximum) breakers, or change out the main panel from 30 to 20 amp breakers.

    Next, in the main panel--To ensure that bus bars do not carry more than their rated load, if (for example) you have your main service breaker pair at the top of the bus, the GT Solar breakers have to be at the bottom of the bus (the GT breaker cannot be next to the Main panel breakers--Then more than the bus rated capacity could be supplied by the multiple AC power sources--Just like the discussion Marc and I had about Breaker+A+B issues).

    After that, then you have to look at the rating of the bus bars (and main box sheet metal), and the main breaker. For example, a 125 Amp panel can be "uprated" for solar by 20%... 120%*125a=150a of total source current.

    Nominally, that would be 150 amp uprate - 125 Amp main = 25 amps available for GT solar feed. In your case, the 30 amp breakers would need to be dropped to 25 or 20 amps to comply.

    Now--You can install on a single Enphase branch circuit up to 20a*0.8nec derate = 16 amps of Enphase inverters + solar panels (at 240 VAC).

    I skipped through a bunch of the "other stuff" that needs to happen, but that is the basic of the design to use your "free" drier circuit. Note, if you have a sub-panel in the garage for the 25 to 20 amp breaker reduction--Most inspectors will not allow you to connect any other loads to this panel--It must be dedicated to GT Solar only (to avoid all of the confusion we have already discussed).

    One thing I just wanted to make sure I understand from your discussion... If you have a 30 amp rated outlet (regardless of the breaker feeding it), all equipment that plugs into that outlet needs to be rated for a 30 amp branch circuit (heavier wire in plug/pigtail, junction box in appliance needs to support 30 amps, etc.).

    The use of a different socket is to ensure that somebody does not mix appliances with lower ratings (i.e., 20 amp or 15 amp branch circuit maximum) to keep their UL LISTING. If you plug a 15 amp rated plug on a TV in to a 30 amp rated socket (chop off old plug and put new plug on)--That is a violation of NEC--And if it happened in an office, the fire inspector will red tag it (not all cities/counties do commercial fire inspections).

    And if you put a 20 amp rated outlet on a 30 amp rated service (i.e., 30 amp main breaker or a service that can have 30 amp of power sources), then that is illegal. A 20 amp outlet does not limit current (no breaker or ballast)--So, the 20 amp outlet is "not safe" on a "30 amp branch circuit".

    If you derate circuits, you still are supposed to go back to the main panel, look at panel capacity/main breaker/position of breaker/etc... And as I stated earlier, most (all?) building inspectors will not allow a mix/match sub-panel full of loads+GT sources.

    In the end, the whole idea is that hardware connection of power needs a bit more experience/training than simply plugging in a black box. It is intended to make things "more difficult" so the average consumer cannot install GT equipment (ignoring the whole issue of Utility insurance/approval/tariff requirements).

    Not trying to be difficult here--Just trying to be "black and white" on what is legal and what is not. House fires are very common--And we have seen many cases where even a licensed electrician (and building inspectors) have "blown it". And sometimes fire "happen" (corroded connections, issues with high voltage/lower current solar connections that "arc fault", etc.).

    At this point, I still do not see any way of making a "plug&play" AC inverter system that is reasonably fool proof (in terms of complying with NEC and NRTL LISTINGs) that could be sold in Walmart or Costco. Way too many variables and way to much to expect a "typical" homeowner to understand and verify before the install is made (unless they make a 3 amp @ 120 VAC limit for one P&P system per home--or something similar--and it would still not be "safe" per NEC/LISTING requirements).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 32,226 admin
    GT inverter normally output close to 1.00 PF... There are some controller that can be programmed to -/+ 0.80 PF -- Which can "help" a inductive (or capacitive) load/branch circuit/installation... But that is really a different issue in terms of Utility Support of (typical) inductive loads (induction motors primarily).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    igor1960 wrote: »
    What if I tell you, that I hold two Phds in Electrical Engineering and Electronics. Would this surprise you? You obviously argue this too...

    maybe not believing you by some of your comments, but this isn't electronics here as we are dealing with electricity as per electric power and what the nec and other agencies say. ftr i have 2yrs associate electronics.

    if you feel you are right then call up your local inspector and get him to ok what you're doing. your argument is wasted on us until you can tell us he passed it and why along with an itemized description of what he passed.
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    BB. wrote: »
    At this point, I still do not see any way of making a "plug&play" AC inverter system that is reasonably fool proof (in terms of complying with NEC and NRTL LISTINGs) that could be sold in Walmart or Costco. Way too many variables and way to much to expect a "typical" homeowner to understand and verify before the install is made (unless they make a 3 amp @ 120 VAC limit for one P&P system per home--or something similar--and it would still not be "safe" per NEC/LISTING requirements).

    Looks like you are the only friendly guy among "professors" and I do agree with you, that there must be special measures to dissallow "stupid" installation. However, this doesn't mean that P&P inverters are impossible to use safely and the whole idea should die.
    Check for example my message #50 -- this could be easily implemented and in the near future it wouldn't surprise me that such inverters would be legally available for installation and even UL Listed.
    Imagine, that such inverters (using current plug) could be easily connected to dedicated circuit that has special CB. What's wrong with it? Would this be relatively easy. Obviously comfortable... Inverters currently implement islanding -- ok, that would be another algorithm to implement -- not a big deal...
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    niel wrote: »
    maybe not believing you by some of your comments, but this isn't electronics here as we are dealing with electricity as per electric power and what the nec and other agencies say. ftr i have 2yrs associate electronics.

    if you feel you are right then call up your local inspector and get him to ok what you're doing. your argument is wasted on us until you can tell us he passed it and why along with an itemized description of what he passed.

    The problem is: my local inspector doesn't even have "2yrs associate electronics" degree + it cost $600 to start...
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