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

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  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    vtmaps wrote: »
    Well then, you still have a problem: Start inverter. Add loads to circuit, start another inverter, add more loads, start another inverter, add more loads, call fire department.

    --vtMaps

    OK, just thinking load:
    Pseudocode:
    {
    Production = 0; // sum of all Inverter currents
    Load = 0; // sum of all load currents
    CB = 15; // we have 15AMP circuit breaker;
    DO 1, N
    {
    // -- Start N inverter: overall circuits Production current:
    Production=Production+ProductionN;
    // -- Add LoadN to circuit: overall circuits Load current:
    Load=Load + LoadN:
    // -- Net:
    Net=Production-Load;
    // check
    if(Net < 0) { Production=0; (all inverters stop); Net = Load; }
    if(ABS(Net) > CB) { CB Trip; circuit stops; break }
    }
    FOREVER(Time)
    {
    Net=Production(Time)-Load(Time);
    if(Net < 0) { Production=0; (all inverters stop); Net = Load; }
    if(ABS(Net) > CB) { CB Trip; circuit stops; break }
    }
    }

    So, our circuit stops completely on possible conditions (CB trip):
    1. ABS(Net) > CB current;
    3. Net < 0: the circuit becomes LOAD, ALL inverters will stop; at that moment Production becomes 0 and then if Load > CB current => CB trip

    Most important:
    4. Max. current at any possible point inside the circuit is not more then Net (??? Check remark below) ;
    5. As we were adding sequentially Production1/Load1/Production2/Load3...ProductionN/LoadN - none of each at the moment of addition is more then rated CB current.

    Remark:
    Agree, however that installed at 0/min level currents (at night for example, when both ProductionN and LoadN are at 0), and if then extremely synchronized max. Circuit current is unpredictable...
    That's something to think about -- maybe it's unresolvable...
  • vtmapsvtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    igor1960 wrote: »
    So, our circuit stops production at first Load>Production and either sum Production > CB current or Load > CB current.

    It is possible to have a combination of production and loads that will not shut down the inverters and will not trip the CB, and will still result in exceeding the ampacity of your "dedicated" circuit wiring: Turn on a 14 amp inverter, turn on a 13 amp load, turn on a 13 amp inverter, turn on a 13 amp load, turn on a 13 amp inverter, turn on a 13 amp load, call the fire department.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • solar_davesolar_dave Solar Expert Posts: 2,384 ✭✭✭✭
    Not to go full circle, but if it is a dedicated line whey not just hard wire the dedicated line. Much more acceptable to the code people. Remove the plugs and you remove much of the problematic conditions.
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    solar_dave wrote: »
    Not to go full circle, but if it is a dedicated line whey not just hard wire the dedicated line. Much more acceptable to the code people. Remove the plugs and you remove much of the problematic conditions.

    Yep, looks like this this is the only feasible approach. But then, "P&P" part becomes utopia. I'm about to give up on possible implementation on the site of P&P inverter.

    The only possible, solution that I could see: with P&P inverter having production: is checking Voltage in L1 compare with Voltage in Neutral -- if P&P inverters and/or other producing devices are on the circuit and no LOAD is installed -- then Votage in Neutral would be opposite in phase to voltage in L1 (180degrees rotated, when L1 is positive - N is negative and when L1 is negative N is positive). Voltage in N- couldn't be 0 or in phase with L1, as we have production only on the circuit, and therefore 0 or above at neutral will indicate then there is a LOAD in the circuit equal to or above Production. But even if this is implemented: still no warranty that some of the receptacles with LOAD has positive voltage in neutral and that might cause unpredicatble circular current between LOAD and Production without CB involved. So, the only way, is to move protection in such circuits into all receptacles (special receptacles that dissalow LOAD, by allowing current only from Neutral to L1), but then again "P&P" part becomes utopia.
  • solar_davesolar_dave Solar Expert Posts: 2,384 ✭✭✭✭
    And Hardwired UL approved inverters do exist today! ;)
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Well some of us are not surprised at the results.

    Just imagine how much time would have been saved if only people would listen to begin with.
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    solar_dave wrote: »
    And Hardwired UL approved inverters do exist today! ;)

    Right, but my humble research was devoted to understanding, mostly for myself technical feasibility of those announcements:
    http://energy.gov/articles/energy-de...ems-homeowners
    http://energy.gov/articles/going-sol...ug-and-play-pv

    Bogus then?!
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    Well some of us are not surprised at the results.

    Just imagine how much time would have been saved if only people would listen to begin with.

    Don't recall exactly when, but Einstein used to tell me that: Negative result is the result too. LOL
  • BB.BB. Super Moderators, Administrators Posts: 32,205 admin
    igor1960 wrote: »
    Right, but my humble research was devoted to understanding, mostly for myself technical feasibility of those announcements:
    http://energy.gov/articles/energy-de...ems-homeowners
    http://energy.gov/articles/going-sol...ug-and-play-pv

    Bogus then?!

    Both are:
    Through the Plug and Play Photovoltaics Funding Opportunity Announcement (FOA), the Department of Energy will invest up to $25 million over five years to advance the development of a commercial plug-and-play photovoltaic system, which is envisioned as an off-the-shelf product that is fully inclusive with little need for individual customization. Homeowners can install the system without special training or tools. The homeowner simply plugs the system into a PV-ready circuit and an automatic PV discovery process initiates communication between the system and the utility.

    So--Dedicated PV ready circuit... All this is doing it the "notification" to the utility (and by extension, the local government entities). Interesting--But not "plug and play" as the average homeowner would understand to an existing arbitrary branch circuit--And still nothing about the consumer climbing on a second story roof and installing+wiring up solar panels. Could also integrate charging and grid tie operation for electric vehicles (car charges at night, and if plugged in, can support the utility on hot summer afternoons--another set of questions about cycling costs of batteries, billing, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • igor1960igor1960 Solar Expert Posts: 85 ✭✭✭✭
    BB. wrote: »
    Interesting--But not "plug and play" as the average homeowner would understand to an existing arbitrary branch circuit--And still nothing about the consumer climbing on a second story roof and installing+wiring up solar panels. Could also integrate charging and grid tie operation for electric vehicles (car charges at night, and if plugged in, can support the utility on hot summer afternoons--another set of questions about cycling costs of batteries, billing, etc.).

    Bill, so exactly my point: what would stop consumer into pluging this P&P inverter into any existing outlet? So, there must be protection inside this "P&P inverter" against such case. We didn't find any. So, Energy Department idea is bogus then?
    I'm contemplating giving up on possiblity of such protection. However, the only way I do see is: on the site of P&P inverter, when P&P inverters current crosses 0 (meaning no Production output from inverter), check voltage level in Neutral and L1 => they should be 0 or in the opposite phases. The reason behind this is that any P&P inverter would have PF not equal 1, therefore inverters current is shifted a little bit relative to voltage in L1/Neutral, Right? Then if we do check this voltage at production current equal 0 and there is LOAD somewhere on the circuit (load current would be shifted in phase to production current), then we should see that Neutral/L1 voltage are in phase with each other.
    But the problem is: LOAD could also possibly have reactive current, shifted the same way as PRODUCTION current relative to voltage. Also, there might be more then one P&P inverters on the circuit, and as each would have it's own PF, cross of 0 current on each would not be synchronized with each other, so looking from inside of one inverter, we have no clue that there is remaining equal LOAD and other Production exactly equal in phase, but opposite in direction.
  • BB.BB. Super Moderators, Administrators Posts: 32,205 admin
    Again: "The homeowner simply plugs the system into a PV-ready circuit and an automatic PV discovery process initiates communication between the system and the utility."

    As simple as a new "non-standard" plug on a dedicated PV Circuit (with a registered interface box that wifi's to Internet or ZigBee utility communications shared with your "smart meter", or power line communications with routers on the power poles--who knows)... But when you get the DOE and government involved, there is no "simple" plug--It will be a "smart plug":

    The SAE J1772 charging plug is as inelegant as its name. And the five ports that connect to your car might seem complicated, but they're actually pretty straightforward.

    Attachment not found.

    1 AC power, just like the power plug for your TV.
    2 Proximity detection. This is simply a mechanical switch that makes sure you're plugged in all the way.
    3 Ground wire.
    4 Communications, used to relay data between the car and the charger about how much current is needed.

    How did humanity survive the 2 and 3 prong plugs...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bill von novakbill von novak Solar Expert Posts: 891 ✭✭✭✭
    igor1960 wrote: »
    Bill, so exactly my point: what would stop consumer into pluging this P&P inverter into any existing outlet?

    Special outlet.
    So, there must be protection inside this "P&P inverter" against such case. We didn't find any.

    It's outside the inverter.
  • Hey12Hey12 Registered Users Posts: 15
    Bringing back this old post after reading the whole thread. (Texas, AEP power provider)

    So what you mean is that you can't simply plug this into a dedicated 110v or 220v (depending on setup) and start slowing down the meter to create savings?  This shows you can actually add a plug in a get started with the energy savings.  Check out the link....your thoughts?

    https://mwands.com/250-watt-micro-grid-tie-inverter
  • BB.BB. Super Moderators, Administrators Posts: 32,205 admin
    Physically, yes you can plug a GT inverter into an outlet and all things being equal (i.e., correct solar panel, correct line voltage of 120 OR 240 VAC or other line voltage), it will generate power and add it to your home's electrical wiring.

    Sort of like connecting a bicycle to the back of a car... You can put one (or more) cyclists on their bikes and help push the car forwards.

    The devil is in the details.

    The original post/question was about "plug and play" operation. This gets into safety issues.

    Say you have an electric dryer that draws 20 amps @ 240 VAC single phase (4,800 Watts). And you install 20 amps (@ 240 VAC) worth of GT inverters and solar panels and plug it into the dryer circuit (plug and play).

    Assuming nothing goes wrong, it would actually work quite well (dryer draws power as needed, GT inverters "inject" power into the home's electrical wiring, the energy either is consumed by the dryer and other electrical items, and slow down the electric meter--And if there is more GT power than home loads, it will send power "backwards" through the main breaker panel and electric meter and help power the nearby homes).

    Having the solar panels properly rack mounted (roof or ground mount), bolted to withstand wind (snow loads, hurricane, etc. as require by code), and grounded to a local ground rod (if lighting in area) and grounded to home's safety ground. There are new code requirements for some areas about emergency solar shutdown, walkway access on roof for fire fighters, etc....

    Now, why this may not be safe and/or legal, and/or may not save money.
    • For example, the 20 amp dryer wiring now has 20 Amps from the main breaker, and 20 amps from GT solar. If the dryer has a short circuit, or somebody installed a second dryer outlet for a welder/AC/etc., there are now 40 amps @ 240 VAC available on the "20 amp dryer circuit". A second large load will can overheat the wiring, a short circuit can see 40+ amps without blowing a breaker, etc. "CODE" always assumes there is one power source (AC main wiring, transfer switch for genset, dedicated 20 amp circuit from main panel to GT inverters--NOT plug and play, etc.). So, the standard answer is the add a new 20 Amp @ 240 VAC branch circuit to the main breaker panel and wire it directly to the solar GT inverters.
    • Next--Save money... Maybe. In the "olden days", utility meters were by-directional. The run "forward" charging you for using the utilty power. And "naturally", the would run backwards if the home was feeding energy back to the utility. 30 Years ago, nobody did that, and nobody cared (except in the following case).
    • Some folks would unplug their meter and install it upside down in the socket for about 2 weeks a month. Then put it back upright for the rest of the month (and when the meter was being read by a live meter reader. So, the utilities required new meters to do one of several things (with modern computer controlled utility meters, it is just "software" these days). 
    • One was to prevent the meter from running backwards (sometimes under a function called revenue guard or similar).
    • Another was to set an alarm if the meter was removed or lost power and send back to the utility (remote meter reading)
    • Or make the meter always run forward (meter upside down or not, GT solar or not), meter always ran forward. So a large GT inverter system that feeds more energy than the home uses (typical during summer/sunny weather system designs to make up for winter poor solar conditions), the meter would be charging you for feeding energy back into the grid.
    • Make the meter alarm if it ever measures power flowing backwards to the utility lines (send alarm)
    • Meter analyzes the electrical characteristics of the home (loads, any possible GT inverter or other energy source) and send an alarm if the software "thinks" there is a violation.
    • And a home with lots of solar panels--In California, it is technically illegal for homes to have solar panels unless the have a GT inverter agreement with the customer (California PUC "gives a monopoly to the Utility for ALL power generation--Technically it is illegal for a homeowner or business to ever generate power for their own use). GT Solar and "approved" Co-generation projects are a specific exception.
    In theory, an unapproved GT Solar installation can result in the utility pulling your meter and the local building department "red tagging" a home.

    How likely is this to happen (the meter revenue stuff is pretty standard these day) and the utility pulls a meter or the city red tags a home... I cannot say.

    Solar power, just like any electrical project can be done safely or dangerously--Code and building inspectors (and sometimes homeowner/business insurance inspectors) are there to enforce code. And utilities are their to make money (GT Inverter systems are really subsides from one class of consumers to another class of consumers under the "Green Power" label. Today, the politics are chancing and GT solar has been dramatically curtailed in some localities for various reasons).

    And just an example of what can happen with "gray market" solar panels (the system itself was permitted and inspected--But they missed the non-UL panels):

    https://forum.solar-electric.com/discussion/3375/panel-fire-question/p1

    And there have been many fires at Walmarts and other large facilities because of faulty workmanship and other issues:

    https://duckduckgo.com/?q=walmart+solar+panel+fire&atb=v122-1__&ia=web

    I am not going to "enforce" my way or the highway on the forum here regarding discussions like this... We can discuss the issues, answer questions, and warn people of issues with doing guerrilla installations and the hazards, etc... But we are all adults here.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Hey12Hey12 Registered Users Posts: 15
    Thank you for your reply.  Keep in mind that the panels would be on a dedicated 220 outlet as you stated above.  Nothing else would be tied in ever.  The goal wouldn't be the have the smart meter go backward, just to slow it down where I could save 30.00 to 60.00 dollars a month and being careful not to tip off my energy provider AEP, at least for now.  I'll post an interesting conversation I had with an electrician in a few. 
  • littleharbor2littleharbor2 Solar Expert Posts: 1,639 ✭✭✭✭
    Saving 30 to 60 dollars a month will take quite a bit more than a couple solar panels and GTI's

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 540 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • Hey12Hey12 Registered Users Posts: 15
    Saving 30 to 60 dollars a month will take quite a bit more than a couple solar panels and GTI's
    Indeed.  
  • Hey12Hey12 Registered Users Posts: 15
    Here's the conversation with the electrician that installs:

    Me: So what you mean is that you can't simply plug this into a dedicated 110v or 220v (depending on setup) and start slowing down the meter to create savings?

    Electrician: well I mean it could lower your bill, but you won't get credit for it or money back or a credit from the utility co, you have to have the meter changed out on your house, get your system approved, etc. For instance, if I put up 2/150watt solar panels to the micro-inverter, it would put out enough to probably alter the cost of my swamp cooler, which on low speed, uses 232 watts of power, it would generate some electricity to save on the rest of my house as long as there are things turned on, but if the meter goes backward at all if it does, it may not, the utility co will see it and then you're in trouble. The old analog meters, no, but the reason the utility co installed all these new meters was to spy on people and make sure they aren't using solar power without their permission.

    Me:  Thank you for answering the question. The video is a little old and I wasn't sure if anyone would reply. OK, I understand where you coming from. So basically, with my setup going into a dedicated 220 outlet it would work in lowering my bill but I have to be careful in making sure it doesn't go backwards because that's where the problem starts. As long as I stay below range with my setup, I should be ok, right? Also, my micro-inverters will shut off in the event that the electric grid goes down along with a backup breaker going down. This is to ensure if a worker is working on the lines, they wouldn't get shocked.

    Electrician:  make sure your inverter will put out 220 volts if you use 220, the same thing for 110. if you have the new style meters, then yes the utility co can see if it goes backward, then they will stop at your house and ask why. I have had to replace service panels on houses that were hard-wired and they got caught and turned power off. do not plug a 110 into a 220 outlet. as long as you put out a little less than you use it should be alright. I was looking into this just to try and knock my bill down a little. like 30 to 50 dollars a month.

    Me:  Yes, the savings of what I am looking at are the same, around 30.00-60.00 a month. Remember there will be no inverter since the microinverters have them built-in. With this, I won't lose any power as opposed to connecting a separate inverter that converts dc to ac. This would also be on a dedicated 220 line. The object is to make sure the smart meter slows down but not go backward. With this set-up, I feel it would be ok, let's say you? I can always place the savings to the side until I saved enough to get proper permits and such....
    Have you looked into the new Legion solar company? The concept is about the same only I don't have a monitor that would slow panel production for me.

    Electrician:  the inverter is built into the microinverter so you will lose a little, as like I said 2/150 watt panels might produce 200 usable watts at the plug end in your house.anytime you convert dc to ac you use power and you lose a little. no, I have not heard of legion solar, I will look, I have installed some power modulus in my systems that shift power from high wattage to other parts of the house during peak times to lower the electric bill. If you watch the video, above, when he plugs in the panel, look at the kilowatt meter, it reads 90 watts, so out of his 230-watt panel, he is getting 90 watts, so if this was my scenario using my 232 watts for swamp cooler, this setup would cut my power usage for the swamp cooler alone, in half. and not make my meter go backward,
  • BB.BB. Super Moderators, Administrators Posts: 32,205 admin
    Let's do some quick math... Say 300 Watts of GT Solar.
    Corpus Christi Texas, fixed array facing south at ~30 degree from horizontal:
    https://pvwatts.nrel.gov/pvwatts.php
    MonthSolar Radiation
    ( kWh / m2 / day )


    January4.36

    February4.97

    March5.41

    April5.80

    May6.00

    June6.15

    July6.31

    August6.51

    September5.98

    October5.89

    November4.92

    December4.34

    Annual5.55


    The standard equation would be:
    • 300 Watt array * 0.77 GT solar eff * 5.55 hours per day (1 year average) * 365 days per year = 467,948 WH = 467 kWH per year
    • 300 Watt array * 0.77 GT solar eff = 231 Watts peak (few cool/clear days a year around noon)
    • 467 WH per year * $0.11 / kWH = $51.37 per year
    Assuming my guess for your location is correct, the above is the long term year to year average harvest.

    If you are in Texas, you generally have low electrical costs... In California, we can be in the $0.20 to $0.40 per kWH range (time of use, location, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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